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1.
The predator-prey relationship between California ground squirrels (Spermophilus beecheyi) and northern Pacific rattlesnakes (Crotalus viridis) is a useful system for exploring conflict and assessment. Rattlesnakes are major predators of ground squirrel pups, but pose a less significant threat to adult squirrels. Adults approach, harass, and even attack rattlesnakes in defense of their pups. Two factors that may influence risk to both squirrel and snake during encounters are the size and body temperature of the rattlesnake. We used high-speed video to analyze the strikes of rattlesnakes of various sizes tested at different body temperatures. Results indicate that warmer snakes are more dangerous because they strike with higher velocity, greater accuracy, and less hesitation. Similarly, larger snakes are more dangerous because they can strike farther and at higher speeds, and keep their fangs embedded longer. Thus, ground squirrels would benefit from extracting information about a rattlesnake's size and temperature. The converse of our results is that cooler, smaller rattlesnakes may be more vulnerable. These snakes could mitigate their risk by avoiding dangerous adversaries and minimizing cues that divulge their weaknesses. Such tactics might explain the active probing that squirrels direct at rattlesnakes, which may function to overcome a snake's resistance to disclosing its vulnerability.  相似文献   

2.
Prey animals are often confronted with situations that differ in predation risk. According to the risk allocation hypothesis, prey animals should adaptively allocate antipredator behaviour in accordance with the magnitude and frequency of those risk situations. According to the first prediction prey animals should increase foraging in the safe situations and decrease foraging in the dangerous situations as these situations become relatively more dangerous. The second prediction is that with increased time spent in the dangerous situations, progressively more foraging effort is shown in both the dangerous and safe situations, especially in the safer ones. Prey animals may, however, show maladaptive behaviour due to behavioural correlations across risk situations. Here we test for the first time both predictions generated by the risk allocation hypothesis while considering behavioural correlations. We reared larvae of the damselfly Ischnura elegans, from the egg stage, under five rearing risk conditions: (i) in isolation, (ii) in the presence of conspecific larvae, (iii) in the presence of one fish, (iv) in the presence of two fish, and (v) in the presence of two fish for 50% of the time. For each rearing risk condition, we scored their behaviour in the absence and in the presence of fish. In accordance with the first prediction, in the absence of a predator, larvae reared under increasing risk conditions increased their level of foraging. In accordance with the second prediction, in the absence of a predator, larvae that were more frequently exposed to fish during rearing, increased foraging. However, opposite to the predictions from the risk allocation hypothesis, foraging increased both with increasing rearing risk, and with increased predator exposure frequency. The observed positive behavioural correlation of foraging activity across test situations with and without fish, may generate the combination of adaptive patterns in the absence of fish and the maladaptive patterns in the presence of fish. Former studies of the risk allocation hypothesis also found, at best, mixed support, and we hypothesize that behavioural correlations across risk situations, if present, will likely cause partial deviations from model predictions.  相似文献   

3.
Both radiotherapy and chemotherapy for cancer are capable of causing nausea and vomiting. With both treatment modalities, the nausea and vomiting is thought to be a second-order process rather than being due to direct stimulation of neuromechanisms that control vomiting. Both a peripheral (gastrointestinal tract) and central (chemoreceptor trigger zone) effect may be operating with both radiotherapy- and chemotherapy-induced vomiting. With radiotherapy, gastrointestinal toxicity is affected by the type of radiation, radiation dose and field size, fractionation schedule, individual patient factors, and the part of the patient that is radiated. Many different factors also influence the frequency and severity of nausea and vomiting following chemotherapy. With both radiotherapy and chemotherapy, the frequency and severity of nausea and vomiting is probably mediated by a reduction in breakdown of various neurotransmitters. It is presumed that as the levels of neurotransmitters increase, nausea and vomiting develop. Antagonists of these neurotransmitters may afford some antiemetic protection. Nausea and vomiting may be so severe in patients with cancer that they may refuse potentially curative therapy because of it. Anticipatory nausea and vomiting may develop in patients who have become quite sick after receiving treatment. Exposure to stimuli associated with the emetogenic agent is then sufficient to trigger nausea and vomiting. Standard antiemetics do not help anticipatory nausea and vomiting, although behavioural training may. A variety of different drugs have proven useful as antiemetics, including dopamine antagonists such as phenothiazines, metoclopramide, corticosteroids (dexamethasone and methylprednisolone), cannabinoids, and benzodiazapines. Antihistamines and anticholinergics are of value in some situations. New serotonin antagonists appear to be very promising and are currently undergoing clinical studies. Multiagent antiemetic regimens appear to be more effective than single agent regimens in some situations.  相似文献   

4.
S P Pietak  S J Teasdale 《CMAJ》1979,121(7):922-8
Hemodynamic monitoring and care of the patient at high risk for anesthesia require a careful and systematic approach. During preoperative evaluation the patient at increased risk must be identified and correctable problems must be solved. The patient''s current medications must be reviewed because they may influence the choice of anesthetic approach and may alter the physiologic response to the stresses commonly associated with anesthesia. In addition to conventional clinical and electrocardiographic monitoring, perioperative hemodynamic monitoring may be desirable for patients at special risk, who are likely to have significant associated medical problems or to undergo complicated surgical procedures. No ideal induction agent exists, and hypotension secondary to peripheral vasodilation or myocardial depression, or both, is a potential problem. Patients with an inordinately high risk may benefit from mechanical circulatory assistance prior to induction of anesthesia. Attention to oxygenation, blood volume replacement and the prevention of hypertensive episodes are particularly important during anesthesia so that optimal cardiac performance is ensured and ischemia avoided. The stresses during emergence from anesthesia contribute to lability of the cardiovascular status and hypoxemia. The period of risk does not conclude with immediate recovery from anesthesia but extends through the postoperative phase. Careful monitoring and attention to the control of pain, prevention of hypotension and hypertension, adequate oxygenation, early mobilization and resumption of the administration of cardiac medications are important factors in a successful outcome.  相似文献   

5.
The main medical use of vaccines is to induce a state of immunity in healthy individuals to protect them from deadly or dangerous diseases. In the field of cancer immunology, however, vaccines are being used in patients as therapy, often with a very poor success rate against advanced disease. This paper reviews recent preclinical evidence in favor of the prophylactic use of immunological approaches to cancer. Successful attempts at immunological cancer prevention in HER-2/neu transgenic mice are described as an example. The specific properties of the HER-2/neu gene product as a tumor antigen, and the nature of the immune responses induced by effective preventive treatments are reviewed. Although the very high rate of mammary carcinoma prevention in mice has generated enthusiasm, it should not be forgotten that such treatments, when administered to healthy humans at risk of cancer, may carry the risk of inducing autoimmunity. These issues can be addressed in preclinical studies in appropriate animal models.  相似文献   

6.
Postoperative nausea and vomiting frequently complicate outpatient anesthesia and surgery. The duration of treatment for this complication must occasionally extend beyond discharge from the hospital. In this study, we evaluated the commonly used anti-emetic promethazine for its efficacy in the post-discharge period. Adult outpatient surgical patients who had excessive postoperative nausea and vomiting in the recovery room, or who were at risk for postoperative nausea and vomiting following discharge were given two promethazine suppositories (25 mg) for home use. All patients were contacted by our recovery room nurses on the first business day after their surgery and questioned as to their use of the suppositories and, if used, their efficacy. We found that 55 percent of patients given promethazine suppositories for home use had nausea and vomiting in the post-discharge period. Of the patients given promethazine, 89 percent used the suppositories. All of these patients reported improvement in their symptoms following use of the suppositories. None reported adverse effects from the promethazine suppositories. In conclusion, we found promethazine suppositories to be an inexpensive and efficacious treatment for nausea and vomiting in adult outpatient surgical patients following discharge from the hospital. Side-effects were minimal, and our patients voiced no complaints about this mode of therapy. We recommend this therapy for treatment of nausea and vomiting after hospital discharge following adult outpatient surgery.  相似文献   

7.
Due to early diagnosis and appropriate paediatric treatment, internists and endocrinologists are now caring for an increasing number of adult patients with congenital adrenal hyperplasia (CAH). Problems that may be encountered in adult males with CAH are the continuing risk of developing an adrenal crisis and impaired gonadal function due to suppression of the hypothalamic-gonadal axis. Fertility may be further compromised by testicular adrenal rest tumours. Available data suggest that the reversal of infertility is more difficult once testicular nodules have developed. Similar to female CAH patients, male patients may develop adrenal tumours due to inadequate adrenocorticotropic hormone suppression. We therefore recommend continuous treatment of male CAH patients with careful monitoring of clinical and hormonal parameters in order to avoid overtreatment.  相似文献   

8.

Background

Dengue causes 50 million infections per year, posing a large disease and economic burden in tropical and subtropical regions. Only a proportion of dengue cases require hospitalization, and predictive tools to triage dengue patients at greater risk of complications may optimize usage of limited healthcare resources. For severe dengue (SD), proposed by the World Health Organization (WHO) 2009 dengue guidelines, predictive tools are lacking.

Methods

We undertook a retrospective study of adult dengue patients in Tan Tock Seng Hospital, Singapore, from 2006 to 2008. Demographic, clinical and laboratory variables at presentation from dengue polymerase chain reaction-positive and serology-positive patients were used to predict the development of SD after hospitalization using generalized linear models (GLMs).

Principal findings

Predictive tools compatible with well-resourced and resource-limited settings – not requiring laboratory measurements – performed acceptably with optimism-corrected specificities of 29% and 27% respectively for 90% sensitivity. Higher risk of severe dengue (SD) was associated with female gender, lower than normal hematocrit level, abdominal distension, vomiting and fever on admission. Lower risk of SD was associated with more years of age (in a cohort with an interquartile range of 27–47 years of age), leucopenia and fever duration on admission. Among the warning signs proposed by WHO 2009, we found support for abdominal pain or tenderness and vomiting as predictors of combined forms of SD.

Conclusions

The application of these predictive tools in the clinical setting may reduce unnecessary admissions by 19% allowing the allocation of scarce public health resources to patients according to the severity of outcomes.  相似文献   

9.
在过去的几十年里,随着各种手术技术的不断提高和完善,已使外科手术的死亡率大幅降低,这使医生的注意力逐渐转向手术后的并发症和患者的满意程度上,如手术后恶心呕吐。恶心呕吐是术后严重的并发症之一,尽管术后恶心呕吐(Postoperativenausea and vomiting,PONV)是非致命性的并发症,但是PONV可导致严重的后果,并且增加了医疗费用,极大的影响了患者的满意程度。PONV高发率一直困扰着临床医生和患者。所以,探讨其发生及其风险因素是十分必要的。但是,术后恶心呕吐的病理生理学机制还不是十分清楚,本文总结了目前关于术后恶心呕吐发生机制的一些观点以及术后恶心呕吐的风险因素。虽然以往大量的文献报道了如何预防和治疗术后恶心呕吐,但迄今为止,5-HT3受体拮抗剂仍然是临床上使用的最主要的止吐药。目前,一些新药物,如NK-1受体拮抗剂、更加长效的5-HT3受体拮抗剂以及对于PONV高风险的病人实行的多模式管理和新技术的应用,正变得越来越突出。本文综述了现今手术后恶心呕吐的防治方法的最新进展。  相似文献   

10.
目的:探讨小儿病毒性腹泻的临床预后及危险因素。方法:纳入病例是2018年1月至2019年12月本院收治的200例小儿病毒性腹泻患者,回顾性分析其临床资料,分析小儿病毒性腹泻的临床特点。根据疾病痊愈情况分组,将128例痊愈患者作为实验组,72例未痊愈患者作为参照组,Logistic分析小儿病毒性腹泻患者疾病痊愈的危险因素。结果:200例患者中,HAstV感染121例,占60.50%;HAD感染36例,占18.00%;HUCV感染15例,占7.50%;HRV感染10例,占5.00%;混合感染18例,占9.00%。HAstV类型病毒性腹泻患者临床症状以呼吸道症状、发热、呕吐为主;HAD类型病毒性腹泻患者临床症状以发热、呕吐为主;HUCV类型病毒性腹泻患者临床症状以呼吸道症状、发热为主;HRV类型病毒性腹泻患者临床症状以发热、呕吐为主;混合感染类型病毒性腹泻患者临床症状以呼吸道症状、发热、呕吐为主。年龄、中枢神经损害、心肌损害、近1 w是否接触过腹泻是小儿病毒性腹泻患者疾病痊愈的危险因素,P0.05。结论:小儿病毒性腹泻不同感染类型,临床症状各不相同。小儿病毒性腹泻患者预后与年龄、中枢神经损害、心肌损害、近1 w是否接触过腹泻有着极为密切的联系,应当引起临床重视与关注。  相似文献   

11.
Zoologists handling post-mortem material are at risk to infection by a number of potentially dangerous pathogens. The incidence of such infections is small but that is no reason for complacency. The possible sources of infection and precautions to be taken are reviewed and an annotated checklist of potentially dangerous diseases which might be associated with post-mortem material is given.  相似文献   

12.
目的:观察三重措施预防为基础,联合非阿片镇痛药复合静脉全麻在行鼾症手术患者术后恶心呕吐的应用效果。方法:选择择期行鼾症手术男性病人80例,随机分为两组:吸入麻醉组(inhalation group, IHLA组)和静脉麻醉组(intravenous group, TIVA组),每组40例,两组均采用三重措施预防恶心呕吐,IHLA组采用以舒芬太尼为基础复合七氟烷吸入麻醉,TIVA组以氯胺酮和右美托咪定镇痛基础上丙泊酚全凭静脉麻醉。评估两组病人恶心呕吐危险系数,采用李克特量表(Likert scale),记录并分析两组患者术后6~8 h在麻醉后监测治疗室(post anesthesia care unit, PACU)及病房24 h恶心呕吐发生情况及补救用药用量。结果:两组患者一般临床资料、恶心呕吐风险评分、手术时间、术后恢复期补救用药量人数无显著差异(P>0.05);IHLA组在PACU恶心呕吐发生率为39.5%,TIVA组发生率为18.9%,两者相比有显著性差异(P<0.05);IHLA组病房24 h恶心呕吐严重程度高于TIVA组,两组术后需要补救应用抗呕吐药物用量无显著差异(P>0.05)。结论:以三重措施预防为基础,与吸入麻醉相比,非阿片类镇痛药复合静脉麻醉可以减少肥胖病人鼾症手术术后恶心呕吐发生率和严重程度,降低围术期风险,有利于患者早期恢复。  相似文献   

13.
E Seifried  G Gaedicke  G Pindur  H Rasche 《Blut》1984,48(6):397-401
In patients with Haemophilia A, the development of inhibitor is a life-threatening complication of treatment. These patients are at high risk for dangerous bleeding as a result of this acquired resistance to human Factor VIII concentrate. Although treatment of bleeding complications has been improved with the introduction of an activated prothrombin complex preparation, therapy remains unsatisfactory. Two patients with Haemophilia A inhibitor were treated with high dose intravenous immunoglobulin in the expectation of an immunosuppressive effect. A rise in the antibody titre at the same time as the administration of factor VIII concentrate showed that this treatment was ineffective in patients with Haemophilia A inhibitor.  相似文献   

14.
One hundred patients with Parkinson''s disease were treated with levodopa for more than a year at UCLA Medical Center. They were examined at given intervals and their improvement was graded. The optimum therapeutic dose was attained by balancing side effects against relief of symptoms and ranged from 1.5 grams to 8.0 grams per day (average 4.3 grams). There is no doubt that levodopa is the most effective treatment now available for Parkinson''s disease. At the end of the first year, 60 percent of the patients improved 50 percent or better, and 10 percent were considered symptom-free. All major symptoms of this disease, including rigidity, akinesia and tremor, improved in variable degree.There were no serious abnormalities in the routine clinical laboratory tests. The comon side effects included nausea, vomiting and choreoathetoid dyskinesias. The side effects were not life threatening, but occasionally were major therapeutic challenges.Maximal benefits with minimal side effects were achieved only by careful adjustments of the levodopa dosage as the months went by. This needed careful management by the physician and cooperation by the patient. Anticholinergic medications or amantadine hydrochloride, sometimes both, usually supplemented the effect of the levodopa.  相似文献   

15.
The symptoms of many asthmatic patients are poorly controlled, and there are several reasons why this may be so. Doctors fail to find out about symptoms that asthmatic patients are experiencing. Doctors wrongly assume that regular use of bronchodilators in small doses is satisfactory treatment for asthma and that taking high doses of bronchodilator in an asthma attack may be dangerous. Doctors think that inhaled steroids may be dangerous and are reluctant to use them in effective doses. Doctors do not check that patients can use their inhalers properly and do not make enough use of large volume spacers, the best available method for giving inhaled asthma treatment. Doctors undermine patients'' confidence in advice on treatment by failing to ensure that consistent advice is given and often make the management of asthma more troublesome for the patient than the symptoms of asthma.  相似文献   

16.
It is difficult to establish economic thresholds since they vary with current commercial practices. «Indicative intervention thresholds» are used in maize and wheat; these are non-acceptable risk levels. The decision to treat or otherwise may be taken either at a high level (potential risk of high infestation) or for each field (after assessing the pest(s) present). Systematic chemical control appears to be one of the causes of the recent pest population explosions in these two crop plants. There is insufficient knowledge of sampling methods, dangerous pest levels and the role of beneficials —naturally-occurring parasites and predators. Studies must be directed towards the establishment of forecast intervention thresholds and indirect means for evaluating the risk of losses.  相似文献   

17.
Anti-predator behaviors often entail foraging costs, and thus prey response to predator cues should be adjusted to the level of risk (threat-sensitive foraging). Simultaneously dangerous predators (with high hunting success) should engender the evolution of innate predator recognition and appropriate anti-predator behaviors that are effective even upon the first encounter with the predator. The above leads to the prediction that prey might respond more strongly to cues of dangerous predators that are absent, than to cues of less dangerous predators that are actually present. In an applied context this would predict an immediate and stronger response of ungulates to the return of top predators such as wolves (Canis lupus) in many parts of Europe and North America than to current, less threatening, mesopredators. We investigated the existence of innate threat-sensitive foraging in black-tailed deer. We took advantage of a quasi-experimental situation where deer had not experienced wolf predation for ca. 100 years, and were only potentially exposed to black bears (Ursus americanus). We tested the response of deer to the urine of wolf (dangerous) and black bear (less dangerous). Our results support the hypothesis of innate threat-sensitive foraging with clear increased passive avoidance and olfactory investigation of cues from wolf, and surprisingly none to black bear. Prey which have previously evolved under high risk of predation by wolves may react strongly to the return of wolf cues in their environments thanks to innate responses retained during the period of predator absence, and this could be the source of far stronger non-consumptive effects of the predator guild than currently observed.  相似文献   

18.
Inhalation, skin absorption or ingestion of insecticides containing organic phosphorus may result in abrupt onset of serious illness several hours following exposure. Because of the acute onset, often at night, the patients usually are observed by the first available physician rather than by an industrial physician. Prompt recognition and adequate treatment are essential to prevent death.The organic phosphorus radical has the specific effect of inactivating cholinesterase in the body. When cholinesterase is reduced below a critical level continuous stimulation of the entire parasympathetic nervous system results. The major symptoms are diarrhea, vomiting, pulmonary edema, respiratory difficulty and tonic convulsions. Myosis is frequently present and when found is almost pathognomonic, especially if associated with other symptoms.Treatment consists essentially of heroic doses of atropine or a similar parasympathetic inhibitor, plus supportive therapy.Patients who do not die recover rapidly and completely, but they should not risk re-exposure until cholinesterase activity in the blood reaches a static level which may take as long as ten weeks.  相似文献   

19.
Peptic ulcer is a common problem in advanced renal failure, but most drugs for ulcers are hazardous in this condition. In a small open study cimetidine was given to nine patients with acid hypersecretion and endoscopically diagnosed duodenal ulceration who were undergoing haemodialysis. The patients obtained good pain relief and suffered no serious side effects. Both basal and stimulated acid output fell considerably and the plasma gastrin response to food increased during treatment. Two patients with recurrent vomiting during haemodialysis had a striking response to cimetidine, which suggested that such vomiting may be acid-mediated in some patients. These preliminary results suggest that cimetidine may prove to be an advance in the management of peptic ulcer in uraemic patients.  相似文献   

20.
Perhaps the most unpleasant experience following outpatient plastic surgery procedures is postoperative nausea and vomiting. Postoperative nausea and vomiting often results in delayed recovery time and unintended admission, and it can be a contributing factor to the formation of hematoma following rhytidectomy. Ondansetron (Zofran) has proven benefit in preventing postoperative nausea and vomiting if given before general anesthesia in a variety of surgical procedures. Its utility in cases performed under conscious sedation has not been determined. The purpose of this study was (1) to test the ability of prophylactic ondansetron to prevent postoperative nausea and vomiting in plastic surgery cases performed under conscious sedation, and (2) to determine relative risk factors for postoperative nausea and vomiting and a selection policy for the administration of antiemetic prophylaxis. This was a prospective, randomized, double-blind study. One hundred twenty patients were enrolled after giving informed consent. Patients received a single dose of either placebo or ondansetron (4 mg intravenously) before administration of sedation. Sedation administration followed a standardized institutional protocol, using midazolam and fentanyl. Data were recorded from a series of three questionnaires: preoperatively, immediately postoperatively, and at the time of the first office return. Data were confirmed by means of telephone interview, chart analysis, and nursing documentation. Multivariate analysis was conducted. Nausea and emesis occurred with an overall frequency of 33 percent and 22 percent, respectively. Postoperative nausea and vomiting was associated with statistically longer recovery periods. The incidence of emesis was statistically higher among women, among those undergoing facial rejuvenation, and among those with a history of opioid-induced emesis or postoperative nausea and vomiting following a previous operation (p < 0.05). The incidence of postoperative nausea and vomiting paralleled increases in case duration; the incidence of emesis was zero in cases less than 90 minutes in duration. Ondansetron significantly reduced the incidence of emesis overall (placebo, 30 percent; ondansetron, 13 percent; p < 0.05). Postoperative perception of nausea was significantly lower among those who had received ondansetron (p < 0.05). These results confirm the efficacy of ondansetron for the prevention of postoperative nausea and vomiting in plastic surgery cases under conscious sedation. In those who are at increased risk, prophylaxis should be considered. Such risks include female gender, facial rejuvenation procedures, and a patient history of opioid-induced emesis or postoperative nausea and vomiting following a prior operation. The zero incidence of emesis in cases less than 90 minutes does not support the routine use of prophylaxis in such cases. Patient satisfaction in plastic surgery is derived from the overall subjective experience of the event as much as by the final result. By remaining attentive to patient concerns and optimizing perioperative care, we can improve the subjective experience for our patients.  相似文献   

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