On the pharmacological phenocopying of memory mutations inDrosophila: Alkylxanthines accelerate memory decay

Theophylline and 3-isobutyl-1-methylxanthine, two cyclic nucleotide phosphodiesterase inhibitors, when fed to wild-typeDrosophila adults, cause the rapid decay of learning index after training in a shock-odor learning paradigm. The drugs practically do not affect the olfactory acuity of flies, hence they influence the learning/memory process itself. The time courses of memory decay resemble those of the memory mutantsrutabaga andamnesiac and, to a lesser extent,dunce ² anddunce ^M11. Theophylline further deteriorates the learning performance ofdunce ^M11. Biochemical characterization of the inhibition of the two major phosphodiesterase isoenzymes inDrosophila by theophylline predicts only a slight inhibition of these enzymesin vivo, in accordance with the unchanged level of cAMP in wild-type fly heads during drug feeding. 8-Phenyltheophylline, an adenosine receptor antagonist in mammals, slightly retards memory decay in the wild-type. It is suggested that alkylxanthines induce memory decay inDrosophila by interfering with cAMP dynamics at more than one point of its metabolism.This work was supported by Grants OTKA and OKKFT Tt to P.F.     

Molecular Manipulations of Extracellular Superoxide Dismutase: Functional Importance for Learning

Extracellular superoxide dismutase (EC-SOD) controls the availability of extracellular superoxide (O ₂ ^- ), which is important for a variety of physiological pathways, including the primary means of inactivating nitric oxide (NO). The role of EC-SOD in neurobehavioral function has been until now unexplored. In the current studies, the phenotypic expression of genotypic alterations of EC-SOD production in mice were characterized for spatial learning and memory. Dramatic impairments in spatial learning in the win-shift 8-arm radial maze were seen in both EC-SOD knockout mice and EC-SOD overexpressing mice. The EC-SOD overexpressing mice were further characterized as having significant deficits in a repeated acquisition task in the radial-arm maze, which permitted the dissociation of long and short-term learning. Long-term learning was significantly impaired by EC-SOD overexpression, whereas short-term learning was not significantly affected by EC-SOD overexpression. NO systems have been shown to be importantly involved in learning and memory. This may be important in the current studies because EC-SOD has primary control over the inactivation of NO. We found that EC-SOD overexpressing mice were resistant to the cognitive effects of L-NAME (N^G-nitro-L-arginine methyl ester hydrochloride), an NO synthase inhibitor. Decreased NO catabolism in these mice may have served to counter the effects of NOS inhibition by L-NAME. The current finding that EC-SOD levels that were either higher or lower than controls impaired learning demonstrates that the proper control of brain extracellular (O ₂ ^- ) may be more vital than merely reduction of brain extracelluar (O ₂ ^- ) in maintaining adequate learning function.     

Platelet interactions with calcium-phosphate-coated surfaces

Many studies have shown that calcium-phosphate (CaP)-coated endosseous implants exhibit more peri-implant bone formation and bone contact at early healing times than uncoated implants. Since the rate of healing is influenced by blood/implant interactions and possibly the degree of blood platelet activation, the aim of this study was to determine whether the topography, microtopography, or the presence of calcium (Ca) and phosphate (PO(4)) ions in the implant surface plays a predominant role in platelet activation. We define the threshold between topography and microtopography as the limit of the scale range of platelets themselves; thus, a microtopographic surface is defined by one which exhibits features 3mum. With the help of four international collaborating laboratories, we prepared 11 titanium and CaP-modified titanium surfaces each with different (micro)topographies and interrogated these surfaces with both platelet adhesion (lactate dehydrogenase activity) and platelet activation (microparticle formation and P-selectin expression) assays. Our results show that: calcium (Ca)- and phosphate (PO(4))-containing surfaces of increasing surface microtopographical complexity exhibit increasing platelet activation; surfaces with similar surface microtopographies show similar levels of platelet activation regardless of the presence of Ca and PO(4) in the surface; and that surface microtopography is responsible for platelet activation rather than the presence of Ca and PO(4) in the surface.     

The effect of immunotherapy on eosinophil accumulation and production of eosinophil chemotactic activity in the lung of subjects with asthma during natural pollen exposure

Two groups of birch pollen--allergic patients with seasonal rhinoconjunctivitis and asthma were followed during two consecutive birch-pollen seasons, one group, N = 10, during a season with high pollen load, and one group, N = 15, during a season of low pollen load. Half the patients were treated with immunotherapy (IT) for 3 and 4 years, respectively. The other half of the patients served as control group (non-IT). Bronchoalveolar lavage (BAL) was performed once before each season and once during the pollen season. Eosinophil (EOS) numbers in BAL were increased (p less than 0.01) during the season with high pollen load but not in the season with a low pollen load, and this increment was absent in the IT-treated group. Also, the EOS cationic protein levels were raised in the non-IT-treated group during the season with a high pollen load. The levels of EOS and neutrophil chemotactic activity were raised in BAL in both seasons in the non-IT-treated group compared with the IT-treated group (p less than 0.02, p less than 0.003, p less than 0.04, and p less than 0.005 in high- and low-load pollen season, respectively). Serum and BAL eosinophil chemotactic activity (ECA) were positively correlated (p less than 0.001). We conclude that there is an influx of active EOSs into the lung of pollen-allergic patients with asthma during a pollen season, which may be abrogated by IT. Furthermore, the generation of ECA appears to be an extremely sensitive marker of antigenic exposure, and the potent inhibition of the generation of ECA by IT may provide a clue as to the mechanism of this treatment.     

Failure of primary breast cancer neoangiogenesis to predict pattern of distant metastasis

In the present study, the primary tumor angiogenesis characteristics of 81 stage IV previously untreated breast cancers with synchronous metastasis to different distant sites (10 patients with soft tissue metastases, 31 with bone metastases, and 40 with visceral metastases) were analyzed. The primary intratumor microvessel density was assessed by immunohistochemical assay on paraffin-embedded primary tumor samples, using a monoclonal anti-CD34 antibody. The mean primary intratumor microvessel density (at 400× fields) was 78±39 (SD) microvessels per field. The microvessel density was not significantly related to the main clinical/pathological features of the tumor (age, cytohistological grade, DNA ploidy, diameter, and receptor status). The percentage of tumor cases with high primary intratumor microvessel density (cut-off median value of the series 73±39 microvessels/field) did not significantly differ in patients with bone, soft tissue, or visceral metastatic disease. Aanalysis of clinical outcome showed a significantly shorter time to progression and overall survival for patients with visceral metastases (P<0.001 and P<0.0002 by log-rank, respectively). Presence of visceral metastases was confirmed to be the only independent prognostic factor related to a worse TTP (hazard risk 2.15, 95% confidence interval 1.14–4.03, P<0.02) and overall survival (hazard risk 1.81, 95% confidence interval 0.98–3.35, P<0.06) by multivariate analysis. In conclusion, the assessment of neoangiogenesis of primary breast cancer by CD34 expression does not provide information predictive of different distant sites of metastasis. Received: 15 June 2001 / Accepted: 12 September 2001     

Ratio of shear to load ground-reaction force may underlie the directional tuning of the automatic postural response to rotation and translation

This study sought to identify the sensory signals that encode perturbation direction rapidly enough to shape the directional tuning of the automatic postural response. We compared reactions to 16 directions of pitch and roll rotation and 16 directions of linear translation in the horizontal plane in freely standing cats. Rotations and translations that displaced the center of mass in the same direction relative to the feet evoked similar patterns of muscle activity and active ground-reaction force, suggesting the presence of a single, robust postural strategy for stabilizing the center of mass in both rotation and translation. Therefore we postulated there should be a common sensory input that encodes the direction of the perturbation and leads to the directional tuning of the early electromyographic burst in the postural response. We compared the mechanical changes induced by rotations and translations prior to the active, postural response. The only consistent feature common to the full range of rotation and translation directions was the initial change in ground-reaction force angle. Other variables including joint angles, ground-reaction force magnitudes, center of pressure, and center of mass in space showed opposite or nonsignificant changes for rotation and translation. Change in force angle at the paw reflects the ratio of loading force to slip force, analogous to slips during finger grip tasks. We propose that cutaneous sensors in the foot soles detect change in ground-reaction force angle and provide the critical input underlying the directional tuning of the automatic postural response for balance.     

Gene profiling reveals increased expression of uteroglobin and other anti-inflammatory genes in glucocorticoid-treated nasal polyps

BACKGROUND: Treatment with local glucocorticoids (GCs) decreases symptoms and the size of nasal polyps. This might depend on the downregulation of proinflammatory genes, as well as the upregulation of anti-inflammatory genes. OBJECTIVE: We sought to identify GC-regulated anti-inflammatory genes in nasal polyps. METHODS: Affymetrix DNA microarrays were used to analyze the expression of 22,283 genes in 4 nasal polyps before and after local treatment with fluticasone (400 microg/d). Expression of uteroglobin and mammaglobin B was analyzed with real-time PCR in 6 nasal polyps and in nasal biopsy specimens from 6 healthy control subjects. RESULTS: Two hundred three genes had changed in expression in treated polyps, and 139 had known functions: 54 genes were downregulated, and 85 were upregulated. Genes associated with inflammation constituted the largest single functional group. These genes affected key steps in inflammation (eg, immunoglobulin production; antigen processing and presentation; and the chemoattraction and activation of granulocytes, T cells, and B cells). Several proinflammatory genes were downregulated. In contrast, some anti-inflammatory genes were upregulated. The gene that increased most in terms of expression was uteroglobin. This was confirmed with real-time PCR. By contrast, expression of uteroglobin was lower in untreated polyps than in healthy nasal mucosa. Immunohistochemical investigation showed staining of uteroglobin in the epithelium and in seromucous glands in control subjects and in nasal polyps. CONCLUSION: Upregulation of anti-inflammatory genes, such as uteroglobin, might contribute to the effects of local treatment with GCs in nasal polyps.     

Family history of cardiovascular disease is associated with cardiovascular responses to stress in healthy young men and women.

Heightened cardiovascular stress responsivity is associated with cardiovascular disease, but the origins of heightened responsivity are unclear. The present study investigated whether disturbances in cardiovascular responsivity were evident in individuals with a family history of cardiovascular disease risk. Data were collected from 60 women and 31 men with an average age of 21.4 years. Family history of cardiovascular disease risk was defined by the presence of coronary heart disease, hypertension, diabetes or high cholesterol in participants' parents and grandparents; 75 participants had positive, and 16 had negative family histories. Systolic and diastolic blood pressure (BP), heart rate and heart rate variability were measured continuously for 5 min periods at baseline, during two mental stress tasks (Stroop and speech task) and at 10-15 min, 25-30 min and 40-45 min post-stress. Individuals with a positive family history exhibited significantly greater diastolic BP reactivity and poorer systolic and diastolic BP recovery from the stressors in comparison with family history negative individuals. In addition, female participants with a positive family history had heightened heart rate and heart rate variability reactivity to stressors. These effects were independent of baseline cardiovascular activity, body mass index, waist to hip ratio and smoking status. Family history of hypertension alone was not associated with stress responsivity. The findings indicate that a family history of cardiovascular disease risk influences stress responsivity which may in turn contribute to risk of future cardiovascular disorders.