Immunologic analysis of monoclonal and immunoglobulin E antibody epitopes on natural and recombinant Amb a 1

Background Amb a 1 is the major allergen from ragweed pollen and more than 90% of ragweed‐allergic patients react with this protein. Although Amb a 1 was cloned and sequenced in 1991, little is known of the specificity of anti‐Amb a 1 antibodies or of the immunologic properties of the recombinant allergen. Objective To compare binding of monoclonal antibodies (mAb) and IgE antibodies to purified natural Amb a 1 (nAmb a 1) and recombinant Amb a 1 (rAmb a 1). Methods Binding of a panel of anti‐Amb a 1 mAb and IgE antibodies to nAmb a 1 or rAmb a 1 was compared by immunoblotting. Chimeric ELISA was used to measure specific IgE to these allergens using 89 ragweed‐allergic sera from Austria, Italy, Canada and the United States. Results The 8 mAb bound to a 38 kDa Amb a 1 band in ragweed pollen extract and a subset of 5 mAb also bound to the 26 kDa chain of nAmb a 1. A two‐site ELISA was developed using a mAb pair, which was ～10‐fold more sensitive to rAmb a 1. There was a significant correlation between IgE antibody binding to nAmb a 1 and rAmb a 1 (n=89, r=0.79, P<0.001). A subset of ～40% of patients showed greater reactivity to nAmb a 1 than to rAmb a 1. Conclusions The data suggest that there is less reactivity of human IgE to rAmb a 1 compared with nAmb a 1. The development of more sensitive, quantitative ELISA for Amb a 1 will require the production of new mAb especially directed against nAmb a 1.     

The effect of cash and other financial inducements on the response rate of general practitioners in a national postal study.

BACKGROUND: Low response rates are acknowledged as a potential source of bias in survey results. Response rates are a particular problem in surveys of GPs. Thus, the methods used to encourage response to mailed surveys and the influence of inducements in maximizing response rates are fundamental issues to be examined when addressing the problem of response bias. AIM: To increase the overall response rate to a national study of GPs and to explore the effects of financial and non-financial inducements on response rates. METHODS: Two mailing waves of a postal questionnaire to a 20% random sample of all GPs in England and Wales had achieved a 33% response rate. For the third mailing wave, the non-responding GPs were then divided into a control group, a group who were offered a donation to charity to complete the questionnaire and a group who were offered cash. The charity and cash groups were further subdivided into 5 pounds and 10 pounds groups to assess the effect of the size of the inducement offered. For the control group, a fourth wave was sent the offer of a 5 pounds or 10 pounds incentive. RESULTS: Response was positively affected by the offer of an inducement. Cash, however, had a more substantial effect than the offer of a donation to charity. Older GPs were less likely to participate overall, whereas male GPs were more likely to respond to a cash inducement. Doctors who had seen more patients were less likely to reply earlier and were more likely to respond to the offer of cash. CONCLUSIONS: Primary care is going through many changes, some of which have increased the workload of the GP. It may now be that, to achieve the response rates needed to validate policy-related research, the offer of inducements will become a necessary part of the research process.     

Nonlinear encoding of tactile patterns in the barrel cortex

Cells in the rodent barrel cortex respond to vibrissa deflection with a brief excitatory component and a longer suppressive component. The response to a given deflection is thus scaled because of suppression induced by a preceding deflection, causing the neuronal response to be linked to the temporal properties of the peripheral stimulus. A paired-deflection stimulus was used to characterize the postexcitatory suppression and a 3-deflection stimulus was used to investigate the nonlinear response to patterns of whisker deflections in barbiturate-anesthetized Sprague-Dawley rats. The postexcitatory suppression was not dependent on a sensory-evoked action potential to the first deflection, implying that it is likely a subthreshold property of the network. The suppression induced by a deflection served to suppress both the excitatory and suppressive components of a subsequent neuronal response, thus effectively disinhibiting it. Two different response properties were observed in the recorded cells. Approximately 65% responded to a vibrissa deflection with an excitatory component followed by a suppressive component and 35% responded with excitation, suppression, and a subsequent rebound in excitation. Based on these observations of postexcitatory dynamics, a prediction method was used to estimate neuronal responses to more complex stimulus trains. Using the 2nd-order representation obtained from the paired-deflection stimulus, responses to general periodic deflection patterns were well predicted. A higher cutoff frequency was predicted for rebound cells compared with cells not exhibiting rebound excitation, consistent with experimental observations. The method also predicted the response of neurons to a random aperiodic deflection pattern. Therefore the temporal structure of cortical dynamics after a single deflection dictates the response to complex temporal patterns, which are more representative of stimuli encountered under natural conditions.     

Thought disorder in schizophrenia: impairment in contextual processing via integrative failures in cognition

Formal thought disorder is a critical dysfunction in schizophrenia whose cause remains uncertain, but whose explanation may greatly further our understanding of the disease. Thought disorder in patients with schizophrenia has been hypothesized to involve a disturbance in the internal representation of context. Positive symptoms of schizophrenia attributable to thought disorder display a lack of organization that may be accounted for by an absence of normal contextual processing occurring within the operations of the executive system. But the precise nature and pervasiveness of the deficient cognitive operation remain undistinguished. It is proposed here that the assimilatory functions of the brain appear to lack the ability to perform a particular type of integrative operation when presented with heterogeneous information. This deficit involves committing cognitive misattributions through a confusion of mental terms via a process in thought analogous to a linguistic failure to correctly interpret deictic referents. Both proposed deficits in mental deixis and analogous “metarepresentational” deficits in schizophrenia potentially involve a failure to draw information for a conclusion from a separate framework of relations in integrative fashion. These deficits appear to involve a failure to take an interpreted piece of information as an output from a particular mental task and incorporate it into a new operational scheme, and a central attribute to the deficit is that there is a loss of an effective or adequate integration of separate strata of information. Potential neurobiological correlates to such a system based on current knowledge about schizophrenia neurocircuitry, as well as implications for testing, are also discussed.     

The reduced responsiveness of neurones in nucleus reticularis gigantocellularis following their excitation by peripheral nerve stimulation.

1. Post-stimulus histograms of neuronal activity, constructed from extracellular recordings in decerebrate, decerebellate cats, have been used to investigate the responsiveness of neurons in nucleus reticularis gigantocellularis following their excitation by a peripheral nerve stimulus. 2. The response to a testing stimulus applied to a peripheral nerve was depressed following the response to a conditioning stimulus applied to the same or a different peripheral nerve. This reduction in responsiveness was maximal within 50 msec of the peak of the response to the conditioning stimulus. Response latencies to the testing stimulus were increased during the period of reduced responsiveness. 3. Responsiveness to a peripheral nerve stimulus was also reduced following a spontaneous or an antidromically evoked spike, but this effect was weaker and much shorter-lasting than that following a nerve-evoked spike. Thus, the reduced responsiveness cannot be solely due to phenomena which are an inevitable consequence of an action potential in the neurone. 4. In spontaneously firing neurones, the duration of the reduced responsiveness to a testing stimulus generally outlasted the depression of spontaneous activity which often followed an excitation evoked by a peripheral nerve conditioning stimulus. 5. The reduction in responsiveness to a testing stimulus applied to the same nerve as the conditioning stimulus was greater and longer-lasting than that to a testing stimulus applied to a different nerve. 6. When stimuli were applied to one nerve at a relatively high rate, the neurone became much less responsive to that input, but simultaneously became more responsive to low rate stimulation of other nerves. 7. It is concluded that the greater part of the reduced responsiveness is due to events occurring on the input pathway to a reticular neurone, or possibly in the region of the afferent endings on its dendrites. These processes may allow selective changes in responsiveness to different inputs, and enable the units to act as novelty detectors.     

Modulation of adrenergic receptors during aging

In aging there is not only a reduced density of adrenergic receptors but also a reduced capacity to adapt these receptors to a changing neuronal input or hormonal environment. A reduced density of receptors presumably would result in a decreased ability of aged individuals to respond to stimulation of these receptors, and a reduced ability to modulate these receptors would result in a decreased capacity to adapt their responses to a changing internal or external environment. Future studies should be directed at the genomic mechanisms that control receptor synthesis.     

双向杂交系统：研究蛋白质间相互作用的新手段

双向杂交系统：研究蛋白质间相互作用的新手段王巍（中国医学科学院基础医学研究所医学分子生物学国家重点实验室，北京１００００５）ＡｂｓｔｒａｃｔＴｈｅｔｗｏ－ｈｙｂｒｉｄｓｙｓｔｅｍｉｓａｙｅａｓｔｇｅｎｅｔｉｃａｓａｙｆｏｒｄｅｔｅｃｔｉｎｇｐｒｏｔｅ...     

Prevalence of latex sensitization in subjects attending health screening: implications for a perioperative screening

Background Because latex is a common allergen, the rate of latex sensitization may be high in the general population. A major issue would then be to detennine whether a systematic preoperative screening in the general population should be recommended. Objective The purpose of the study was to evaluate the prevalence of latex sensitization in a sample of the general population and to assess the role of possible risk factors. Methods The subjects were 258 people, aged from 20 to 40 yr, visiting a health care centre for a check-up. The protocol included: a questionnaire (occupation, symptoms of atopy, use of latex goods and possible reactions, history of previous surgery), a skin-prick test, and a CAP RAST to latex. Atopy was evaluated by a skin-prick test to common allergens and a Phadiatop® test. Results Some 6.6% of the study group had either a positive skin test or a positive RAST to latex. These subjects had a four-fold higher prevalence of symptoms when wearing gloves. The rate of latex sensitization was higher by fivefold in subjects with a history of reactions to latex goods and by fourfold in atopic subjects. Conclusions Because the rate of latex sensitization is much higher than the anticipated rate of perioperative reactions due to latex allergy, a systematic preoperative screening for latex allergy should not be recommended for adults.     

Saccade-related activity in the primate superior colliculus depends on the presence of local landmarks at the saccade endpoint

Saccade-related discharge in the superior colliculus is greater for saccades made to a spot of light than for saccades in complete darkness. However, it is unclear whether this enhancement is due to the discontinuity of the spot or due to its being a new object of fixation. In these experiments, we examined the saccade-related activity of intermediate-layer neurons in the primate superior colliculus during delayed saccades to the center or corner of a large, bright square, as well as for visual and memory-guided movements to small spots in isolation. The saccade-related discharge for movements made to a local visual landmark present at the time of the saccade, be it a corner of a square or a small spot, was higher than that for saccades made to the center of a square that contained no local visual landmarks within. Moreover, discharge for movements to the center of a square were very similar to that for saccades to blank, dark space. Saccade velocity was similarly dependent on the presence of such a landmark, though less dramatically. The endpoints of saccades directed toward a square's corner were slightly displaced toward the center of the square. Across all neurons, discharge and velocity for saccades to the center of a square increased as the square size was decreased, but were never greater than those for saccades to a small spot of light. These results suggest that both saccade-related discharge in the superior colliculus and saccade metrics are enhanced for movements directed to parts of the visual scene with high contrast, while shifting fixation to a new object is not itself sufficient to elevate discharge and metrics above those of saccades to blank space.     

Specific detection by flow cytometry of histidine-tagged ligands bound to their receptors using a tag-specific monoclonal antibody.

Engineering proteins to contain a histidine (His)-tag has proved to be very useful for the purification and analyses of these molecules. In the present study, we demonstrate that the binding of His-tagged ligands to their receptors may be visualised by flow cytometry making use of a selected monoclonal antibody (mAb) against the His-tag. Employing this method, a recombinant C3a (rC3a) anaphylatoxin with a His-tag at its N-terminus could be shown to bind to C3a receptor (C3aR)-expressing RBL-2H3 transfectants with a half-maximal effective concentration (EC50) of about 3 nM which is well within the range of published affinity constants. Binding of a recombinant interleukin-8 (rIL-8) molecule with a C-terminal His-tag to RBL-2H3 cells which stably express the IL-8 receptors CXCR1 or CXCR2 could also be demonstrated using the tag-specific mAb. Furthermore, aminoterminally tagged C5a molecules of rat or human origin could be shown to bind to the human C5a receptor (C5aR). However, the fluorescence signal of the binding of rat rC5a to the human C5aR was distinctly higher over a wide range of ligand concentrations than the signal of human rC5a binding although both ligands were equally potent in the induction of chemotaxis in C5aR-expressing cells. Thus, the tag-specific mAb was able to interfere with the binding of human but not rat rC5a to the human C5aR. This observation is in agreement with the hypothesis of a two binding site model for the interaction of human C5a with its receptor whereas a different binding mode may apply for rat C5a. Our data demonstrate that the selected His-tag specific mAb may be a valuable tool for the visualisation of the binding of recombinant ligands to their receptors and may also provide useful information on the specific binding properties of the ligands.     

The dialogical self in psychotherapy for persons with schizophrenia: a case study

Schizophrenia often involves a profound experience of one's identity as diminished, which complicates adaptation to the demands of daily life. Within a backdrop of dialogical self-theory, we provide a report of an individual psychotherapy over the course of 4 years that assisted a patient suffering from schizophrenia to move from a state in which few aspects of self were available for internal or external conversation to one in which there was greater accessibility of multiple aspects of self, leading to richer dialogues, improved function, and a better quality of life. It is suggested a primary intervention of the therapist was continuously to offer the client a view of himself that invited him to experience himself in a plausible manner shared with and listened to by another.     

Migration as an Unconscious Search for Identity: Some Reflections on Language,Difference and Belonging

The author addresses some issues regarding patients who relocate and who struggle with adaptation to a new reality. She argues that emigration is a complex psychological phenomenon that requires a therapist to pay special attention to the issue of language, difference and identity, and suggests that the issues of different culture and language in analytic psychotherapy need to be considered as part of a wider cultural context to which we all belong, rather than a specialized area of interest. The paper illustrates, through the clinical example of an East European male patient, that the psychic work of emigration can be understood as a process of integrating splits between pre‐ and post‐migration selves. The author concludes that the analyst needs to let herself be involved as a ‘real person’ to reach the non‐interpretative aspects of the patient's psyche through a mutuality of shared experience to promote a change.     

Presaccadic attention interferes with feature detection

Preparing a saccadic eye movement to a particular spatial location enhances the perception of visual targets at this location and decreases perception of nearby targets prior to movement onset. This effect has been termed the orientation of pre-saccadic attention. Here, we investigated whether pre-saccadic attention influenced the detection of a simple visual feature—a process that has been hypothesized to occur without the need for attention. Participants prepared a saccade to a cued location and detected the occurrence of a “pop-out” feature embedded in distracters at the same or different location. The results show that preparing a saccade to a given location decreased detection of features at non-aimed-for locations, suggesting that the selection of a location as the next saccade endpoint influences sensitivity to basic visual features across the visual field.     

Prediction of MHC class I binding peptides using profile motifs

Peptides that bind to a given major histocompatibility complex (MHC) molecule share sequence similarity. Therefore, a position specific scoring matrix (PSSM) or profile derived from a set of peptides known to bind to a specific MHC molecule would be a suitable predictor of whether other peptides might bind, thus anticipating possible T-cell epitopes within a protein. In this approach, the binding potential of any peptide sequence (query) to a given MHC molecule is linked to its similarity to a group of aligned peptides known to bind to that MHC, and can be obtained by comparing the query to the PSSM. This article describes the derivation of alignments and profiles from a collection of peptides known to bind a specific MHC, compatible with the structural and molecular basis of the peptide-MHC class I (MHCI) interaction. Moreover, in order to apply these profiles to the prediction of peptide-MHCI binding, we have developed a new search algorithm (RANKPEP) that ranks all possible peptides from an input protein using the PSSM coefficients. The predictive power of the method was evaluated by running RANKPEP on proteins known to bear MHCI K(b)- and D(b)-restricted T-cell epitopes. Analysis of the results indicates that > 80% of these epitopes are among the top 2% of scoring peptides. Prediction of peptide-MHC binding using a variety of MHCI-specific PSSMs is available on line at our RANKPEP web server (www.mifoundation.org/Tools/rankpep.html). In addition, the RANKPEP server also allows the user to enter additional profiles, making the server a powerful and versatile computational biology benchmark for the prediction of peptide-MHC binding.     

Ischemic stroke in a young adult with extremely elevated lipoprotein(a): A case report and review of literature

Lipoprotein(a) [Lp(a)] is an apolipoprotein(a) molecule bound to 1 apolipoprotein B-100. Elevated levels of Lp(a) are thought to be an independent risk factor for atherosclerosis and to promote thrombosis through incompletely understood mechanisms. We report a 34-year-old man with an ischemic stroke in the setting of an extremely high Lp(a) level—212 mg/dL. He developed severe carotid artery stenosis over a 6-year period and had thrombus formation post-carotid endarterectomy. To our knowledge, this case is unique because the Lp(a) is the highest reported level in a patient without renal disease. Moreover, this is the first reported case of the youngest individual with a stroke presumably related to development of carotid plaque over a 6-year period. The thrombotic complication after endarterectomy may have been related to the prothrombotic properties of Lp(a). Of note, the Lp(a) level did not respond to atorvastatin but did decrease 15% after aspirin 325 mg was added although his Lp(a) levels were variable, and it is not clear that this was cause and effect. This case highlights the need to better understand the relation between Lp(a) and vascular disease and the need to screen family members for elevated Lp(a). We also review treatment options to lower Lp(a) and ongoing clinical trials of newer lipid-lowering drugs that can also lower Lp(a).     

Becoming a Grandmother: The Third Position

The third position refers to a type of relationship where one is an observer of a relationship rather than a participant. It is the attainment of this position that enables a grandmother to accept her child's partner and the birth of their baby. The type of anxiety aroused in grandmother by the birth will depend on the extent to which she has been able to resolve her oedipal anxieties. My own experience of becoming a grandmother and my work with a patient who became a grandmother during therapy contributed to my understanding of the significance of this life event.     

A variable critical-volume model for normal tissue complication probability

Predicting late-term normal-tissue complication probability (NTCP) after radiotherapy is an important factor in the optimization of conformal radiotherapy. We propose a new NTCP model, based on the properties of the high dose region. The principal assumption of the new model is that a whole-organ complication will occur when the radiation damage to a normal organ volume (a portion of the total organ) exceeds a threshold value. The dose threshold for complications varies with the size of the volume (percent of the total organ). We hypothesize that a complication occurs if the complication threshold is exceeded for any organ volume. We used the average dose to a volume as a measure of radiation damage to that volume. Also, we used the power law to scale the average dose to various organ volumes to a whole-organ equivalent dose, and to identify the volume with the most harmful dose-size combination-the critical volume. We used a logistic distribution to calculate the probability that the patient will develop a complication, given the dose delivered to the critical volume. We used a maximum likelihood fit to estimate the model parameters for late-term rectal complications in a set of patients treated for prostate carcinoma with external photon beam radiotherapy (EBRT). Good correspondence was found between the experimental data and the model predictions.     

Influence of fluid-phase chemoattractants on polymorphonuclear leukocyte chemotaxic responsiveness to a surface-bound attractant

Polymoiphonuclear leukocytes (PMNLs) were allowed to migrate on slides with fixed yeast particles dotted about on the surface. Locomotion was quantified by counting the number of yeast particles in association with a PMNL, Addition of a complement source to yeast particles able to activate the complement system resulted in a chemotactic response even when fluid-phase attractants were removed prior to the measurement of PMNL chemotaxis, indicating that surface-bound attractants guided the PMNLs to the yeast particles. The presence of high concentrations of fluid-phase chemoattractants resulted in a reduced PMNL chemotactic response to the surface-bound gradient. From comparisons between the yeast-slide system and the locomotion-under-agarose assay, it could be concluded that PMNL chemotaxis in response to a surface-bound gradient is less influenced by factor-specific deactivation than the response to a fluid-phase attractant. The PMNL chemotactic response is reduced to both surface-bound and fluid-phase gradients as a result of a non-factorspecific deactivation.