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1.
Herpes zoster, an acute specific viral infection, occurs more commonly than is generally supposed. It should be differentiated from other diseases involving the ear and skin; it must be considered as a possible etiologic agent in some palsies of the facial, glossopharyngeal or vagal nerves.The type of cephalic herpes zoster should be carefully differentiated; cases involving the “geniculate zone” may be other than “Ramsay Hunt''s syndrome.” This syndrome is now defined as a herpes zoster eruption of the external ear at the “geniculate zone” with involvement of the seventh or seventh and eighth nerves.The “topognostic” method is the best for determining the level at which the facial nerve has been affected.It is questioned whether there is a single outstanding therapeutic agent for this disease. Cortisone had no apparent therapeutic effect in a case reported herein.  相似文献   

2.
Enzymes are well known for their catalytic abilities, some even reaching “catalytic perfection” in the sense that the reaction they catalyze has reached the physical bound of the diffusion rate. However, our growing understanding of enzyme superfamilies has revealed that only some share a catalytic chemistry while others share a substrate‐handle binding motif, for example, for a particular phosphate group. This suggests that some families emerged through a “substrate‐handle‐binding‐first” mechanism (“binding‐first” for brevity) instead of “chemistry‐first” and we are, therefore, left to wonder what the role of non‐catalytic binders might have been during enzyme evolution. In the last of their eight seminal, back‐to‐back articles from 1976, John Albery and Jeremy Knowles addressed the question of enzyme evolution by arguing that the simplest mode of enzyme evolution is what they defined as “uniform binding” (parallel stabilization of all enzyme‐bound states to the same degree). Indeed, we show that a uniform‐binding proto‐catalyst can accelerate a reaction, but only when catalysis is already present, that is, when the transition state is already stabilized to some degree. Thus, we sought an alternative explanation for the cases where substrate‐handle‐binding preceded any involvement of a catalyst. We find that evolutionary starting points that exhibit negative catalysis can redirect the reaction''s course to a preferred product without need for rate acceleration or product release; that is, if they do not stabilize, or even destabilize, the transition state corresponding to an undesired product. Such a mechanism might explain the emergence of “binding‐first” enzyme families like the aldolase superfamily.  相似文献   

3.
The evolution of the faculty of language largely remains an enigma. In this essay, we ask why. Language''s evolutionary analysis is complicated because it has no equivalent in any nonhuman species. There is also no consensus regarding the essential nature of the language “phenotype.” According to the “Strong Minimalist Thesis,” the key distinguishing feature of language (and what evolutionary theory must explain) is hierarchical syntactic structure. The faculty of language is likely to have emerged quite recently in evolutionary terms, some 70,000–100,000 years ago, and does not seem to have undergone modification since then, though individual languages do of course change over time, operating within this basic framework. The recent emergence of language and its stability are both consistent with the Strong Minimalist Thesis, which has at its core a single repeatable operation that takes exactly two syntactic elements a and b and assembles them to form the set {a, b}.It is uncontroversial that language has evolved, just like any other trait of living organisms. That is, once—not so long ago in evolutionary terms—there was no language at all, and now there is, at least in Homo sapiens. There is considerably less agreement as to how language evolved. There are a number of reasons for this lack of agreement. First, “language” is not always clearly defined, and this lack of clarity regarding the language phenotype leads to a corresponding lack of clarity regarding its evolutionary origins. Second, there is often confusion as to the nature of the evolutionary process and what it can tell us about the mechanisms of language. Here we argue that the basic principle that underlies language''s hierarchical syntactic structure is consistent with a relatively recent evolutionary emergence.  相似文献   

4.
There is no perfect recipe to balance work and life in academic research. Everyone has to find their own optimal balance to derive fulfilment from life and work. Subject Categories: S&S: Careers & Training

A few years ago, a colleague came into my office, looking a little irate, and said, “I just interviewed a prospective student, and the first question was, ‘how is work‐life balance here?’”. Said colleague then explained how this question was one of his triggers. Actually, this sentiment isn''t unusual among many PIs. And, yet, asking about one''s expected workload is a fair question. While some applicants are actually coached to ask it at interviews, I think that many younger scientists have genuine concerns about whether or not they will have enough time away from the bench in order to have a life outside of work.In a nutshell, I believe there is no one‐size‐fits‐all definition of work–life balance (WLB). I also think WLB takes different forms depending on one''s career stage. As a new graduate student, I didn''t exactly burn the midnight oil; it took me a couple of years to get my bench groove on, but once I did, I worked a lot and hard. I also worked on weekends and holidays, because I wanted answers to the questions I had, whether it was the outcome of a bacterial transformation or the result from a big animal experiment. As a post‐doc, I worked similarly hard although I may have actually spent fewer hours at the bench because I just got more efficient and because I read a lot at home and on the six train. But I also knew that I had to do as much as I could to get a job in NYC where my husband was already a faculty member. The pressure was high, and the stress was intense. If you ask people who knew me at the time, they can confirm I was also about 30 pounds lighter than I am now (for what it''s worth, I was far from emaciated!).As an assistant professor, I still worked a lot at the bench in addition to training students and writing grant applications (it took me three‐plus years and many tears to get my first grant). As science started to progress, work got even busier, but in a good way. By no means did I necessarily work harder than those around me—in fact, I know I could have worked even more. And I’m not going to lie, there can be a lot of guilt associated with not working as much as your neighbor.My example is only one of millions, and there is no general manual on how to handle WLB. Everyone has their own optimal balance they have to figure out. People with children or other dependents are particularly challenged; as someone without kids, I cannot even fathom how tough it must be. Even with some institutions providing child care or for those lucky enough to have family take care of children, juggling home life with “lab life” can create exceptional levels of stress. What I have observed over the years is that trainees and colleagues with children become ridiculously efficient; they are truly remarkable. One of my most accomplished trainees had two children, while she was a post‐doc and she is a force to be reckoned with—although no longer in my laboratory, she still is a tour de force at work, no less with child number three just delivered! I think recruiters should view candidates with families as well—if not better—equipped to multi‐task and get the job done.There are so many paths one can take in life, and there is no single, “correct” choice. If I had to define WLB, I would say it is whatever one needs to do in order to get the work done to one''s satisfaction. For some people, putting in long days and nights might be what is needed. Does someone who puts in more hours necessarily do better than one who doesn''t, or does a childless scientist produce more results than one with kids? Absolutely not. People also have different goals in life: Some are literally “wedded” to their work, while others put much more emphasis on spending time with their families and see their children grow up. Importantly, these goals are not set in stone and can fluctuate throughout one''s life. Someone recently said to me that there can be periods of intense vertical growth where “balance” is not called for, and other times in life where it is important and needed. I believe this sentiment eloquently sums up most of our lives.Now that I''m a graying, privileged professor, I have started to prioritize other areas of life, in particular, my health. I go running regularly (well, maybe jog very slowly), which takes a lot of time but it is important for me to stay healthy. Pre‐pandemic, I made plans to visit more people in person as life is too short not to see family and friends. In many ways, having acquired the skills to work more efficiently after many years in the laboratory and office, along with giving myself more time for my health, has freed up my mind to think of science differently, perhaps more creatively. It seems no matter how much I think I’m tipping the balance toward life, work still creeps in, and that’s perfectly OK. At the end of the day, my work is my life, gladly, so I no longer worry about how much I work, nor do I worry about how much time I spend away from it. If you, too, accomplish your goals and derive fulfillment from your work and your life, neither should you.  相似文献   

5.
《CMAJ》1987,136(4):424A-424B
The CMA believes that there are conditions of ill health and inevitable death for which a “no resuscitation” order, signed by the attending physician, is appropriate and ethically acceptable. The association encourages physicians who are faced with the decision of writing a “no resuscitation” or “do not resuscitate” order to consider the clinical criteria and procedural guidelines in the Joint Statement on Terminal Illness. This protocol is intended as a basic, national guideline for those involved in the care of the terminally ill. Individual institutions may wish to develop their own directives as an adjunct to the national statement.  相似文献   

6.
7.
Organic acids derived from engineered microbes can replace fossil-derived chemicals in many applications. Fungal hosts are preferred for organic acid production because they tolerate lignocellulosic hydrolysates and low pH, allowing economic production and recovery of the free acid. However, cell death caused by cytosolic acidification constrains productivity. Cytosolic acidification affects cells asynchronously, suggesting that there is an underlying cell-to-cell heterogeneity in acid productivity and/or in resistance to toxicity. We used fluorescence microscopy to investigate the relationship between enzyme concentration, cytosolic pH, and viability at the single-cell level in Saccharomyces cerevisiae engineered to synthesize xylonic acid. We found that cultures producing xylonic acid accumulate cells with cytosolic pH below 5 (referred to here as “acidified”). Using live-cell time courses, we found that the probability of acidification was related to the initial levels of xylose dehydrogenase and sharply increased from 0.2 to 0.8 with just a 60% increase in enzyme abundance (Hill coefficient, >6). This “switch-like” relationship likely results from an enzyme level threshold above which the produced acid overwhelms the cell''s pH buffering capacity. Consistent with this hypothesis, we showed that expression of xylose dehydrogenase from a chromosomal locus yields ∼20 times fewer acidified cells and ∼2-fold more xylonic acid relative to expression of the enzyme from a plasmid with variable copy number. These results suggest that strategies that further reduce cell-to-cell heterogeneity in enzyme levels could result in additional gains in xylonic acid productivity. Our results demonstrate a generalizable approach that takes advantage of the cell-to-cell variation of a clonal population to uncover causal relationships in the toxicity of engineered pathways.  相似文献   

8.
If a chemical reaction is constrained to occur within an asymmetric structure, e.g. by the presence of bound or otherwise trapped enzyme, coupling of the reaction to the flow of one or more solutes, or to the flow of electric current, becomes possible. Such systems can serve as models in which transport is “driven” by chemical reaction. In this respect the processes involved are analogous to active transport, though the molecular mechanisms may be quite different from those in nature. A simple arrangement of this kind has been studied: a composite membrane consisting of two ion exchange membranes of opposite fixed charge, separated by an intermediate layer of solution containing papain. An uncharged substrate of low molecular weight acts as “fuel” for the system, N-acetyl-L-glutamic acid diamide. This material (not previously described) hydrolyzes in the presence of papain to ammonium N-acetyl-L-glutamine. The composite membrane gives rise to an electromotive force, ultimately reaching a stationary state, when clamped between two identical solutions in which the affinity of the reaction has been fixed. Onsager''s reciprocity relation has not hitherto been tested in a case of coupling between chemical reaction and a vectorial flow (here electric current); its validity for this system, in which stationary-state coupling occurs, was established over the experimental range of affinities (up to 3 kcal/mole).  相似文献   

9.
A dissociation between visual awareness and visual discrimination is referred to as “blindsight”. Blindsight results from loss of function of the primary visual cortex (V1) which can occur due to cerebrovascular accidents (i.e. stroke-related lesions). There are also numerous reports of similar, though reversible, effects on vision induced by transcranial Magnetic Stimulation (TMS) to early visual cortex. These effects point to V1 as the “gate” of visual awareness and have strong implications for understanding the neurological underpinnings of consciousness. It has been argued that evidence for the dissociation between awareness of, and responses to, visual stimuli can be a measurement artifact of the use of a high response criterion under yes-no measures of visual awareness when compared with the criterion free forced-choice responses. This difference between yes-no and forced-choice measures suggests that evidence for a dissociation may actually be normal near-threshold conscious vision. Here we describe three experiments that tested visual performance in normal subjects when their visual awareness was suppressed by applying TMS to the occipital pole. The nature of subjects’ performance whilst undergoing occipital TMS was then verified by use of a psychophysical measure (d'') that is independent of response criteria. This showed that there was no genuine dissociation in visual sensitivity measured by yes-no and forced-choice responses. These results highlight that evidence for visual sensitivity in the absence of awareness must be analysed using a bias-free psychophysical measure, such as d'', In order to confirm whether or not visual performance is truly unconscious.  相似文献   

10.
Retrolental fibroplasia is today the principal cause of blindness in children of preschool age, exceeding all other causes combined. The disease occurs in infants of low weight at birth, commonly those born prematurely. The incidence of the disease is rising at an alarming rate. Vitamin E deficiency, corticotropin (ACTH) deficiency, the use of cow''s milk in place of mother''s milk, and improper oxygenation have been suggested as etiologic factors but the cause remains a mystery. Often the incidence is high in institutions in which maximal care is given premature infants.Clinically, the disease advances through an “active” phase during which regression is possible, and a “subsiding” or “cicatricial” phase which terminates with the formation of a disorganized opaque mass behind the lens. The earliest manifestations are noted in the fundi. Hemorrhages, neovascularization, transudation commencing in the periphery, and retinal separation contribute to the formation of the characteristic retrolental membrane. The diagnosis may be made when the retrolental membrane is observed in the eye of an infant whose weight at birth was low. Differential diagnosis is required occasionally.Thus far, no form of therapy has prevented or reversed the pathologic changes successfully. Use of vitamin E, corticotropin and mother''s milk has not influenced the incidence of the disease. Avoidance of premature delivery if possible is indicated.  相似文献   

11.
Methoxyflurane and nitrous oxide have been compared as obstetric analgesics. The inhaled concentrations of these agents, given continuously, were adjusted by an anaesthetist to maintain each patient at the optimum state between reaction to pain and consciousness. Assessments were made continuously.Though the anaesthetist''s assessment showed no difference between the mean results, a greater proportion of the methoxyflurane patients were “satisfactory” for 90–100% of the time than of the nitrous oxide patients, particularly in regard to objective pain relief. The midwives'' opinion of those who had “complete” pain relief supported this. Nausea was significantly less among methoxyflurane patients, and vomiting during labour occurred only in patients who had nitrous oxide. It is concluded that nitrous oxide and methoxyflurane given in a continuously adjusted concentration are almost equally effective as obstetric analgesics, though there are certain features which favour methoxyflurane.  相似文献   

12.
Alan M. Mann  Ellen M. Gold 《CMAJ》1966,95(26):1359-1363
Litigation for personal injury following accidental trauma is an expensive and confused process involving three protagonists: patient, doctor and lawyer. Although post-traumatic conditions can be elaborately classified, the intrinsic validity of such classifications is often questionable. Current methods of evaluating psychological sequelae of accidental injury are inaccurate and unsatisfactory, partly because of the protagonists'' conceptual, motivational and semantic differences. In addition, there is no really satisfactory method of (a) determining and quantifying minor but significant degrees of brain damage, (b) distinguishing these from “post-traumatic neurosis”, or (c) determining the relationship between the trauma and subsequent disturbance of function. Increasingly “expert” advice is solicited but owing to the nature of the data and conditions of examination, such advice does little to clarify the underlying problems. Furthermore, doctors are often unable to communicate effectively to the judiciary just how the trauma has affected the patient. Even though certain suggestions for improvement are advanced, the need for comprehensive, longitudinal research is inescapable.  相似文献   

13.
“Hidden alcoholics”—those who drink surreptitiously to keep their addiction secret—far out-number the overt habitues of skid rows. The former rather than the latter should be considered “typical” alcoholics. Even though they have severe problems, they maintain fairly good employment stability and stability in marriage. Yet they steadily deteriorate.Often “hidden” alcoholics go to physicians because of symptoms referable to alcoholism but contrive to conceal their addiction and so make diagnosis difficult. Hence, physicians observing certain kinds of symptoms that cannot be attributed to a readily observable or demonstrable pathologic change should make searching inquiry as to the patient''s drinking habits. For not until the proper diagnosis is made in such cases can there be hope of effective treatment.  相似文献   

14.
15.
Many years of training are required to obtain a job as an academic scientist. Is this investment of time and effort worthwhile? My answer is a resounding “yes.” Academic scientists enjoy tremendous freedom in choosing their research and career path, experience unusual camaraderie in their lab, school, and international community, and can contribute to and enjoy being part of this historical era of biological discovery. In this essay, I further elaborate by listing my top ten reasons why an academic job is a desirable career for young people who are interested in the life sciences.Students are attracted to careers in academic science because of their interest in the subject rather than for financial reward. But then they hear messages that make them think twice about this career choice. It is difficult to find a job: “Hear about Joe? Three publications as a postdoc and still no job offers.” The NIH pay line is low: “Poor Patricia, she is now on her third submission of her first NIH grant.” Publishing is painful: “Felix''s grad school thesis work has been rejected by three journals!” Academic jobs are demanding: “Cathy has spent her last three weekends writing grants rather than being with her family.”Such scenarios do take place, but if you think that this is what a career in academic science is about, then you need to hear the other side of the story. And this is the purpose of this article—a chance to reflect on the many good things about the academic profession. In the classic movie It''s a Wonderful Life, George Bailey is at the point of despair but regains his confidence through the wisdom and perspective of a guardian angel, Clarence. Doubt and setbacks also are bound to happen in science (as is true of other careers), but pessimism should not rule the day. It is a great profession and there are many happy endings. I would like to share my top ten reasons of why being an academic professor is a “wonderful life,” one that bright and motivated young people should continue to aspire to pursue.  相似文献   

16.
M. A. Baltzan 《CMAJ》1972,106(3):249-256
The volume of medical services delivered within hospital emergency departments in the City of Saskatoon is increasing rapidly. These probably are not “new” medical services but rather represent a transfer of “old” services to the emergency departments from other sites where they were previously rendered. The visit to the emergency department is initiated more often by the patient than the doctor and once there the patient is treated in a relatively short period of time. The illnesses so managed do not have a diagnostic, therapeutic or prognostic uniformity but rather are characterized by their acute and totally unexpected onset. This acute and non-programmable nature of the illness makes it difficult to deliver the service in a physician''s office where the appointment system prevails and efficiently deals with the great majority of his patients. Data to determine whether or not this is a desirable development have not yet been obtained but it is clear that in its present usage the emergency department must be thought of as a facility which not only provides exceptional diagnostic and therapeutic equipment but as one which also provides a treatment facility without prior appointment available at any hour of the day or night.  相似文献   

17.
The safety of chemicals, drugs, novel foods and genetically modified crops is often tested using repeat-dose sub-acute toxicity tests in rats or mice. It is important to avoid misinterpretations of the results as these tests are used to help determine safe exposure levels in humans. Treated and control groups are compared for a range of haematological, biochemical and other biomarkers which may indicate tissue damage or other adverse effects. However, the statistical analysis and presentation of such data poses problems due to the large number of statistical tests which are involved. Often, it is not clear whether a “statistically significant” effect is real or a false positive (type I error) due to sampling variation. The author''s conclusions appear to be reached somewhat subjectively by the pattern of statistical significances, discounting those which they judge to be type I errors and ignoring any biomarker where the p-value is greater than p = 0.05. However, by using standardised effect sizes (SESs) a range of graphical methods and an over-all assessment of the mean absolute response can be made. The approach is an extension, not a replacement of existing methods. It is intended to assist toxicologists and regulators in the interpretation of the results. Here, the SES analysis has been applied to data from nine published sub-acute toxicity tests in order to compare the findings with those of the author''s. Line plots, box plots and bar plots show the pattern of response. Dose-response relationships are easily seen. A “bootstrap” test compares the mean absolute differences across dose groups. In four out of seven papers where the no observed adverse effect level (NOAEL) was estimated by the authors, it was set too high according to the bootstrap test, suggesting that possible toxicity is under-estimated.  相似文献   

18.
Enzymatic catalysis of biochemical reactions is essential to all living systems. The “lock and key” and “induced fit” models were early contributions to our understanding of the mechanisms involved in the reaction between an enzyme and its substrate. However, whether a given substrate-induced conformation is rigid or remains flexible has not yet been determined. By measuring the enzyme activity and intrinsic fluorescence of a nonspecific Eisenia fetida protease-I with different chromogenic substrates, we show that in subsequent reactions of protease with substrates, both the “lock and key” and “induced fit” mechanisms are used depending on the degree of conformational change required. Chromozym-Th- or chromosym-Ch-induced protease conformations were unable to bind chromozym-U. The chromosym-U-induced protease conformation remained flexible and could be further induced by chromozym-Th and chromozym-Ch. When low concentrations of guanidine HCl were used to disturb the conformation of the enzyme, only small changes in intrinsic fluorescence of the chromozym-Th-induced protease were detected, in contrast to the native enzyme whose intrinsic fluorescence markedly increased. This indicates that the substrate-induced enzyme was relatively rigid compared with the native protease. Utilizing a lock and key mechanism for secondary substrate reactions may have adaptive value in that it facilitates high efficiency in enzymatic reactions.  相似文献   

19.
Deep cuts in greenhouse gas emissions are required to mitigate climate change. However, there is low willingness amongst the public to prioritise climate policies for reducing emissions. Here we show that the extent to which Australians are prepared to reduce their country''s CO2 emissions is greater when the costs to future national income are framed as a “foregone-gain”—incomes rise in the future but not by as much as in the absence of emission cuts—rather than as a “loss”—incomes decrease relative to the baseline expected future levels (Studies 1 & 2). The provision of a normative message identifying Australia as one of the world''s largest CO2 emitters did not increase the amount by which individuals were prepared to reduce emissions (Study 1), whereas a normative message revealing the emission policy preferences of other Australians did (Study 2). The results suggest that framing the costs of reducing emissions as a smaller increase in future income and communicating normative information about others'' emission policy preferences are effective methods for leveraging public support for emission cuts.  相似文献   

20.

Background

The evidence for culture in non-human animals has been growing incrementally over the past two decades. However, the ability for cumulative cultural evolution, with successive generations building on earlier achievements, in non-human animals remains debated. Faithful social learning of incremental improvements in technique is considered to be a defining feature of human culture, differentiating human from non-human cultures. This study presents the first experimental evidence for chimpanzees'' social transmission of a more efficient tool-use technique invented by a conspecific group member.

Methodology/Principal Findings

The chimpanzees were provided with a straw-tube, and spontaneously demonstrated two different techniques in obtaining juice through a small hole: “dipping” and “straw-sucking”. Both the “dipping” and “straw-sucking” techniques depended on the use of the same tool (straw-tube) for the same target (juice) accessible from exactly the same location (small hole 1 cm in diameter). Therefore the difference between “dipping” and “straw-sucking” was only in “technique”. Although the two techniques differed significantly in their efficiency, their cognitive and perceptuo-motor complexity were comparable. All five chimpanzees who initially performed the “dipping” technique switched to using the more efficient “straw-sucking” technique upon observing a conspecific or human demonstrate the more proficient alternate “straw-sucking” technique.

Conclusions/Significance

The social learning mechanism involved here was clearly not local or stimulus enhancement, but imitation or emulation of a tool-use technique. When there is no biologically relevant difference in cognitive or perceptuo-motor complexity between two techniques, and when chimpanzees are dissatisfied with their own technique, chimpanzees may socially learn an improved technique upon close observation of a proficient demonstrator. This study provides important insights into the cognitive basis for cumulative culture in chimpanzees, and also suggests possible conditions in which cumulative cultural evolution could arise even in non-human animals.  相似文献   

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