Actin-dependent anterograde movement of growth-cone-like structures along growing hippocampal axons: a novel form of axonal transport?

In time-lapse video recordings of hippocampal neurons in culture, we have identified previously uncharacterized structures, nicknamed "waves," that exhibit lamellipodial activity closely resembling that of growth cones, but which periodically emerge at the base of axons and travel distally at an average rate of 3 microm/min. In electron micrographs of identified waves, the cortical region of the axon appears expanded to either side, forming lamellipodia like those at growth cones. No other gross differences were noted in the ultrastructural features of the axon shaft at the site of a wave. Immunocytochemistry revealed that waves contain a marked concentration of F-actin, GAP-43, cortactin, and ezrin or a related protein, constituents that are also concentrated in growth cones. Treatment with the actin-disrupting agent cytochalasin B caused a reversible collapse of lamellipodia and cessation of the forward movement of individual waves along the axon, indicating that their anterograde transport is dependent on intact actin filaments. Treatment with the microtubule-depolymerizing agent nocodazole led to a rapid disorganization of wave structure and a subsequent suppression of wave activity that may reflect a role of microtubules in actin organization. The results suggest that actin and other cytoskeletal components concentrated in growth cones may be transported together as growth-cone-like structures from the cell body to the axon tip via an actin-dependent mechanism.     

Women's experiences of treatment of depression: Medicalization or empowerment?

An interview study was conducted in which women's experiences of diagnosis and treatment for depression were explored. Nine women (aged 19–66 yrs) who had been diagnosed by a physician participated in the study. Topics explored in the interview included how women came to be diagnosed as depressed, how treatment was experienced, how they understood the causes of their depression, and how being diagnosed had affected their view of themselves and their futures. Analysis involved a thematic approach guided by the topics addressed in the interview. The women's accounts also were analyzed with respect to the themes of medicalization and empowerment. All of the participants gave medicalized accounts of their depressive experiences, which were characterized by biomedical explanations and identification of anti-depressant drugs as beneficial in alleviating their distress. Based on this analysis of the women's accounts, it is concluded that a medicalized understanding and treatment of women's depressive experiences cannot readily co-exist with personal empowerment. Suggestions are made for developing strategies for treatment of women's depressive experiences that offer the benefits of medicalization without precluding the possibility of personal empowerment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Incorporation of europium (Ⅱ) nanostructures into the channels of mesoporous silicon oxy-nitride for enhanced photoluminescence

Divalent europium(Ⅱ)-doped mesoporous silicon oxy-nitride materials, as a novel type of nanoscopic photoluminescent material, are studied in which the optically active luminescent centers are isolated within the pores, Colorless and transparent blue emitting luminous Eu~(2+)-doped mesoporous silicon oxy-nitride materials were prepared from mesoporous silica via impregnation, nanocasting and nitrogen-assisted carbothermal reduction and nitridation method. The morphology and porosity of the silica remain unchanged during the synthesis process as revealed by SEM images and by nitrogen sorption studies. Photoluminescence studies reveal a strong blue emission band for Eu~(2+) centered at 425 nm with a quantum efficiency of 47%. The luminescent intensity is greatly influenced by the amount of co-dopant, Al~(3+) ions.     

Multicellular resistance: another mechanisms of pleiotropic resistance?

Cells cultured as spheroids present an heterogeneity similar to that of tumours in vivo. In the spheroid peripheral layers, cells are proliferating, deeper cells are non-cycling, when in the aggregate centre, cells from often a necrotic core. A multicellular resistance appears in spheroids, it is a result of the cell contact to other cells (homogeneous or heterogeneous cells) and/or to the extracellular matrix. The mechanism of this resistance is not known, nevertheless, it can be hypothesised to be linked to the spheroid centre hypoxia, to the quiescence of a large fraction of the cell population and to the apoptosis inhibition due to the cell contact. The "classical" or "unicellular" mechanisms of resistance, as mdr1, MRP, can coexist with the multicellular resistance, but are not responsible for this resistance. The spheroid model of culture is a good opportunity to study a resistance type which looks close to the tumour resistance found in vivo in mice and in patients. A new class of therapeutic molecules appears that can reverse this multicellular resistance, inhibit tumours growth and preclude metastases. The principal mechanism of action of this new pharmacological class appears to be the disruption of the intercellular adhesion forces. Preliminary results obtained with these compounds in patients are promising.     

Paranasal sinuses: only one of nature's games?

BACKGROUND: Many theories exist concerning the function of paranasal sinuses, but it is rather difficult to definitively name the right one. Despite the fact that many of them have been proved to be wrong, they are still used. THEORIES: Galen postulated 2000 years ago that they were "porous bones", which helped with weight reduction. Like Galen's theory, most of the others have been refuted as well. A list of these refuted theories covers a range of postulated functions including a relative warming or moistening of the breath, protection against high pressure in the nasal region when sneezing, paranasal sinuses as a place of efficient mucus production, or an aid for smelling, similar to the ethmoidal cells of the porcupine. Others include an isolated function for protection against cold climates and an aid for formulating sound by acting as a resonance chambers. CONCLUSIONS: Two theories still remain. One says that the paranasal sinuses are only the result of the evolutionary processes that have taken place in the skull during human development. The other theory explain that the form of the paranasal sinuses exists through the influence of the forces created during the act of chewing. Small cavities appear as a result of the minimal energy created, and these cavities can be found in the form of paranasal sinuses.     

Normality is Control of Impulses?: Comment.

Comments on a paper by Schoben (American Psychologist, 1957, 12, 183-189). The author of this comment discusses impulse control, particularly antisocial impulses and its relation to anticipatory capacity. The author feels the considerations he discusses suggest that one does not do justice to the issue of impulse control by primarily stressing anticipatory capacity and suggesting that some form of conformity is avoided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Uterine allergy: a cause of preterm birth?

OBJECTIVE: To identify the origin of eosinophils in cases of eosinophil-associated preterm delivery. METHODS: From an established set of 465 consecutive non-anomalous singleton infants delivered at 22-32 weeks' gestation, we retrieved 161 cases of preterm delivery following spontaneous onset of preterm labor, 78 cases with maternal preeclampsia, 33 cases of abruption, and 193 cases of premature rupture of membranes (PROM). Charts were reviewed, and the placenta, umbilical cord, and membranes were examined histologically. In cases with extravascular eosinophils showing evident gradient toward the amniotic cavity, the origin of the eosinophils (fetal or maternal) was determined by the proximity to fetal or maternal vessels. RESULTS: Histologic evidence of an eosinophilic gradient toward the amniotic cavity was present only in the fetal (including umbilical cord and chorion) compartments. This eosinophilic gradient was present in 19% (90 of 465) of preterm delivery cases and was significantly more common in cases of PROM (54 of 193, 28%) and preterm labor (34 of 161, 21%) than abruption (two of 33, 6%) and preeclampsia (none of 78) (P < .001). In 84 of 90 cases (93%), the eosinophilic gradient was present along with multiple histologic indicators of acute intrauterine inflammation. CONCLUSION: An eosinophilic gradient toward the amniotic cavity, present in nearly a fifth of cases of preterm delivery, is probably of fetal origin, making it unlikely that a maternal "allergy-like" mechanism is a cause of preterm delivery.     

Hypophosphatasia: a developmental anomaly of alkaline phosphatase?

This report deals with quantitative and qualitative investigations of alkaline phosphatase in two unrelated infants with the severe infantile form of hypophosphatasia. Both affected infants had no detectable leukocyte alkaline phosphatase activities and both sets of parents and one sibling tended to have low but variable leukocyte enzyme activities. Normal duodenal juice alkaline phosphatase activity was present in the one patient in whom it was measured and a wide range of variation in enzymic activity was observed in the stools. There was no significant difference in the stool enzyme activity between both patients with hypophosphatasia (42.01 +/- 9.77 U) and control infants (40.55 +/- 6.29 U). However, the heterozygous parents had values significantly lower than the control adults (2.10 +/- 0.47 as compared with 19.10 +/- 4.44 U). Intestinal bacteria did not contribute significantly to the stool alkaline phosphatase activity. Enzyme activity was present in the bile of one of the patients and nearly absent in that of the other. Three "inducers" of alkaline phosphatase were given to both patients (phenobarbital, vitamin A, and corticosteroid). No clinical improvement or rise in serum alkaline phosphatase activity was observed during the trial of therapy with these agents. However, a significant increase in the activity of serum acid phosphatase was demonstrated during the course of vitamin A administration, suggesting an in vivo action of vitamin A on the lysosomes through decreasing the stability of the membrane and releasing acid phosphatase to the serum. Quantitative determination of tissue alkaline phosphatases from autopsy tissues was highly variable: no activity was found in bone, lungs, or spleen of either infant; there was a discrepancy in liver and kidney alkaline phosphatase values (zero in one patient and present in the other) and activity was present in the intestinal mucosa of both. Qualitative analysis of kidney, liver, and intestinal alkaline phosphatase revealed some differences between the patients and control subjects in heat inactivation and phenylalanine inhibition (Table 3). Starch gel electrophoresis of the liver preparation of one patient disclosed a single band which had greater mobility than that of six control subjects matched for age. Liver extracts from a premature and from full term newborns showed two bands. The single band of the patient's liver enzyme corresponded to the newborn's fast moving component. In addition, the intestinal enzyme prepared from the same patient had an extra band when compared with age-matched control subjects.     

Fear of contagion: a response to stress?

Alterations of neutrophil functions by tobacco products may play a central role in the pathogenesis of periodontal diseases and several smoking-related systemic diseases. In the present study, we examined the in vitro effects of cigarette smoke on neutrophils at times and concentrations that may be encountered during smoke exposure. We measured the level of smoke exposure in the in vitro system by measuring the levels of nicotine and comparing these to levels in the oral cavity in smokers before and after smoking. We examined both the unstimulated and stimulated release of 2 oxidative burst products: superoxide (O-2) and hydrogen peroxide (H2O2). Salivary washings were collected from 7 smokers (> 1 pack/day) before smoking a cigarette. Immediately after they smoked a cigarette, a second set of washings was collected. In vitro exposure to smoke involved incubating aliquots of neutrophils in phosphate-buffered saline for 1 to 5 minutes. Nicotine and cotinine levels were quantitated using gas chromatography, with detection by electron impact mass spectrometry. Peripheral neutrophils were isolated from medically healthy non-smoking volunteers via a double-density gradient technique and incubated in vitro with whole cigarette smoke for 0 to 5 minutes. Phorbol myristate acetate (PMA; 10(-7) M) was used to stimulate half of the cell aliquots. Superoxide generation was assessed through the superoxide dismutase (SOD) inhibitable reduction of ferricytochrome c. H2O2 production was assessed through the H2O2-dependent breakdown of dichlorofluorescin diacetate to its fluorophore and measured by flow cytometry. There was a marked elevation in salivary nicotine concentration from before smoking (mean: 80.8 ng) to after smoking (mean 1,685 ng/mL). In the in vitro smoke box system, there was a time-related elevation in nicotine from 1 to 5 minutes (50-->136 ng/mL). In PMA-stimulated cells exposed to smoke, there was a time-related inhibition of both superoxide and H2O2 production. However, in unstimulated cells exposed to smoke, there was a time-related increase in the release of superoxide and H2O2. A novel finding in unstimulated cells exposed to smoke was that there appeared to be 2 distinct populations of cells--one of "high" H2O2 producers and one of "low" H2O2 producers. The proportion of high H2O2 producers increased relative to smoke exposure. The relative production of H2O2 in the unstimulated high producers was comparable to PMA-stimulated cells at 5 minutes. This release of superoxide and H2O2 in unstimulated cells exposed to smoke may alter the pathogenic processes both in periodontal diseases and other systemic diseases.     

Inflammatory fibrosarcoma: another imitator of Hodgkin's disease?

We report a case of inflammatory fibrosarcoma occurring in a 49 year-old man, that manifested with distinct multinodular masses in the mesentery. Histologically, the lesion was characterized by spindle fibroblast-like cells, histiocytes, pool of lymphocytes and eosinophils, abundant fibrous to hyaline stroma, and numerous "ganglion" cells. Of special interest was the presence of large multinucleated tumor cells which displayed optically clear nuclei and prominent nucleoli, bearing a deceitful resemblance to the diagnostic Reed Sternberg cells of Hodgkin's disease. The differential diagnosis between the two conditions rests on the evaluation of the appropriate clinical background, as well as on an in-depth assessment of the basic pathologic features. Immunohistochemical reactivity of spindle and ganglion cells for actin along to complementary negativity for CD15, and CD30 further assists in separating the two conditions.     

Hindsight bias: A by-product of knowledge updating?

With the benefit of feedback about the outcome of an event, people's recalled judgments are typically closer to the outcome of the event than their original judgments were. It has been suggested that this hindsight bias may be due to a reconstruction process of the prior judgment. A model of such a process is proposed that assumes that knowledge is updated after feedback and that reconstruction is based on the updated knowledge. Consistent with the model's predictions, the results of 2 studies show that knowledge after feedback is systematically shifted toward feedback, and that assisting retrieval of the knowledge prior to feedback reduces hindsight bias. In addition, the model accounts for about 75% of cases in which either hindsight bias or reversed hindsight bias occurred. The authors conclude that hindsight bias can be understood as a by-product of an adaptive process, namely the updating of knowledge after feedback. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accuracy of interpersonal perception: A general trait?

After viewing filmed interviews, judges made predictions in regard to behavior which would be subsequent to certain stated conditions, personality traits, how an opinion might be expressed by the observed S, and how the observed S might complete certain sentences. A general ability to perceive others accurately was isolated, and seen to be related to the factor of "sensitivity to the generalized other" and "interpersonal sensitivity." The relationship to related empirical and theoretical work is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Recall of interrupted tasks under stress: A phenomenon of memory or of learning?

The study proposed to answer three questions: "1. Is superior recall of successes in an intelligence test situation (S-recall) a function of selective forgetting (repression) of failures or selective learning in favor of successes? 2. Is superior recall of failures in this situation (F-recall) a function of selective remembering or selective learning in favor of failures? 3. Is there a mnemonic reaction to the test as a whole?" Findings indicate that: "1. Both the S- and f-recall tendencies were due to a selective learning rather than a selective remembering mechanism. 2. A repression was demonstrated for S-recallers with regard to the stress situation as a whole. 3. A comparable process of enhanced retention of the total stress situation was not demonstrated for F-recallers; rather the effect here was due to enhanced registration." Implications of results are discussed. It is suggested that "experimental tests of repression… fulfill a criterion of cognitive relevance of test materials." 23 references. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solidification of Metallic Alloys: Does the Structure of the Liquid Matter?

Metallurgical and Materials Transactions A - In 1952, Frank (Proc R Soc Lond Ser-Math Phys Sci 215:43–46, 1952) already postulated that Icosahedral Short Range Order (ISRO) of atoms in the...     

Implicit learning differences: A question of developmental level?

A. S. Reber's (see record 1993-32264-001) proposition that the implicit learning system should demonstrate invariance of intellectual level (IQ) was examined by comparing 20 children with intellectual disability (mean mental age [MA]?=?approximately 5.8 years) with 20 intellectually gifted children (mean MA?=?approximately 12.4 years) of similar chronological age (CA; approximately 9.5 years). Implicit learning was assessed using a task involving covariation of 2 incidental cues. Explicit learning was assessed using a task of similar logical structure. Contrary to the IQ-invariance proposition, implicit learning as well as explicit learning varied with intellectual level. A secondary aim was to distinguish the contributions of CA, IQ, and MA to implicit learning. This was done by combining the samples of children in the present study with 2 samples of younger and older children of average ability from a study by M. Maybery, M. Taylor, and A. O'Brien-Malone (see record 1996-00932-001). Analyses showed that MA is critical to implicit learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ingestion of caustic hair relaxer: is endoscopy necessary?

Hair relaxer, a commercially available alkaline product, is commonly the offending agent in caustic ingestion. These patients often experience oral cavity and facial burns; however, no clinically significant esophageal injuries have been reported. Therefore, we questioned the therapeutic and economic efficacy of the "standard treatment protocol" that includes hospitalization and endoscopic evaluation. Twenty-six patients over a 7-year period presented to our institution having ingested hair relaxer. Presenting signs and symptoms, esophageal findings, and cost of the standard treatment protocol were reviewed. Also, we analyzed the caustic potential and current packaging of hair relaxer. Our findings support modifications in the standard treatment protocol for hair relaxer ingestion including elimination of hospitalization and endoscopy in most patients. We also question compliance with childproof packaging laws and suggest avenues for prevention of hair relaxer ingestion.     

Origin of laparoscopy: coincidence or surgical interdisciplinary thought?

The history of laparoscopy illustrates the interaction between the many areas of medicine and technology; in fact, the development of that technique is a cumulative effort of internists, gynecologists, and surgeons. At the beginning of our century, however, neither group was particularly open to the idea of scholarly exchange. In this respect, an early pioneer of laparoscopy, Georg Kelling (1866-1945) of Dresden and the story surrounding the invention of the laparoscopy are interesting exceptions. Although Kelling regarded himself a surgeon, he devoted a great deal of energy to the development of "nonsurgical" methods of treatment. He spent a great part of his life determining stomach capacity, constructing a semiflexible tube endoscope (straightened after the insertion), and attempting to alleviate gastrointestinal bleeding by means of high-pressure pneumoperitoneum (lufttamponade). To observe the effects of insufflation on abdominal organs, Kelling introduced a cystoscope into the abdominal cavity. In fact, the invention of "celioscopy" or laparoscopy (1901) can be called a synthesis of Kelling's work with insufflation and his fascination with endoscopy.     

Predictive tests of radiocurability: towards a custom-made radiotherapy?

Up to now, radiation oncologists had at their disposal only a number of well-known histological and clinical factors in order to define the optimal dose which should be delivered to a given tumor. Recently, radibiological studies have suggested additional parameters which may play a major role in tumor radiocurability. These parameters are: the number of clonogenic cells, intrinsic radiosensitivity, hypoxia and proliferation kinetics. "Predictive" tests are being developed and evaluated for each of these parameters. The more advanced studies deal with intrinsic radiosensitivity; preliminary data show impressive variations in radiosensitivity within groups of clinically "homogeneous" tumors. Should these tests prove to be reliably predictive of radiocurability, it will be possible, in the near future, to propose to any given patient a "custom-made radiotherapy" adapted to the precise features of his or her tumor.     

Emotional modulation of the attentional blink: Is there an effect of stress?

Individuals are often unable to identify the second target (T2) of two when it is presented within 500 ms after the first target (T1). This “attentional blink” (AB) is attenuated by an emotionally arousing T2. Stress is known to affect cognitive performance, in particular for emotional material. In the present study, we asked whether (a) an emotional T2 reduces the AB when preceded by an emotional T1 and (b) the emotional modulation of the AB is affected by stress. Participants were presented neutral and aversive words as T1 and T2 in rapid serial visual presentation after they were exposed to stress (socially evaluated cold pressor test) or a control condition in a crossover manner. Our results indicate that an aversive T1 extends the AB. Aversive T2 attenuated the AB in the presence of a neutral, but not an aversive, T1. Stress-enhanced T2 detection and high cortisol responses to stress reduced the AB. However, neither stress nor cortisol interacted with the emotionality of the target words. In summary, these findings point to a strong impact of emotional factors on early perceptual experiences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Transsaccadic representation of layout: What is the time course of boundary extension?

How rapidly does boundary extension occur? Across experiments, trials included a 3-scene sequence (325 ms/picture), masked interval, and repetition of 1 scene. The repetition was the same view or differed (more close-up or wide angle). Observers rated the repetition as same as, closer than, or more wide angle than the original view on a 5-point scale. Masked intervals were 100, 250, 625, or 1,000 ms in Experiment 1 and 42, 100, or 250 ms in Experiments 2 and 3. Boundary extension occurred in all cases: Identical views were rated as too "close-up," and distractor views elicited the rating asymmetry typical of boundary extension (wider angle distractors were rated as being more similar to the original than were closer up distractors). Most important, boundary extension was evident when only a 42-ms mask separated the original and test views. Experiments 1 and 3 included conditions eliciting a gaze shift prior to the rating test; this did not eliminate boundary extension. Results show that boundary extension is available soon enough and is robust enough to play an on-line role in view integration, perhaps supporting incorporation of views within a larger spatial framework. (PsycINFO Database Record (c) 2010 APA, all rights reserved)