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Algunas circunstancias relacionadas con el manejo y las instalaciones de los felinos salvajes en cautividad tales como la introduccin de nuevos animales discount floxin 200mg visa virus epidemic, la existencia de recursos por los que los animales pueden competir y la alteracin de la dinmica social tpica de cada especie pueden aumentar la frecuencia o intensidad de las interacciones agresivas floxin 400mg overnight delivery antibiotic reaction rash. Las tcnicas de enriquecimiento ambiental y generic floxin 400mg with amex antibiotics z pack dosage, de forma ocasional floxin 400 mg lowest price 7dtd infection, la utilizacin de psicofrmacos y de feromonas constituyen las tcnicas principales para prevenir y corregir las alteraciones de comportamiento que aparecen en los felinos salvajes en cautividad. El objetivo principal del enriquecimiento ambiental es facilitar la expresin del comportamiento normal de la especie, especialmente la conducta exploratoria y la interaccin social. Las feromonas faciales y las feromonas apaciguadoras producidas por las hembras lactantes pueden ser especialmente tiles para prevenir o corregir los cambios de conducta causados por el estrs. Such changes generally involve stereotypic behaviour (or stereotypies), the inhibition of maternal behaviour, increased aggressive behaviour, and decreased food consumption and exploratory behaviour. Stereotypies are repetitive behaviours resulting from a disease or repeated attempts to adapt to a diffcult environment. Stereotypic pacing is the most frequent type of stereotyped behavior in wild felids in captivity. It usually appears when the animals are in a situation that prevents or hinders them from expressing their normal behaviour, particularly feeding, moving about, or exploring. A number of studies suggest that when animals are held in environments with few stimuli at an early stage of their development, they are more likely to perform stereotypies as adults. Stress inhibits maternal behaviour and may sometimes cause maternal cannibalism, or interrupt or delay delivery and cause brain hypoxia in the young. Stress caused by an inadequate or new environment often causes anorexia, which may in some cases compromise the animals health or even its life. Some circumstances related to the housing and husbandry of wild felids in captivity, e. Environmental enrichment techniques, and occasionally the use of psychotropic drugs and pheromones, are the main techniques to prevent and correct behaviour problems in captive wild felids. The main objective of environmental enrichment is to facilitate the expression of the normal behaviour of the species, especially exploratory behaviour and social interaction. Facial pheromones and appeasing pheromones produced by lactating females can be particularly useful to prevent or correct behavioural abnormalities caused by stress. More recently, Rushen and Mason (2006) have described them as repetitive behaviours resulting from illness or repeated attempts at adapting to a diffcult environment. Stereotypic behaviour has seldom been described in animals in the wild 129 (carlstead, 1996). However, it is seen relatively frequently in wild animals in captivity, such as farm, companion and laboratory animals. Only stereotypies which occur in response to environmental conditions will be considered in this article. T The stereotypy most frequently exhibited by wild carnivores in captivity is known as pacing. It involves the animal making repetitive movements along an unchanging path, often incorporating a fixed sequence of movements in a specific place. This stereotypy makes up 97% of those described in captive carnivores (clubb and Mason, 2003). The causes of environmental stereotypies have been, and continue to be, the subject of many investigations, and a detailed revision of the neurophysiological mechanisms responsible for such behaviours is beyond the objectives of this article. Briefy, however, it appears that environmental stereotypies tend to be exhibited in situations where expression of normal behaviour is obstructed or made diffcult. In particular, they can appear when the environment prevents the expression of feeding, locomotory or exploratory behaviours. Likewise, some stereotypies seem to derive from an animals attempts to escape the environment in which it is confned; in which case, the behaviour would be a consequence of the aversion caused by the environment (Rushen et al. Finally, stereotypies can also be triggered by the general activation of the central nervous system as a response to unspecifc stimuli (Rushen et al. It is often stated that stereotypies are a consequence of the animal being confned to a very limited space, and can be reduced or even eliminated by simply increasing the space available to the animal. The tendency to perform stereotypies varies considerably between species, and between individuals of the same species. The differences between species can be at least partly related to some aspects of their natural history. Interestingly, neonatal mortality in captivity also tends to be greater in these species than in those which use smaller areas. This would indicate differences between species in terms of the ease in which they are able to adapt to their captive conditions. The differences between individuals within a species can have genetic and environmental origins. Thus, during early stages of development, a complex environment that is rich in stimuli may help prevent the development of stereotypies in later stages, due to greater behavioural flexibility and decreased sensitivity to stressful situations. This could explain the differences, described in some species, between individuals born in captivity and individuals captured in the wild in terms of their tendency to carry out stereotypical behaviours (Jones and Pillay, 2006). Therefore, environmental stereotypies appear in animals with a certain individual or species predisposition, when they fnd themselves in environments that do not allow the expression of certain behaviours. Individual predisposition to perform stereotypies in suboptimal environments would result from a combination of genetic and environmental factors. Stereotypies change over time, and stereotypies that have been performed over a long period, are often more diffcult to stop and are also less responsive to management techniques such as environmental enrichment. Such techniques may be more useful to correct more recently acquired stereotypies (Mason, 1993). However, it is important to bear in mind that stereotypies are not synonymous with a lack of welfare. Indeed, some animals can be found in a state of considerably bad welfare, yet still not develop stereotypic behaviours (Jones and Pillay, 2006). In fact, while environments that are conducive to the development of stereotypies are often inadequate from a welfare point of view, animals in such environments that do not perform stereotypies can have an inferior state of welfare to those who do develop them (Mason and Latham, 2004). Moreover, the importance of stereotypical behaviour from a welfare point of view will vary between long-standing and more recently acquired stereotypies. Si t u a t i o n S o F S t r e S S m a y inhibit t h e e x p r e S S i o n o F maternal b e h a v i o r. Immediately after giving birth there is a sensitive period in which the female is especially receptive to any stimulus from the young. During this time, contact between the female and her young is crucial for maternal behaviour to become independent from hormonal stimuli and be maintained until the young are weaned and independent. One of the most important causes of neonatal mortality in domestic cats is the inadequate expression of maternal behaviour, which can cause up to 19% of all kitten deaths (Young, 1973). A similar situation is highly likely in other felid species, such as the Iberian lynx, where maternal neglect occurs in more than half of frst- time mothers (Vargas et al. As has been previously commented, there are differences between species in terms of survival of young in captivity; species that use larger areas in the wild usually suffer a higher percentage of neonatal mortality in captivity (clubb and Mason, 2003). Stress also has a very important effect on maternal behaviour, sometimes inhibiting its expression, or even leading to flial cannibalism.
Do not expect to have any con- trol over material that you provide 400 mg floxin amex infection 7 months after hysterectomy, press re- The media should be considered as an ally in leases can be selectively quoted and interviews protecting the health of the public best order for floxin antibiotic prices. However journalists are usually one of the most powerful influences upon the interested in accuracy buy floxin 400 mg on line bacteria nitrogen cycle. Jour- Messages nalists often have a similar agenda to public health workers discount 200mg floxin amex antibiotic resistance for dummies, they wish to inform and ed- Decide beforehand what your key messages ucate the public. If they encounter a group of are; if possible discuss these with the journal- professionalswhounderstandtheirneeds,and istanddiscussthequestionsthatwillbeasked. Be honest and accurate, Identifypeoplewithintheorganisationwho keep technical details to a minimum. Get the are particularly good with the media they key message across first, then provide the rea- may not be the most senior people. If you are uncertain of the facts or some detail say so and offer to get the information. Routine relationships Dont be drawn into areas you feel you cannot or should not discuss, be firm and polite and Develop regular contact with your local print say that you cannot discuss that issue. Be available to answer avoid discussions of money and cost saving, their questions, and treat your local reporters stress public health action and your concern asfriends. Avoid be- authoritative source it will make things much ing drawn into speculation, or other criticisms easier if a story is breaking. Behave as if you were always Local papers may be willing to publish a reg- on the record. Make sure that you know if a ular column; this is a powerful way of get- broadcast is live or recorded. Use opportunities to publish in local papers, womens maga- zines, parents magazines etc. This will prob- Press releases ably have a greater influence than publishing in the peer reviewed medical press. Have ba- Keep the press release short (810 paragraphs); sic information packs available for journalists. Outbreaks In the middle expand the story with support- ingdetail,concludebysummarisingandiden- During outbreak or emergency situations it is tifying the next steps. Journalists have a job to do, they can be- come intrusive, but they will understand that Problems you have a job to do. Let the journalists know that they will be kept informed, that there will The press might want access to cases or loca- be regular briefings, daily even twice daily. En- tions such as outbreak rooms for atmospheric sure that the briefings do happen. These requests should media spokesperson and ensure that all media be considered very carefully. The of confidentiality and the smooth running of Clinical governance and audit 327 an investigation must come first. Developinggoodre- The Board of the organisation needs to set lations with the media takes time and effort. It must also errorsoffactappearinanarticleoryoufeelyou take a particular interest in the organisations havebeenmisrepresentedcontactthejournal- strategic capacity to deliver a quality service ist and discuss them; if necessary talk to the andassessandcontroltherisktothatcapacity. This could cover the following areas: Clinical governance emphasises that the or- Service structure, personnel and skills. This Should include relevant operational support should then be discussed with the appropriate fromotherhealthorganisations(e. Each Adequacy of surveillance: data access (time- staff member should have a personal devel- liness, quality), analysis and dissemination. Departments may also wish to invite an ex- non-communicable risks to health (if rele- ternal peer reviewer to comment on how their vant). One useful mechanism is to involve staff revalidation will mean that doctors will need inneighbouringteams,perhapsaspartofaRe- to be able to regularly demonstrate that they gionalAuditGroup. Wherenationalstandards are keeping themselves up to date and remain do not exist, this group can devise regional fit to practise in their chosen field. Section 5 Com unicable disease control in Europe nificantly reinforce the synergies between the 5. Newpatternsofcollab- work, the centre could either use its own staff, oration are developing to enable countries to staff from the dedicated surveillance networks respondappropriatelytointernationalthreats (see Table 5. This has particularly been the case subcontract tasks to a national centre of excel- in Europe. Scientific issues arising in the area of tionalsurveillancesystemscollaboratearound communicable diseases vary widely, ranging a common list of diseases under surveillance, from questions of clinical medicine and epi- commoncasedefinitionsandcommonlabora- demiology through to standardisation of lab- torymethods. Austria 335 that give humanitarian aid or other types of Outbreak detection and assistance in response to disease outbreaks in investigation third-world countries. Physicians notifications and laboratory re- ports are collected at district and regional level. District and regional health administrations have the Contacts legal responsibility for detection, investiga- tion and public health action in co-operation Bundesministerium fur Arbeit, Gesundheit with regional food and veterinary adminis- und Soziales (Federal Ministry for Labour, tration. Public health ofcers are action responsible for contact tracing and contact management. Levels of reporting Local level for reporting: 122 Local Health Departments with an average population of 66,000. Control measures including contact tracing and outbreak investigation is generally the responsibility of the Public Health Service, primarily at local level with support from regional and national level. Data dissemination A list of notiable diseases is published by the Ministry monthly/yearly. District Health Office Statutory notication systems Hard copies (monthly) The details regarding statutory notification systems are given in Table 5. A variety of sources of information are used to detect possible outbreaks (physicians noti- fications/reporting,laboratoryreporting,tele- phone calls from the public). Othernationalauthorities guage and culture, Belgium can be divided may also then be involved. The communities have the re- sponsibility towards control of infectious dis- Prevention/prophylaxis eases. Levels of responsibility At Federal level the Ministry for Public Health is responsible for, e. The administration of these Community governments has a health inspector per province in charge of surveillance and control of infectious diseases. The tasks are registration of notied cases of infectious diseases, co-ordination and follow up of control measures, investigation and follow up of outbreaks and vaccination policy and its implementation. Notiable diseases About 40 diseases are notiable in the three communities and case denitions are in use for each of them. No nancial incentives are given for notifying physicians or laboratories in Belgium. Time to inform national level Regional level: 2448 hours, depending on the specic disease. Public health action The responsibility for case management is held by the treating physician. Control measures including contact tracing and outbreak investigation is generally the responsibility of the Community Health Inspection.
The periorbital changes represent the heliotrope eruption along the eyelid margin cheap floxin 400 mg mastercard antibiotic resistance and public health. The diferential diagnosis for the heliotrope eruption ofen includes an- gioedema or dermatitis generic floxin 400mg online oral antibiotics for dogs hot spots. Tey may also be found overlying the elbows generic 200mg floxin fast delivery antimicrobial hand wipes, knees generic 400mg floxin with visa antibiotic resistance quotes, and / or feet, referred to as Gottrons sign. Tere may be a slight associated scale and on some occasions there is a thick psoriasiform scale. Several other cutaneous features are characteristic of the disease despite not being pathognomonic. Tey include malar erythema, poikiloderma in a photosensitive distribu- tion, violaceous erythema on the extensor surfaces, and periungual and cuticular changes. Nailfold changes consist of periungual telangiectasia and/or a characteristic cuticular change with hypertrophy of the cuticle and small, hemorrhagic infarcts within this hyper- trophic area. Periungual telangiectasia may be clinically apparent or may be appreciated only by capillary microscopy. Poikiloderma (the combination of atrophy, dyspigmentation, and telangiectasia) may occur on exposed skin such as the extensor surfaces of the arm, the V of the neck (Fig. Patients rarely complain of photo- sensitivity, despite the prominent photodistribution of the rash. Poikiloderma of the upper chest in a patient with dermatomyositis 6 Dermatomyositis 247 Fig. Histopathology revealed deposi- tion of massive amounts of mucin in the dermis cally spares these areas. Scalp involvement in dermatomyositis is relatively common and is manifest by an erythematous to violaceous, psoriasiform dermatitis (Kasteler and Callen, 1994). Clinical distinction from seborrheic dermatitis or psoriasis is occasionally difcult, but histopathologic evaluation is helpful. Nonscarring alopecia may occur in some patients and ofen follows a fare of the systemic disease. Rare cutaneous manifestations include vesiculobullous lesions (McCollough and Cock- erell, 1998), an eruption that simulates pityriasis rubra pilaris (Requena et al. In small case series it has been suggested that some of these cutaneous mani- festations may be more common in patients with an associated malignancy. In addition, reports have detailed the fndings of gin- gival telangiectasia (Ghali et al. In general, sclerodermatous cutaneous changes have been the most frequently reported in patients with overlap syndrome, however le- sions of discoid lupus and rheumatoid nodules have also been reported. Pruritus is a common symptom of the skin disease of dermatomyositis and can signif- icantly afect the patients quality of life (Shirani et al. In ad- dition, pruritus is a feature that can occasionally help distinguish dermatomyositis from lupus erythematosus. Clinical observations suggest that not only is the skin disease exacerbated by light, but muscle disease may also be worsened afer sun exposure (Woo et al. However, phototesting has not been able to reliably repro- duce the skin lesions, thus, the wavelength of light that is responsible for the clinical mani- festations (action spectrum) is not known. Patients skin lesions may fare with sun ex- posure, but only some of these patients will have a fare of their muscle involvement. Tus, in many instances the course of the skin lesions does not parallel that of the muscle dis- ease. The myopathy primarily afects the proximal muscles, is usually symmetrical and is slowly progressive over a period of weeks to months. An inability to swallow and symptoms of aspiration may refect the involvement of striated muscle of the pharynx or upper esophagus. Dysphagia or dys- phonia generally signifes a rapidly progressive course and may be associated with poor prognosis. Arthralgias and / or ar- thritis may be present in up to one fourth of patients with infammatory myopathy. The usual picture is one of generalized arthralgias accompanied by morning stifness. The small joints of the hands, wrists, and ankles may be involved with a symmetric nondeforming arthritis. Esophageal disease as manifested by dysphagia is estimated to be present in 15% to 50% of patients with infammatory myopathy. Proximal dysphagia is caused by involvement of striated mus- cle in the pharynx or proximal esophagus. This involvement correlates well with the sever- ity of the muscle disease and is steroid-responsive. Distal dysphagia, which ofen presents as refux, is related to involvement of nonstriated muscle and appears to be more frequent in patients who have an overlap syndrome with scleroderma or another collagen vascular disorder. Dysphagia is associated with a poor prognosis and correlates with the presence of pulmonary involvement. Pulmonary disease occurs in dermatomyositis and polymyositis in approximately 15% to 30% of patients (Marie et al. Lung disease may also occur as a direct complication of the muscle disease, such as hypoventila- tion or aspiration in patients with dysphagia, or may be a result of treatment, such as with opportunistic infections or drug-induced hypersensitivity pneumonitis. In a retrospective review of 70 patients with myositis-associated interstitial lung dis- ease seen at Mayo Clinic between 1990 and 1998, most of the patients presented with either symptoms of lung disease or symptoms of myositis alone, whereas only 15 patients pre- sented with the involvement of both simultaneously (Douglas et al. In general, the lung disease was at frst felt to be a pneumonitis that was antibiotic resistant. Biopsy of the lung revealed non-specifc interstitial pneumonitis or difuse alveolar damage in a major- ity of those who were biopsied. It is unclear exactly how many of these patients had dermatomyosi- tis, but perhaps between 8 and 12. Patients with Jo-1 antibodies (19 of 50 who were tested) had roughly the same fea- tures and prognosis as those who did not have this antibody. Var- ious abnormalities have been described which most commonly include conduction defects and rhythm disturbances. Although congestive heart failure, pericarditis, and valvular dis- ease may occur, they are much less frequent. Depending on the report, cardiac manifes- tations may occur in up to 50% of patients, but only a small proportion of these patients manifest symptoms. It is not known whether the identifcation of asymptomatic abnor- 250 Ruth Ann Vleugels and Jeffrey P. Calcinosis cutis is manifested by frm, yellow-white or skin-col- ored nodules, which ofen occur over bony prominences. Occasionally, these nodules can extrude through the surface of the skin, in which case secondary infection may occur. Cal- cifcation of the muscles is ofen asymptomatic and may be seen only on radiological ex- amination. In severe forms, the calcinosis can cause loss of function, and rarely, bone for- mation is possible.
The maturation of B-cells in this more public environment has important implications for the mecha- nisms that maintain self-tolerance and contribute to the development of autoimmunity best 200 mg floxin medication for uti pain over the counter. This type of development allows for the shaping of the B-cell repertoire with multiple specificities cheap floxin online mastercard bacteria 37 degrees celsius, including weakly autoreactive and crossreactive specificities cheap floxin online amex antibiotic names for uti, into the func- tional repertoire buy 400 mg floxin mastercard bacteria found in water. The evolution of the humoral immune system was challenged by hav- ing on hand as diverse an array of antibody-producing cells as possible to address the multiple types of invaders discussed earlier. Much of T-cell development occurs in the thymus, geographically sequestered from the sites of active immune responses. This cloistered environment ensures that many self-reactive T-cells are eliminated before joining the mature T-cell repertoire. B-cells also undergo several forms of negative selection of self-reactive specificities. Recent experiments suggest that, in contrast to T-cell development, much B-cell negative selec- tion occurs in the same location in which immune responses to foreign antigens are initiatedthe outer T-cell zone of the spleen (reviewed in ref. This maturation of B-cells in a public environment has important implications for the mechanisms that maintain self-tolerance and that might contribute to the development of autoimmune disease. Here, we suggest that the public shaping of the B-cell repertoire allows the recruitment of multiple specificities, including weakly self-reactive specificities, into the functional immune repertoire and that this mechanism for increasing repertoire diversity offsets the risk of autoimmunity. B-cell selection, like T-cell selection, functions to balance the need for repertoire diversity with the need to protect against autoimmunity. T-cells and B-cells recognize antigen in fundamentally different ways, and these differences in recognition are reflected in differences in the mechanisms of repertoire generation. Signals to the T-cell that stimulate activation of T-cell immune responses in the periphery induce deletion of maturing, self-reactive cells in the thymus (25). Thymic T-cells that have yet to complete development and selection are prevented from joining the functional immune repertoire; the cloistered environment of the thymus thus protects against autoimmunity. Humoral Immunity 17 In contrast to T-cell recognition, B-cells recognize native antigen that is not neces- sarily associated with cells. B-cell development also begins in an isolated environment in the bone marrow, where high avidity self-reactive B-cells are deleted (26,27). Although it was generally thought that most B-cell-negative selection occurred in the bone marrow (28), several lines of evidence point to a key distinction from T-cell devel- opment. First, the bone marrow appears to export a larger proportion of the B-cells that it produces than the thymus (29,30). These newly exported B-cells are relatively imma- ture cells that migrate from the bone marrow to the outer T-cell zones of the white pulp of the spleen (31). This splenic restriction point in B-cell production eliminates unwanted B-cells by the same order of magnitude as occurs for T-cells exclusively in the thymus. A key question is whether immature B-cells are selected against within the splenic T-cell zone because they fail a positive selection step for particular specificities or because they trigger a negative selection step against particular specificities. The first evidence that immature B-cells are negatively selected in the spleen came from Cyster et al. Self-reactive cells that are excluded from the follicular recirculating repertoire are short lived (13 days), whereas, cells that enter the B-cell follicles are long lived and recirculate for 14 weeks (42). They also show that these autoreactive cells localize to the interface between the B-cell and T-cell zones of the spleen. Together with the lysozyme model antigen data, and the evidence that many immature cells are competitively selected against at this site, it seems likely that B-cells bearing many different autore- active specificities will join the peripheral B-cell population and be subject to selection at this stage and site within the spleen. The exclusion of newly produced autoreactive B-cells from the B-cell follicles places these potentially pathogenic cells in a site known to be important for the initia- tion of antibody responses to foreign antigensthe outer T-cell zone (46, 47). Indeed, autoantibody-producing cells in autoimmune mice appear and accumulate in the outer T-cell zone (48), and it has been proposed that the pathogenic autoantibody production results from a failure of B-cell tolerance in this site (49). Nevertheless, antigens with high avidity binding can deliver strong sig- nals to the B-cells that partially override anergy and induce modest proliferation and antibody production by maturing self-reactive B-cells (50). Thus self-reactive B-cells that have yet to complete development and negative selection might be recruited into the functional immune repertoire if they crossreact avidly with a foreign antigen; the public environment of the spleen seems to encourage this recruitment at the risk of autoimmunity. Why risk autoimmunity by requiring so much of B-cell-negative selec- tion to occur where immune responses begin? In any one individual in a popula- tion, at a particular time, a proportion of the B-cell repertoire is contained in the short- lived B-cell pool, being excluded from entry into the B-cell follicles. In the absence of infection, self-reactive cells within this population will die within a few days and so pose little risk of causing a pathogenic autoimmune response. Autoimmunity is also avoided by requiring stronger signals to recruit autoreactive B-cells into an immune response than are required to recruit naive B-cells and by producing smaller bursts of progeny when autoreactive cells clear the higher activation hurdle (50). Accordingly, each individual within a popula- tion will express a different B-cell repertoire, with varying propensity toward autoim- munity when an infectious agent appears. The repertoire diversity provided by the short-lived pool of B-cells might work in concert with the probable differences in B-cell pool composition between individuals to ensure that some individuals will mount effective B-cell responses against an infec- tion. This solution to plugging the holes in the repertoire might be buttressed by the unique ability to fine-tune B-cell specificity further, by hypermutation and additional rounds of negative selection in germinal centers. The independent processes of anergy and negative selection in germinal centers might account for why these modest autoan- tibody responses do not achieve high concentrations and do not normally exhibit sus- tained or recall characteristics. The effectiveness of this system depends on the availability of a diverse pool of B-cells within each individual at any one time, as well as differences in pools be- tween individuals. Whereas T-cell deletion in the thymus helps to protect against self- reactivity within the T-cell repertoire, the inherent short lifespan and more rigorous signaling requirements of self-reactive B-cells helps to protect against self-reactivity within the B-cell repertoire. Seen in this light, there might be a clear Humoral Immunity 19 advantage to transiently maintaining weakly self-reactive B-cells in the periphery, where they can potentially contribute to an acute immune response to infection. One source of these relatively low-avidity autoantibodies is likely to be activation of short-lived B-cells in the outer T-cell zone by high-avidity foreign antigens. The relative contribution of these preex- isting reactive B-cells to total repertoire diversity is not known; however, their influ- ence on disease resistance and susceptibility are profoundly observed during the parasitic infection known as leishmania in mice. Experimental leishmaniasis offers a well-characterized model of Th1-mediated con- trol of infection by an intracellular organism. It appears the T-cells were initially derived to a specific and crossreactive antigen found on a bacterial species col- onizing the mouse gastrointestinal tract during its early lifetime. Thus, T-cells that are activated early and are reactive to a single antigen play a pivotal role in directing the immune response to the entire parasite. Thus, breakthroughs in our knowledge of humoral immunity may be coming with our understanding of its development during differentiation and initial repertoire devel- opment as the host establishes itself in the environment. It seems that successful pathogens may have explored these subtle overlaps between self and the normal colo- nizing flora, which in a distant way is part of self in that they permit the survival of the host through numerous important symbiotic mechanisms (5759). Ueber Zusttandekommen der Diptheria-Immunitat und der Tetanus-Immuniat bei Thiern. A possible role of pre-existing IgM/IgG antibodies in deter- mining immune response type.