The center-surround profile of the focus of attention arises from recurrent processing in visual cortex

We recently demonstrated with magnetoencephalographic recordings in human observers that the focus of attention in visual search has a spatial profile consisting of a center enhancement surrounded by a narrow zone of sensory attenuation. Here, we report new data from 2 experiments providing insights into the cortical processes that cause the surround attenuation. We show that surround suppression appears in search tasks that require spatial scrutiny, that is the precise binding of search-relevant features at the target's location but not in tasks that permit target discrimination without precise localization. Furthermore, we demonstrate that surround attenuation is linked with a stronger recurrent activity modulation in early visual cortex. Finally, we show that surround suppression appears with a delay (more than 175 ms) that is beyond the time course of the initial feedforward sweep of processing in the visual system. These observations together indicate that the suppressive surround is associated with recurrent processing and binding in the visual cortex.     

Parental rights and medical decisions

Most countries grant parents rebuttable legal rights to make treatment decisions on behalf of their young children, creating a presumption in favor of parental rights. This article identifies and provides a preliminary assessment of a perhaps surprising variety of arguments for the presumption in favor of this parental right. The arguments considered include those flowing from ideas that parents are motivated by their child's best interests; that they have privileged insight into their child's preferences and capacities; that parental support has clinical significance and may be contingent upon respect for the presumption; that parents and families typically bear the burden of treatment decisions; that parents' views often have a religious basis; that it would be improper to override parents' wishes other than in conditions of complete certainty; and that parents have 'natural authority' over their children. It is unlikely that this is an exhaustive list of the arguments that could be offered in favor of the presumption, and the treatment in the paper is brief. Nevertheless, it is hoped that enough is said to suggest that it is harder to defend the presumption than we might have supposed.     

Surgery offers no more than medical treatment in the management of transient ischaemic attack.

This paper debates the motion that 'Surgery offers no more than medical treatment in the management of transient ischaemic attack' (TIA). The arguments in support of this motion are that surgical treatment has a high morbidity and mortality, and that even the investigation of patients by angiography prior to surgery entails a risk of stroke; that TIA is a marker of generalised vascular disease, and that medical treatment can reduce the incidence of stroke after TIA. The counter arguments are that TIA is associated with an increased risk of stroke and this risk can be reduced by surgery; that recent surgical results show an acceptable complication rate, and that modern methods of investigation permit accurate non-invasive assessment of patients at risk of stroke.     

糖尿病患者骨代谢研究

本文测定７４例糖尿病住院患者的血Ｃａ、Ｐ、ＡＫＰ、ＢＧＰ、２４小时尿ＨＯＰ及腰椎２～４正位骨密度（ＢＭＤ）。结果（１）糖尿病患者血Ｃａ、Ｐ、ＡＫＰ与正常对照无显著差异，并且胰岛素依赖型糖尿病组（ＩＤＤＭ）与非胰岛素依赖型糖尿病组（ＮＩＤＤＭ）之间也无显著差异。（２）血ＢＧＰ变化，在ＩＤＤＭ组，２０～３９岁的女性和４０～５９岁的男性ＢＧＰ低于正常对照；ＮＩＤＤＭ组６０岁以上的女性患者ＢＧＰ也明显低于正常对照，而在２０～３９岁的男女患者ＢＧＰ却高于正常对照。（３）糖尿病患者尿ＨＯＰ高于正常对照，并且ＩＤＤＭ组与ＮＩＤＤＭ组比较也有显著差异。（４）骨质疏松发生率ＩＤＤＭ组高于ＮＩＤＤＭ组，而骨量减低发生率ＮＩＤＤＭ组高于ＩＤＤＭ组。初步探讨了糖尿病性骨质疏松的发病机制。     

Are screening programs in Barrett esophagus meaningful?

This review analyses whether the assumption is justified that endoscopic screening in patients with Barrett's syndrome facilitates early recognition of cancer and leads to prolongation of life. It is shown that no reliable data exist that would support the latter conclusion. Although there is scant information that some patients may benefit from close surveillance, it appears unlikely that an all too ambitious surveillance program will either be cost effective or acceptable for patients and/or endoscopy centers.     

Review of cellular mechanisms of tumor osteolysis

The cellular and biochemical mechanisms that direct the destruction of bone at sites of tumor osteolysis are unknown. To better understand the mechanisms through which tumors direct bone resorption, research has focused on developing in vivo and in vitro experimental models that are useful for studying this process. In vivo experimental systems have been developed that permit study of tumor osteolysis from human and murine tumors, and that permit the study of tumors that arise from (sarcoma) or can metastasize (breast cancer) to bone. Recent research has focused on three questions: (1) Are osteoclasts or tumor cells responsible for bone resorption during tumor osteolysis? (2) What are the cellular mechanisms that are responsible for bone resorption during tumor osteolysis, and (3) what are the tumor cell products that regulate the cellular mechanisms that are responsible for tumor osteolysis? It has been determined that osteoclasts are responsible for bone resorption at sites of tumor osteolysis by enhancing the binding of osteoclast to bone, by inducing osteoclastic bone resorption, and by stimulating osteoclast formation. Attempts to identify tumor cell products that regulate these cellular mechanisms are in progress, and findings suggest that production of macrophage colony stimulating factor may be required for tumor osteolysis to occur with some tumors.     

Nasal airway function as it relates to the timing of mid and lower facial osteotomies

It has been established in primate studies that mouth-breathing can affect lower facial development. We submit that mouth-breathing has a similar effect on human development--specifically, that chronic mouth-breathing during growth contributes to long-face syndrome. When reconstructive surgery is contemplated for this deformity, we believe that the sequence of surgical steps is important and that particular attention should be given to enhancing nasal respiration. The possibility that mouth-breathing is a factor in relapse following mandibular surgery is discussed.     

Relevance of basic research to clinical data: Good answers, wrong questions!

What conclusions can be derived from experimental data on human epilepsies? This review discusses these issues, notably concerning human temporal lobe epilepsies (TLEs) and infantile epilepsies, where important advances have been achieved in both theory and the comprehension of epileptogenic mechanisms. A wide spectrum of human and animal data converge to show that the naive network transforms to one that generates seizures spontaneously. Thus, in TLE, experimental and human data suggest that the inaugurating status generates a sequence of events that lead to the sprouting of fibers and the formation of novel excitatory synapses. This reactive plasticity constitutes a basis for the generation of novel seizures by the epileptic network. Similarly, in vitro studies indicate that in immature hippocampal formation, the propagation of high- but not low-frequency seizures can transform a naive network into one that generates further seizures, thereby, giving an indication as to the types of seizure that are epileptogenic. In conclusion, it is suggested that although animal data cannot mimic human seizures in all their complex and variable etiologies, it provides essential indications on the mechanisms that enable seizure generation.     

Benign prostatic hyperplasia and growth factors.

A great deal of work has been accomplished in the attempt to determine the cause of benign prostatic hyperplasia (BPH). Early work by morphologists suggests that BPH starts as a stromal disease and that the hyperplastic stroma secretes a substance that stimulates the growth of epithelial cells. The quantitative morphometric data also suggest that BPH is primarily a stromal disease. Experimental embryology data have shown that the basic fibroblast growth factor, bFGF, is involved in early embryogenesis and is the primary inducer of mesodermal tissue. Work in mouse embryos has shown that a powerful inducer for prostatic epithelial growth is elaborated by the urogenital mesenchyme. Both of these findings fit the hypothesis that stromal hyperplasia may be initiated by a growth factor and that a second growth factor stimulates epithelial growth. Work in our laboratory has established that bFGF is the primary growth factor present in human BPH. We have also found that bFGF is synthesized by prostate fibroblasts and bFGF may be in higher concentration in the periurethral tissues of BPH. At this time, no definite link between growth factors and hyperplastic growth of the prostate has been established. However, circumstantial evidence has lead us to formulate several hypothesis regarding the role of growth factors in BPH. Hopefully, these hypothesis will be of some assistance in guiding future work on growth factors and BPH.     

Aesthetic strategies for the aging Asian face

Aging that manifests in the Asian face is remarkably different, yet in many ways similar, to that of the white face. These dissimilarities and similarities are highlighted in this article along with overall strategies to approach the aging Asian face. This article focuses almost exclusively on the judgment and thinking that are required when approaching the Asian patient. More specifically, one issue that is covered is the cultural aspect that pertains to patient motivation and perspectives on cosmetic enhancement. The other equally important aspect that is addressed is elaboration of a new paradigm on what constitutes a youthful face, especially as that model relates to the Asian face.     

On the crossroad between tolerance and posttransplant lymphoma

The role of the Epstein-Barr virus in the development of post-transplant lymphomas is well established. However, not all lymphomas that arise in these patients contain Epstein-Barr virus, suggesting that other cofactors are involved in tumor pathogenesis. We propose that immunologic interactions that result from the introduction of immunocompetent donor cells during transplantation contribute to a lymphomagenic environment in the host. Murine models of lymphoma that arises following transfer of allogeneic hematopoietic cells are discussed and are related to the transplant setting. One contemporary viewpoint of transplantation immunology holds that interactions between the host and donor components of the immune system determine the ultimate degree of tolerance or reciprocal immunoreactivity (eg, rejection, graft-versus-host disease) within the transplant patient. We conclude that host-donor immunologic microchimerism may also be an over-looked factor in the development of posttransplant lymphomas.     

Pressure antagonism of barbiturate anesthesia.

The losses of righting reflex produced by various doses of phenobarbital in mice at 1 atm O2 versus 1 atm O2 plus 102 atm He were determined. The resulting dose-response curve at pressure gave an ED50 that was 64 per cent larger than the ED50 at 1 atm. This increment is essentially the same as that found for gaseous anesthetics under similar test conditions. The quantitative similarity of the results of pressure reversals of barbiturate and inhalational anesthetics suggests that the mechanisms or sites of action of these agents are similar. However, the dose-response curve at 103 atm was steeper than that at 1 atm. This raises an alternative possibility that anesthetics and pressure bear no mechanistic relationship to each other, but rather that pressure produces a generalized central nervous system stimulation that would antagonize any depressant effect.     

The Brain Trauma Foundation. The American Association of Neurological Surgeons. The Joint Section on Neurotrauma and Critical Care. Nutrition

Data show that starved head-injured patients lose sufficient nitrogen to reduce weight by 15% per week. Class II data show that 100-140% replacement of resting metabolism expenditure with 15-20% nitrogen calories reduces nitrogen loss. Data in non-head injured patients show that a 30% weight loss increased mortality rate. Class I data suggests that nonfeeding of head-injured patients by the first week increases mortality rate. The data strongly support feeding at least by the end of the first week. It has not been established that any method of feeding is better than another or that early feeding prior to 7 days improves outcome. Based on the level of nitrogen wasting documented in head-injured patients and the nitrogen sparing effect of feeding, it is a guideline that full nutritional replacement be instituted by day 7.     

Carbon dioxide laser studies of defects in articular cartilage.

With this further refinement, the author and colleagues hope to establish a reliable method of calculating the depth of penetration necessary to induce a deficit that will cause chondrogenesis in a predictable, reliable fashion. It is hoped that this will allow for consistent results so this technique may be used for the treatment of cartilage degeneration and certain arthritides. In addition, it is hoped that the fibrous cartilage regenerated from the experiments with animals will produce viable information that will lead to extensive human applications in the near future. The author also hopes that many joint destructive procedures such as arthroplasties and some implant procedures may be eliminated, and that this investigation will lead to advances that will eliminate much of the morbidity of arthritis.     

Reactivation of networks involved in preparatory states

We report an endogenous signal that has a widespread cortical distribution and is time-locked to the termination of a sustained state of task-readiness. In three event-related functional magnetic resonance imaging (fMRI) experiments, subjects saw an arrow cue that predicted either the direction of motion or the location of a subsequent test stimulus. A reactivation of the BOLD (blood oxygenation level-dependent) signal occurred at the termination of the state of readiness in occipital regions that were transiently activated by the cue and in frontal-parietal regions that maintained an attentional set over the trial. Moreover, a delayed activation occurred in prefrontal and temporo-parietal regions that did not initially respond to the cue and that have been implicated in re-orienting attention to novel sensory events. These latter regions may have generated control signals that ended the state of readiness in regions active during the cue period. These results indicate that terminating a state of readiness produces a widely distributed cortical signal and suggest that areas involved in a preparatory state may be maintained as a network which can be modulated as a whole.     

The microsurgical triple clamp: a technique for microvascular grafting of short interposition grafts

The microsurgical triple clamp has been developed for use when grafting arteries and veins. Advantages are that the grafting technique can be performed by one person, that the clamp anchors the graft so that quick yet accurate anastomoses can be performed, and that visualization of the back wall is possible throughout the anastomosis.     

Intratumor heterogeneity,variability and plasticity: questioning the current concepts in classification and treatment of hepatocellular carcinoma

In the classical view, the formation of a primary tumor is the consequence of a mutational event that first affects a single cell that subsequently passes through a multitude of consecutive hyperplastic and dysplastic stages. At the end of this pathogenetic sequence a cell arises that is potentially able to expanse infinitely having capacity to form a homogenous tumor mass. In contrary to this clonal expansion concept, the majority of primary human tumors display already a startling heterogeneity that can be reflected in different morphological features, physiological activities, and genetic diversity. In the past it was speculated that this cancer cell plasticity within a tumor is the result of an adaptive process that is induced by specific inhibiting therapies. In regard to the formation of hepatocellular carcinoma (HCC) this dogma was once challenged in a recent study that analysed tumor areas that were taken from HCC patients without medical pretreatment. Most of the analyzed samples showed highly significant intratumor heterogeneity. This affected morphological attributes, immunohistochemical stainability of five tumor-associated markers [α-fetoprotein (AFP), EpCAM, CK7, CD44 and glutamine synthetase], and integrity of genes (β-catenin and p53) that are critically involved in the pathogenesis of HCC. Altogether, this study showed that intratumor heterogeneity is a frequent finding in HCC that may contribute to treatment failure and drug resistance in HCC patients.     

Pathophysiology of acne

Acne is a disease that develops in pilosebaceous follicles. Acne was long considered was an infectious disease related to Propionibac-terium acnes, but studies show that the production of inflammatory substances in situ was much more important to the action of this bacterium than was simple infection. It was once thought that only the androgens could stimulate the seba-ceous gland, but today we know that neuromediators can also stimulate sebum production. This finding provides physiological support to the clinical observation that stress can induce acne.