Prostaglandin D synthase (beta-trace) in healthy human sleep

STUDY OBJECTIVES: The prostaglandin D system plays an important role in animal sleep. In humans, alterations in the prostaglandin D system have been found in diseases exhibiting sleep disturbances as a prominent symptom, such as trypanosoma infection, systemic mastocytosis, bacterial meningitis, major depression, or obstructive sleep apnea. Assessment of this system's activity in relation to human physiologic sleep was the target of the present study. DESIGN: Serum concentrations of lipocalin-type prostaglandin D synthase (L-PGDS, former beta-trace), and plasma levels of the pineal hormone melatonin were measured in 20 healthy humans (10 women, 10 men; aged: 23.3 +/- 2.39 years) at 4-hour intervals over a period of 5 days and nights, which included physiologic sleep, rapid eye movement sleep deprivation, and total sleep deprivation. In addition, the serum L-PGDS and plasma melatonin levels of 6 subjects were determined under conditions of bright white (10,000 lux) or dark red light (< 50 lux) in a crossover design during total sleep deprivation. Nocturnal blood sampling was performed by a through-the-wall tube system. L-PGDS was measured by an automated immunonephelometric assay, and melatonin was analyzed by direct radioimmunoassay. RESULTS: Serum L-PGDS concentrations showed marked time-dependent changes with evening increases and the highest values at night (P < .0005). This nocturnal increase was suppressed during total sleep deprivation (P < .05), independent of external light conditions and melatonin secretion. Rapid eye movement sleep deprivation had no impact on circulating L-PGDS levels. CONCLUSIONS: The circadian L-PGDS pattern and its suppression by total sleep deprivation indicate an interaction of the prostaglandin D system and human sleep regulation. L-PGDS measurements may well provide new insights into physiologic and pathologic sleep regulation in humans.     

Identification and characterization of survivin‐derived H‐2Kb‐restricted CTL epitopes

Survivin is overexpressed in several malignancies and in tumor‐associated endothelium making it an attractive target for therapeutic cytotoxic T‐cell responses. Thus, it would be important to test this notion in preclinical models. Consequently, we screened the murine survivin sequence for potential binding K^b‐restricted octamer peptide epitopes. Two epitopes, which bind strongly to K^b, were selected to test their immunogenicity in vivo. Spleen cells from mice vaccinated by intradermal injection of mature DC pulsed with these peptides displayed reactivity to the respective epitopes. The natural processing and presentation of these epitopes by tumor cells was evident by the killing of murine melanoma cells by vaccination‐induced T cells. Subcutaneous challenge with syngeneic melanoma demonstrated the protective immunity of this vaccination. Notably, analysis of the vessel density in subcutaneous tumors revealed that survivin‐specific vaccination significantly reduced the number of intratumoral vessels. In summary, we demonstrated the immunogenicity of two K^b‐restricted peptide epitopes derived from the murine survivin protein; moreover, survivin‐specific vaccination not only resulted in a reduction of tumor cells but also the tumor supplying blood vessels. The presented preclinical model for survivin‐directed vaccination may serve as a valuable tool to improve already running clinical trials in a syngeneic tumor model.     

Torque response to external perturbation during unconstrained goal-directed arm movements

It is unclear to what extent control strategies of 2D reaching movements of the upper limbs also apply to movements with the full seven degrees of freedom (DoFs) including rotation of the forearm. An increase in DoFs may result in increased movement complexity and instability. This study investigates the trajectories of unconstrained reaching movements and their stability against perturbations of the upper arm. Reaching movements were measured using an ultrasound marker system, and the method of inverse dynamics was applied to compute the time courses of joint torques. In full DoF reaching movements, the velocity of some joint angles showed multiple peaks, while the bell-shaped profile of the tangential hand velocity was preserved. This result supports previous evidence that tangential hand velocity is an essential part of the movement plan. Further, torque responses elicited by external perturbation started shortly after perturbation, almost simultaneously with the perturbation-induced displacement of the arm, and were mainly observed in the same joint angles as the perturbation torques, with similar shapes but opposite signs. These results indicate that these torque responses were compensatory and contributed to system stabilization.     

Deficits of cortical oculomotor mechanisms in cerebellar atrophy patients

Commonly, the cerebellum is not associated with cortical components of saccadic eye movement programming. The present study investigates cerebellar effects on visually guided saccades in reflexive tasks (step, gap, overlap) and on internally driven saccades in intentional tasks (anti, memory, short memory sequences of four targets) in five patients with isolated cerebellar atrophy. The cerebellar dysfunction led to impairments in both reflexive and intentional saccades. Cerebellar atrophy patients showed an increase in the gain variability and an increase in the saccade latency. Furthermore, in the memory and anti task, suppression and pro-saccade errors were more frequent in the atrophy group compared to the control group. In the sequence task, patients had difficulties reproducing all four target locations in the order of the displayed sequence. The high variability of the saccade gain is a common observation in cerebellar atrophy patients and can be explained by the general variability present in the saccadic system. The increase in the saccade latency could be due to a cerebellar contribution to cortical processes related to fixation and target selection preceding the initiation of a saccade. Furthermore, the frequent occurrence of saccade errors in the memory and anti task suggests a cerebellar involvement in frontal inhibition of unwanted reflexive saccades. The impaired reproduction of saccade sequences in atrophy patients points to a deficit in short-term memory processes. Thus, this study provides further evidence that the cerebellum is involved in different cortical mechanisms related to the control of saccadic eye movements.     

Relation between the metrics of the presaccadic attention shift and of the saccade before and after saccadic adaptation

A shift of the visual attention focus is known to precede saccades. However, how the metrics of both this presaccadic attention shift and the saccade are coupled is still unclear. We altered the saccade size by short-term saccadic adaptation to determine whether the attention focus would still be shifted to the location of the saccade target or to the modified postsaccadic eye position. The results showed that saccadic adaptation had no influence on the presaccadic attention shift. Thus either different processes determine the metrics of the attention shift and of the saccade or saccadic adaptation causes only modifications on a lower hierarchical level of saccade programming, thereby not influencing the metrics of the attention shift.     

Differential effect of a distractor on primary saccades and perceptual localization

A distractor presented nearby the target of a goal-directed short latency saccade leads to spatial averaging, that is, the saccade lands between the target and the distractor. This so-called global effect is a characteristic feature of the spatial processing underlying the programming of saccadic eye movements. To determine whether this effect of near distractors on saccade metrics is also reflected in perceptual localization, subjects performed a saccade task and a perceptual localization task using identical, briefly flashed visual stimuli. To make the available visual processing time for saccades and perception more similar, we followed the target with a mask.Without the mask, primary saccades with short latency landed between target and distractor. The distractor had less effect on primary saccades with longer latencies (>200 ms) and did not affect the final eye position after late secondary saccades in the dark. This indicates that the oculomotor system can correctly use information about the target location 200 ms after the target flash even if no visual stimulus is present during this period. Likewise the presence of a distractor did not affect perceptual localization.Under the masking condition a similar global effect occurred for primary saccades with short latencies, but the latency dependence of the global effect was weakened. Secondary saccades and perceptual localization still did not show a global effect. The results suggest that the primary saccade is based on a specific target acquisition process that differs from that used for spatial perception and for the programming of memory-guided corrective saccades.     

Urinary concentration and tissue messenger RNA expression of monocyte chemoattractant protein-1 as an indicator of the degree of hydronephrotic atrophy in partial ureteral obstruction

PURPOSE: To find a potential prognostic marker of the induction of hydronephrotic atrophy in congenital hydronephrosis we investigated whether the messenger (m)RNA expression and urinary concentration of monocyte chemoattractant protein-1 (MCP-1) correlated with the degree of partial ureteral obstruction, and subsequent hydronephrotic atrophy and interstitial fibrosis. MATERIALS AND METHODS: We created left partial ureteral obstruction in 96 juvenile Wistar rats and complete ureteral obstruction in 18, while 16 underwent sham operation. Depending on excretion of contrast medium into the renal pelvis after 3 days we defined 2 degrees of hydronephrosis. Renal mRNA expression of MCP-1, and renal pelvic and bladder urinary concentrations of MCP-1 were measured after 1, 2 and 3 weeks, and compared with the degree of hydronephrotic atrophy. RESULTS: Grade 1 partial ureteral obstruction resulted in mild histological changes. Grade 2 partial and complete obstruction resulted in significant hydronephrotic atrophy. MCP-1 mRNA expression in the kidney remained unchanged in grade 1 partial obstruction but was moderately increased in grade 2 partial obstruction and clearly over expressed in complete ureteral obstruction. The renal pelvic urinary concentration of MCP-1 was not higher in rats with grade 1 partial obstruction than in sham operated animals but it was significantly increased in those with grade 2 partial and complete obstruction. CONCLUSIONS: mRNA expression and the urinary concentration of MCP-1 correlate with the degree of obstruction and subsequent renal damage in hydronephrosis. They may serve as prognostic markers in children with congenital hydronephrosis.     

Resistance to chemotherapy mediated by TrkB in neuroblastomas

Neuroblastoma is a common childhood tumor derived from the peripheral nervous system. Favorable neuroblastomas usually express TrkA, the receptor for nerve growth factor (NGF), whereas unfavorable, MYCN-amplified neuroblastomas usually express TrkB and its ligand, brain-derived neurotrophic factor (BDNF). Here, we provide evidence that the TrkB-BDNF pathway is associated with enhanced survival and resistance to chemotherapy in neuroblastoma. We transfected the neuroblastoma line SH-SY5Y, which has endogenous expression of BDNF, with a full-length TrkB expression vector, and obtained clones with moderate or high levels of expression. Cells were exposed in vitro to chemotherapy agents used to treat neuroblastomas: doxorubicin, etoposide (VP16), and cisplatin. Chemoresistance was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for cell survival and by ELISA for cell death. In all cases, the TrkB-expressing subclones were more resistant to treatment than the parent line. Furthermore, when the TrkB tyrosine kinase was blocked with the Trk-specific inhibitor CEP-2563, or by neutralizing antibody to BDNF, sensitivity to chemotherapy was significantly increased. We also found constitutive phosphorylation of AKT at the Ser-473 site in TrkB transfectants, whereas there was only a minimal level of constitutive phosphorylation of AKT in SY5Y cells. These results show that the TrkB-BDNF pathway provides a survival advantage when exposed to DNA-damaging reagents, and, therefore, this autocrine pathway may play an important role in mediating the drug-resistant phenotype associated with TrkB-expressing neuroblastomas. Activation of PI3K/AKT survival pathway may contribute to the increased drug resistance in TrkB-expressing neuroblastomas.