Hyperactivity and impaired response habituation in hyperdopaminergic mice

Abnormal dopaminergic transmission is implicated in schizophrenia, attention deficit hyperactivity disorder, and drug addiction. In an attempt to model aspects of these disorders, we have generated hyperdopaminergic mutant mice by reducing expression of the dopamine transporter (DAT) to 10% of wild-type levels (DAT knockdown). Fast-scan cyclic voltammetry and in vivo microdialysis revealed that released dopamine was cleared at a slow rate in knockdown mice, which resulted in a higher extracellular dopamine concentration. Unlike the DAT knockout mice, the DAT knockdown mice do not display a growth retardation phenotype. They have normal home cage activity but display hyperactivity and impaired response habituation in novel environments. In addition, we show that both the indirect dopamine receptor agonist amphetamine and the direct agonists apomorphine and quinpirole inhibit locomotor activity in the DAT knockdown mice, leading to the hypothesis that a shift in the balance between dopamine auto and heteroreceptor function may contribute to the therapeutic effect of psychostimulants in attention deficit hyperactivity disorder.     

Validation of Serum Amyloid α as an Independent Biomarker for Progression-Free and Overall Survival in Metastatic Renal Cell Cancer Patients

Background

We recently identified apolipoprotein A2 (ApoA2) and serum amyloid α (SAA) as independent prognosticators in metastatic renal cell carcinoma (mRCC) patients, thereby improving the accuracy of the Memorial-Sloan Kettering Cancer Center (MSKCC) model.

Objective

Validate these results prospectively in a separate cohort of mRCC patients treated with tyrosine kinase inhibitors (TKIs).

Design, setting, and participants

For training we used 114 interferon-treated mRCC patients (inclusion 2001–2006). For validation we studied 151 TKI-treated mRCC patients (inclusion 2003–2009).

Measurements

Using Cox proportional hazards regression analysis, SAA and ApoA2 were associated with progression-free survival (PFS) and overall survival (OS). In 72 TKI-treated patients, SAA levels were analyzed longitudinally as a potential early marker for treatment effect.

Results and limitations

Baseline ApoA2 and SAA levels significantly predicted PFS and OS in the training and validation cohorts. Multivariate analysis identified SAA in both separate patient sets as a robust and independent prognosticator for PFS and OS. In contrast to our previous findings, ApoA2 interacted with SAA in the validation cohort and did not contribute to a better predictive accuracy than SAA alone and was therefore excluded from further analysis. According to the tertiles of SAA levels, patients were categorized in three risk groups, demonstrating accurate risk prognostication. SAA as a single biomarker showed equal prognostic accuracy when compared with the multifactorial MSKCC risk mode. Using receiver operating characteristic analysis, SAA levels >71 ng/ml were designated as the optimal cut-off value in the training cohort, which was confirmed for its significant sensitivity and specificity in the validation cohort. Applying SAA >71 ng/ml as an additional risk factor significantly improved the predictive accuracy of the MSKCC model in both independent cohorts. Changes in SAA levels after 6–8 wk of TKI treatment had no value in predicting treatment outcome.

Conclusions

SAA but not ApoA2 was shown to be a robust and independent prognosticator for PFS and OS in mRCC patients. When incorporated in the MSKCC model, SAA showed additional prognostic value for patient management.     

Correlation between urinary levels of histamine metabolites in 24-hour urine and morning urine samples of man: influence of histamine-rich food

In this study, we have determined and correlated the excretion of the 2 most important histamine metabolites, N tau-methylhistamine and N tau-methylimidazoleacetic acid, in 24-hour urine and morning urine samples of 14 normal healthy persons. We found no significant difference between morning urine and 24-hour urine samples, provided that the subjects were on a histamine-poor diet for at least 24 hours. We also studied the influence of the consumption of histamine-rich foodstuffs on the reliability of these parameters. The morning urinary N tau-methylhistamine excretion is less affected by histamine-rich food-stuffs and therefore proposed to be the most reliable parameter for endogeneous histamine release.     

Quantitative analysis of EEG power spectra in experimental hepatic encephalopathy

During galactosamine-induced acute liver failure in white male Wistar rats, EEG was recorded at regular intervals. Spectral analysis was done as described by Kropveld and co-workers in 1983. The specificity of the anomalies in the power-density spectra is tested by comparing the changing patterns with those caused by several pharmaceutical agents--ether, diazepam, pentobarbital. Quantification of the observed anomalies is discussed.     

Respiratory syncytial virus infection augments NOD2 signaling in an IFN‐β‐dependent manner in human primary cells

Respiratory syncytial virus (RSV) is a major cause of lower respiratory tract infections in infants, with remarkable variability in disease severity. An exaggerated proinflammatory response and influx of leukocytes is part of the pathogenesis of severe RSV disease. Here, we show an increase in proinflammatory cytokine production by human immune cells after stimulation with RSV and muramyl dipeptide (MDP), which is recognized by nucleotide‐binding oligomerization domain containing 2 (NOD2). PBMCs from Crohn's disease patients homozygous for the 3020insC mutation in the NOD2 gene did not show a synergistic response to stimulation with RSV and MDP, suggesting that NOD2 is essential for the observed synergy. Further experiments aimed at identifying the viral ligand indicated that viral RNA plays an essential role in the recognition of RSV. Stimulation with RSV or Poly(I:C) induced IFN‐β expression, which resulted in an increased expression of the viral receptors TLR3 and RIG‐I, as well as an increased NOD2 expression. Our data indicate that IFN‐β induction by viral RNA is an essential first step in the increased proinflammatory response to MDP. We hypothesize that the enhanced proinflammatory response to MDP following RSV infection may be an important factor in determining the outcome of the severity of disease.     

High frequency of copy-neutral LOH in MUTYH-associated polyposis carcinomas

Genetic instability is known to drive colorectal carcinogenesis. Generally, a distinction is made between two types of genetic instability: chromosomal instability (CIN) and microsatellite instability (MIN or MSI). Most CIN tumours are aneuploid, whereas MSI tumours are considered near-diploid. However, for MUTYH-associated polyposis (MAP) the genetic instability involved in the carcinogenesis remains unclear, as near-diploid adenomas, aneuploid adenomas and near-diploid carcinomas have been reported. Remarkably, our analysis of 26 MAP carcinomas, using SNP arrays and flow sorting, showed that these tumours are often near-diploid (52%) and mainly contain chromosomal regions of copy-neutral loss of heterozygosity (LOH) (71%). This is in contrast to sporadic colon cancer, where physical loss is the main characteristic. The percentage of chromosomal gains (24%) is comparable to sporadic colorectal cancers with CIN. Furthermore, we verified our scoring of copy-neutral LOH versus physical loss in MAP carcinomas by two methods: fluorescence in situ hybridization, and LOH analysis using polymorphic markers on carcinoma fractions purified by flow sorting. The results presented in this study suggest that copy-neutral LOH is an important mechanism in the tumorigenesis of MAP.     

Celecoxib delays cognitive decline in an animal model of neurodegeneration

Cyclooxygenase-2 (COX-2) is thought to play a role in the pathogenesis of various neurodegenerative disorders. However, clinical trials with COX-2 inhibitors have yielded contradictory results. In the present study we investigated whether COX-2 plays a role in the behavioral and cognitive impairments seen in olfactory bulbectomized rats. These impairments arise from neurodegenerative processes. First, we determined the time course of the OBX-induced behavioral (hyperactivity) and cognitive changes (fear memory) and how these correlate with changes in COX-2 mRNA expression in hippocampus. This experiment showed that the major impairments in behavior and cognition developed between Days 3 and 14 after OBX surgery, which correlated with changes in mRNA levels of COX-2, which increased at Days 7 and 14 after surgery but not anymore at day 28. In a subsequent experiment, rats were treated, starting two days before surgery, with the COX-2 inhibitor celecoxib (10mg/kg, dissolved in drinking water) for 4 weeks. OBX-induced hyperactivity in the open field was normalized after 2 weeks of celecoxib treatment, but not longer after 4 weeks. Celecoxib partly rescued fear learning and memory deficits without affecting spatial memory. The effects of celecoxib on fear memory lasted up to 1 week posttreatment, but disappeared thereafter. Our results show that COX-2 plays a limited role (both in magnitude and time) in the development of the OBX syndrome.     

Correlation between urinary levels of histamine metabolites in 24-hour urine and morning urine samples of man: Influence of histamine-rich food

In this study, we have determined and correlated the excretion of the 2 most important histamine metabolites, N-methylhistamine and N-methylimidazoleacetic acid, in 24-hour urine and morning urine samples of 14 normal healthy persons. We found no significant difference between morning urine and 24-hour urine samples, provided that the subjects were on a histamine-poor diet for at least 24 hours. We also studied the influence of the consumption of histamine-rich foodstuffs on the reliability of these parameters. The morning urinary N-methylhistamine excretion is less affected by histamine-rich foodstuffs and therefore proposed to be the most reliable parameter for endogeneous histamine release.