Chronic stress enhances methamphetamine-induced extracellular glutamate and excitotoxicity in the rat striatum

Striking parallels exist between the neurochemical and toxic effects of stress and methamphetamine. Despite these similarities, no studies have examined how stress may promote the toxic effects of methamphetamine (METH). The current study tested the hypothesis that chronic stress enhances METH toxicity by augmenting glutamate (GLU) release and excitotoxicity in response to METH administration. Adult male Sprague-Dawley rats were exposed to 10 days of unpredictable stress and then received either saline or METH (7.5 mg/kg, i.p., once every 2 h x four injections). Prior exposure to unpredictable stress acutely enhanced the striatal extracellular GLU concentrations in response to METH, and eventually caused proteolysis of the cytoskeleton protein spectrin. Administration of the corticosterone synthesis inhibitor, metyrapone (25 mg/kg, i.p., prior to each stressor), during unpredictable stress attenuated the enhanced striatal GLU release in response to METH, blocked spectrin proteolysis, and attenuated METH-associated toxicity measured by long-term depletions in the dopamine and serotonin tissue content as well as depletions in dopamine and serotonin transporter immunoreactivity of the striatum. In summary, prior exposure to unpredictable stress enhances METH-induced elevations of GLU in the striatum, resulting in long-term excitotoxic damage and an augmentation of damage to dopamine and serotonin terminals. These studies provide a neurochemical basis for how stress contributes to the deleterious effects of METH abuse.     

The mechanical performance and histomorphological structure of the descending aorta in hyperthyroidism

Thyroid hormones decrease systemic vascular resistance by directly affecting vascular smooth muscle relaxation. There is limited literature about their effect on the mechanical performance of the aortic wall. Therefore, the authors determined the influence of hyperthyroidism on the mechanical properties and histomorphological structure of the descending thoracic aorta in rats. Severe hyperthyroidism was induced in 20 male Wistar rats by administering L-thyroxine (T(4)) in their drinking water for 8 weeks; age-matched normal euthyroid rats acted as controls. Animals were sacrificed, and the mechanical and histomorphometrical characteristics of the descending thoracic aorta were studied. The aortic wall of hyperthyroid rats was stiffer than that of euthyroid animals at the upper physiologic levels of stress or strain (p < 0.05) but less stiff at the lower physiologic and lower levels (p < 0.05). The aorta of hyperthyroid animals compared with that of euthyroid ones showed an increase of the internal and external diameters (p < 0.05), the media area (p < 0.05), the number of smooth muscle cell nuclei (p < 0.05), and the collagen density (p < 0.05) and a decrease in the elastin laminae thickness (p < 0.001) and elastin density (p < 0.001). In hyperthyroid rats, the aortic wall was stiffer at the upper physiologic and higher levels of stress and strain. These changes correlated with microstructural changes of the aortic wall. The coexistence of hyperthyroidism with disease states or clinical conditions that predispose to increased arterial pressure may be associated with increased arterial stiffness and have undesirable consequences on the mechanical performance of the thoracic aorta and hemodynamic homeostasis. These changes could lead to an increased risk for developing vascular complications.     

CD28-mediated regulation of multiple myeloma cell proliferation and survival

Although interactions with bone marrow stromal cells are essential for multiple myeloma (MM) cell survival, the specific molecular and cellular elements involved are largely unknown, due in large part to the complexity of the bone marrow microenvironment itself. The T-cell costimulatory receptor CD28 is also expressed on normal and malignant plasma cells, and CD28 expression in MM correlates significantly with poor prognosis and disease progression. In contrast to T cells, activation and function of CD28 in myeloma cells is largely undefined. We have found that direct activation of myeloma cell CD28 by anti-CD28 mAb alone induces activation of PI3K and NFkappaB, suppresses MM cell proliferation, and protects against serum starvation and dexamethasone (dex)-induced cell death. Coculture with dendritic cells (DCs) expressing the CD28 ligands CD80 and CD86 also elicits CD28-mediated effects on MM survival and proliferation, and DCs appear to preferentially localize within myeloma infiltrates in primary patient samples. Our findings suggest a previously undescribed myeloma/DC cell-cell interaction involving CD28 that may play an important role in myeloma cell survival within the bone marrow stroma. These data also point to CD28 as a potential therapeutic target in the treatment of MM.     

Almost all articles on cancer prognostic markers report statistically significant results

We aimed to understand the extent of the pursuit for statistically significant results in the prognostic literature of cancer. We evaluated 340 articles included in prognostic marker meta-analyses (Database 1) and 1575 articles on cancer prognostic markers published in 2005 (Database 2). For each article, we examined whether the abstract reported any statistically significant prognostic effect for any marker and any outcome ('positive' articles). 'Negative' articles were further examined for statements made by the investigators to overcome the absence of prognostic statistical significance. We also examined how the articles of Database 1 had presented the relative risks that were included in the respective meta-analyses. 'Positive' prognostic articles comprised 90.6% and 95.8% in Databases 1 and 2, respectively. Most of the 'negative' prognostic articles claimed significance for other analyses, expanded on non-significant trends or offered apologies that were occasionally remote from the original study aims. Only five articles in Database 1 (1.5%) and 21 in Database 2 (1.3%) were fully 'negative' for all presented results in the abstract and without efforts to expand on non-significant trends or to defend the importance of the marker with other arguments. Of the statistically non-significant relative risks in the meta-analyses, 25% had been presented as statistically significant in the primary papers using different analyses compared with the respective meta-analysis. We conclude that almost all articles on cancer prognostic marker studies highlight some statistically significant results. Under strong reporting bias, statistical significance loses its discriminating ability for the importance of prognostic markers.     

Induction of colon tumorigenesis by glutathione depletion in p53-knock-out mice

In order to examine the role of glutathione (GSH), a key cellular antioxidant, on spontaneous tumor development, we tested the effects of buthionine sulfoximine (BSO), a specific inhibitor of GSH synthesis, and 1,2-oxothiazolidine-4-carboxylic acid (OTCA), a cysteine and GSH precursor, on tumor incidence and spectrum in p53 nullizygous (p53-/-) transgenic mice. Mice were randomly assigned to three groups: control (no treatment), BSO (20 mM in drinking water) or OTCA (6 g/kg in the diet) (n=30 per group). After 10 weeks, GSH levels were decreased 29-88% in all tissues except liver and brain in BSO-treated mice, while no changes were observed in most tissues from OTCA-treated animals. Mice in all groups showed similar survival patterns as well as incidence of the most commonly observed tumors: i.e., lymphomas (80%) and other tumors (38%). However, a 5-fold increase in incidence of colonic tumors (from 4-20%) was observed in the BSO-treated group, suggesting that GSH deficiency and loss of p53 function play contributory roles in colon carcinogenesis.     

Pulsed cyclophosphamide, thalidomide and dexamethasone regimen for previously treated patients with multiple myeloma: long term follow up and disease control after subsequent treatments

There are limited data regarding the long term follow up after thalidomide based regimen and the outcome of patients when they progress and they receive further treatment. We reassessed our original series of 43 patients with previously treated multiple myeloma who had received a pulsed cyclophosphamide, thalidomide, dexamethasone (CTD) regimen. Among the 43 patients, 14 did not respond to pulsed CTD and 29 (67%) achieved at least a partial response. The median PFS for all patients was 10 months. After a median follow up of 24 months (range 1 - 62), the 3 year PFS is 14% and 3 patients remain off treatment and without progression for 55+, 55+ and 56+ months respectively. Moreover, 28% of patients who progressed after CTD achieved a partial response after subsequent treatment which included thalidomide, bortezomib or lenalidomide. The median PFS of these patients was 5 months and the 1 year PFS was 20%. Furthermore, 31% of patients who had responded to CTD and then progressed (CTD sensitive) responded to subsequent treatment. We conclude that some patients enjoy long responses after CTD and that several patients who progress after CTD may respond to treatment with a novel agent-based regimen.     

Multimodal imaging of experimental choroidal neovascularization

AIM: To compare choroidal neovascularization (CNV) lesion measurements obtained by in vivo imaging modalities, with whole mount histological preparations stained with isolectin GS-IB4, using a murine laser-induced CNV model. METHODS: B6N.Cg-Tg(Csf1r-EGFP)1Hume/J heterozygous adult mice were subjected to laser-induced CNV and were monitored by fluorescein angiography (FA), multicolor (MC) fundus imaging and optical coherence tomography angiography (OCTA) at day 14 after CNV induction. Choroidal-retinal pigment epithelium (RPE) whole mounts were prepared at the end of the experiment and were stained with isolectin GS-IB4. CNV areas were measured in all different imaging modalities at day 14 after CNV from three independent raters and were compared to choroidal-RPE whole mounts. Intraclass correlation coefficient (ICC) type 2 (2-way random model) and its 95% confidence intervals (CI) were calculated to measure the correlation between different raters'' measurements. Spearman''s rank correlation coefficient (Spearman''s r) was calculated for the comparison between FA, MC and OCTA data and histology data. RESULTS: FA (early and late) and MC correlates well with the CNV measurements ex vivo with FA having slightly better correlation than MC (FA early Spearman''s r=0.7642, FA late Spearman''s r=0.7097, and MC Spearman''s r=0.7418), while the interobserver reliability was good for both techniques (FA early ICC=0.976, FA late ICC=0.964, and MC ICC=0.846). In contrast, OCTA showed a poor correlation with ex vivo measurements (Spearman''s r=0.05716) and high variability between different raters (ICC=0.603). CONCLUSION: This study suggests that FA and MC imaging could be used for the evaluation of CNV areas in vivo while caution must be taken and comparison studies should be performed when OCTA is employed as a CNV monitoring tool in small rodents.     

Vasopressin and epinephrine in the treatment of cardiac arrest: an experimental study

Background

Epinephrine remains the drug of choice for cardiopulmonary resuscitation. The aim of the present study is to assess whether the combination of vasopressin and epinephrine, given their different mechanisms of action, provides better results than epinephrine alone in cardiopulmonary resuscitation.

Methods

Ventricular fibrillation was induced in 22 Landrace/Large-White piglets, which were left untreated for 8 minutes before attempted resuscitation with precordial compression, mechanical ventilation and electrical defibrillation. Animals were randomized into 2 groups during cardiopulmonary resuscitation: 11 animals who received saline as placebo (20 ml dilution, bolus) + epinephrine (0.02 mg/kg) (Epi group); and 11 animals who received vasopressin (0.4 IU/kg/20 ml dilution, bolus) + epinephrine (0.02 mg/kg) (Vaso-Epi group). Electrical defibrillation was attempted after 10 minutes of ventricular fibrillation.

Results

Ten of 11 animals in the Vaso-Epi group restored spontaneous circulation in comparison to only 4 of 11 in the Epi group (p = 0.02). Aortic diastolic pressure, as well as, coronary perfusion pressure were significantly increased (p < 0.05) during cardiopulmonary resuscitation in the Vaso-Epi group.

Conclusion

The administration of vasopressin in combination with epinephrine during cardiopulmonary resuscitation results in a drastic improvement in the hemodynamic parameters necessary for the return of spontaneous circulation.     

Antagonists of retinoic acid and BMP4 affect fetal mouse osteogenesis and odontoblast differentiation

Retinoic acid and bone morphogenetic protein (BMP4) are endogenous factors indispensable for the physiological development of vertebrates. The proximate aim of the present study was to investigate whether the natural compound citral (a retinoic acid synthesis inhibitor) and a monoclonal, anti-BMP4 antibody, administered to pregnant mice affect in the fetuses cranial osteogenesis and odontoblast differentiation. The present investigation was motivated by the fact that, retinoic acid inhibitors and BMP4 neutralizers may frequently contact human tissues (both intentional and unintentional, and/or unconsciously) inducing unanticipated effects. Our ultimate goal is the prevention of side effects and, future clinical implementation of the results. To this end, pregnant, white mice (balb-c Mus musculus) were intra-abdominally injected with either citral or anti-BMP4 antibody at the 9th gestational day. Newborns were processed within 5 h, postnatal. Results were evaluated (a) macroscopically, (b) stereoscopically, following histochemical double staining of cartilage and osseous tissues and, (c) microscopically after (c₁) histological staining of paraffin sections, and, (c₂) immunohistochemical detection of apoptosis. Data indicate that in vivo administration of citral (biomimicking hypovitaminosis A) caused restriction/retardation of cranial chondrogenesis and osteogenesis. Apoptosis was not detected in teeth tissues. In vivo administration of anti-BMP4 antibody resulted in a transitory interference with the normal course of odontoblast differentiation and the production of pre-dentin, whereas, delay in the ossification also included the alveoli. Animals inspected in adulthood displayed a fairly normal phenotype. It is concluded that those two substances, under their concentrations experienced, are quite safe for the public.