255 THE ROLE OF GERIATRIC MEDICINE IN CARE OF OLDER ADULTS WITH MAJOR TRAUMA

Background

In recent Major Trauma Audit Reports the most common cause of major trauma is low falls, 46-49% of injured patients were aged over 65. These are an important group to identify and to prioritise for geriatrician led MDT care. There is currently no specialist geriatric medicine service in Ireland for older adults with major trauma. We aimed to evaluate patients with major trauma currently co-managed by orthopaedic surgery and geriatric medicine, the role of geriatric medicine and the potential role of a major trauma geriatric service.

Methods

We reviewed local data collected for the Irish Hip Fracture Database to examine the incidence of major trauma presenting in older adults and the role of geriatric medicine. We included patients who had injuries in addition to hip fracture including radius, ulna, clavicle, humerus, rib, vertebra, pelvis fracture subdural haemorrhage, diffuse brain injury and traumatic subarachnoid haemorrhage.

Results

In 2020, there were 437 older adults admitted with hip fractures and likely 2185 patients presenting with fragility fractures. We identified 32(7%) patients who sustained other major injuries in addition to hip fracture. Nationally, these patients have a higher in-hospital mortality (11% v 5%). All of these patients had comprehensive geriatric assessment (CGA) and geriatrician-led MDT care. These patients are at high risk for poorer outcomes; delirium, pressure ulcers, hospital acquired infection and disability, prolonged length of stay, delayed transfers of care, premature institutionalisation and death.

Conclusion

There is a role for expansion of proactive early identification and geriatric medicine input for all older adults with major trauma, in addition to those with hip fractures and other injuries. The increased mortality in these patients has not previously been published. International evidence supports early intervention from a specialist geriatric medicine service, with CGA to provide exceptional, continuous and co-ordinated care.

68 DEVELOPMENT OF AN IRISH HIP FRACTURE DATABASE FRAILTY INDEX: ASSOCIATIONS WITH LENGTH OF STAY, DELIRIUM, MORTALITY AND NURSING HOME ADMISSION

Background

In older people, hip fracture can lead to adverse outcomes. Frailty, capturing biological age and vulnerability to stressors, can indicate those at higher risk. This study aimed to derive a frailty index (FI) in the Irish Hip Fracture Database (IHFD), to explore associations with prolonged length of hospital stay (LOS ≥ 30 days), delirium, inpatient mortality and new nursing home (NH) admission and to assess whether the FI added value to those predictions above and beyond age, sex, and pre-operative American Society of Anaesthesiology (ASA) score.

Methods

A 21-item FI was constructed with 16 dichotomous comorbidities, three 4-level ordinal pre-morbid functional variables (difficulty with indoor mobility, outdoor mobility, and shopping), and nursing home provenance (yes/no). The FI was computed as the proportion of items present, and divided into tertiles (low, medium, high risk). Independent associations between FI and outcomes were explored with logistic regression, from which we extracted adjusted Odds Ratios (aOR) and areas under the curve (AUC).

Results

From 2017-2020, the IHFD included 14,615 hip fracture admissions, mean (SD) age 80.4 (8.8), 68.9% women. Complete FI data was available for 12,502 (85.5%). By FI tertile (low to high risk), prolonged LOS proportions were 5.9%, 16.1% and 23.1%; delirium 5.5%, 13.5% and 17.6%; inpatient mortality 0.6%, 3.3% and 10.1%; and new nursing home admission 2.2%, 5.9% and 11.3%. All associations were statistically significant (p<0.001) independently of age and sex. AUC analyses suggested that the FI score, added to age, sex, and ASA score, added value to the prediction of delirium and new NH admission (p<0.05), and especially to prolonged LOS and inpatient mortality (p<0.001).

Conclusion

A 21-item FI in the IHFD was a significant predictor of outcomes and added value to traditional risk markers. The utility of a routinely derived FI to more efficiently direct limited orthogeriatric resources requires further investigation.

1027 DEVELOPING A MINIMUM COMMON DATASET FOR HIP FRACTURE AUDIT

Introduction

National hip fracture audits share a common heritage in the work of Rikshöft and the Standardised Audit of Hip Fracture in Europe. However, as more countries develop audit programmes and these evolve to address local needs, divergence in the data they collect compromises their scope for learning from clinical, audit and quality improvement work in other nations.

Method

In 2021 we compared all ten established national hip fracture audits: England/Wales/Northern Ireland; Scotland; Australia/New Zealand; Ireland; Germany; the Netherlands; Sweden; Norway; Denmark; Spain. We tabulated all questions included in each, and cross-referenced them against the 32 questions of the minimum common dataset (MCD) defined by the global Fragility Fracture Network (FFN) in 2014. We identified those consistently used in most national audits, and additional fields that might need to form part of a revised MCD. Any MCD must meet the needs of both developed and developing countries. We presented these findings at the Asia-Pacific FFN meeting, and used an online questionnaire to capture feedback from different countries. A draft revision was presented at the Global FFN conference in September 2021, with feedback again used to finalise this revised MCD.

Results

We tabulated a total of 215 possible questions. Only 72 (34%) were used in >1 national audit, and only 32 (15%) by more than half of audits. Adherence to the 2014 MCD was disappointing; all 32 fields were used by at least one audit, but 5/32 only by one audit. Only 21/32 (65%) were used in the majority, and only three (anaesthetic grade, operation and date/time of surgery) by all ten established audits.

Discussion

This revised MCD will help aspirant nations establish new audit programmes, facilitate the integration of novel analytic techniques and greater multinational collaboration, and serve as an internationally-accepted standard for monitoring and improving hip fracture services.

Cost of hospitalisation for hip fracture-findings from the Irish hip fracture database

The authors utilised the Irish Hip Fracture Database (IHFD) to quantify the impact of hip fracture on the health service in terms of incidence, bed days and financial costs. The absolute number of hip fracture cases recorded by the IHFD has increased, as has the associated costs of hospitalisation.

INTRODUCTION

Hip fracture places a considerable clinical and financial burden on the healthcare system, with acute hospitalisation accounting for a substantial proportion of the costs incurred. This paper aimed to quantify the cost of hospitalisation for hip fracture in Ireland in terms of bed days and direct hospital costs.

METHODS

The authors analysed 23,494 cases in the Irish Hip Fracture Database (IHFD) from 2014 to 2020. Case numbers and length of stay were analysed annually. Hospital costs for hip fracture were described using the 2020 Activity-Based Funding Price List, which outlines the fees paid to public hospitals for inpatient activity.

RESULTS

For the time period 2014-2020, the total cost of hospitalisation for hip fracture was approximately €296 million, equating to approximately €11,700 per episode of care. The annual cost of hospitalisation increased from approximately €34 million in 2014 to €44 million in 2020. In 2020, the mean length of stay for hip fracture was 17 days accounting for > 62,600 acute hospital bed days.

CONCLUSION

The absolute number of hip fracture cases recorded by the IHFD has increased, as has the cost of hospitalisation. Given the current capacity issues and economic constraints, there is a growing need to prioritise time spent in the most expensive acute hospital setting to the immediate perioperative period and maximise the use of community services and early supportive discharge for the rehabilitation phase.

210 A SYSTEMATIC REVIEW OF LONG-TERM OUTCOME COLLECTION FOLLOWING HIP FRACTURE IN IRELAND FROM 2005 TO 2021

Background

The Irish Hip Fracture Database (IHFD) drives clinical improvements across 16 acute hospitals for over 3,500 patients annually. The IHFD aims to begin recording long-term outcomes. Past practice in Ireland could inform this activity. This review aims to identify and summarise studies that have collected long-term outcomes following hip fracture in Ireland.

Methods

A search of electronic databases (MEDLINE, Embase, Scopus, Web of Science, CINAHL) and grey literature was conducted in July 2021 for articles, abstracts, theses and reports. Search terms related to hip fracture and Ireland. Studies published from 2005–2021 were included if post-hospital discharge data were collected in the Republic of Ireland for patients with hip fracture. Study and patient characteristics, data collection methods and long-term outcomes were extracted.

Results

From all sources, 21 articles, 3 theses and 84 abstracts from 18 clinical sites were identified. Numbers of patients with hip fracture ranged from 9 to 2,483 (median 168) across publications. The most common outcome recorded was mortality (59% of publications), most frequently at 30 days and/or one year. Ascertainment methods for mortality included electronic patient records, online death notices, phone calls to family or general practitioners and the national death register. Non-mortality long-term outcomes were assessed in 64% of publications, most commonly through outpatient or virtual clinics or phone calls. They included place of residence, function, mobility and bone-health status at time-points of 30 days, 6 weeks, 3, 4, 6 or 12 months. Only 11 publications followed patients past the 1 year time-point. One third of publications did not report data collection methods.

Conclusion

Meta-analyses of results will provide estimates of mortality rates and other key hip fracture outcomes. Some long-term outcomes have been collected at most hospitals treating acute hip fracture in Ireland in the last 15 years. Qualitative research in needed to identify facilitators of follow-up to inform practice nationally.

Discharge destination after hip fracture: findings from the Irish hip fracture database

PURPOSE

Although home continues to be the place from which the majority of patients are admitted, less than one third of patients are Discharged Directly Home (DDH) following hip fracture. Once ready for discharge, DDH as opposed to Discharge to an Alternative Location (DAL), i.e., community care, rehabilitation facility or long-term care, is a high priority for patients and clinicians alike. Not only is DDH integral to the quality of life of patients, it is also an essential driver of the socioeconomic cost of hip fracture care.

METHODS

We analysed 21,819 cases in the Irish Hip Fracture Database from 2013 to 2019. Descriptive and analytical statistics were conducted.

RESULTS

29% (n = 6476) of patients were DDH during the study period. On multivariate analysis, the odds of DDH decreased as age increased (OR 0.28, p < 0.01, 95% CI 0.24-0.34). Patients who were independently mobile prior to fracture were 47% more likely to be DDH (OR 1.47, p < 0.01, 95% CI 1.29-1.68). Those mobilised early post operatively were 24% more likely to be DDH (OR 1.24, p < 0.01, 95% CI 1.06-1.45). Patients who waited > 72 h prior to surgery were 30% less likely to be DDH (OR 0.70, p < 0.01, 95% CI 0.56-0.88).

CONCLUSION

The authors identified patient characteristics that increased the likelihood of DDH, i.e., younger patients independently mobile prior to fracture, who received timely surgery and early post-operative mobilisation. The Irish Hip Fracture Standards (IHFS) incorporate 2 out the 3 modifiable factors identified, which reinforces the importance of the IHFS in improving patient outcomes.

Characteristics of Centenarians in the Irish Hip Fracture Database

Aim Hip fractures are common amongst older people and result in significant morbidity and mortality. The Irish Hip Fracture Database (IHFD) collects data, from the 16 trauma orthopaedic units in Ireland, on patients aged 60 years and older who sustain hip fractures. This study aims to describe the characteristics of those patients aged 100 years and older in this database. Methods A retrospective analysis of the IHFD from 2012 to 2017. Characteristics of those patients aged 100 years and over were collected and analysed. Results 57 patients were identified for inclusion, 52 (91%) of which were women. Mean age was 101, while mean length of stay was 22.6 days. 51 (89%) fractures were due to low velocity trauma, consistent with likely high rates of osteoporosis in this group. The great majority underwent operative intervention. 50 (88%) were discharged alive. Fracture type varied widely. Only 24 (42%) patients were documented to have been seen by a geriatrician during admission. There were low reported rates of co-morbid medical conditions, likely due to lack of recorded data, rather than true low rates of co-morbidities in this group. Discussion This study provides insight into this distinct group of people, with important implications for future healthcare planning and budgeting.

Trends in hip fracture care in the Republic of Ireland from 2013 to 2018: results from the Irish Hip Fracture Database

Hip fractures continue to be one of the most serious and costly injuries suffered by older people globally. This paper describes the development of a national hip fracture audit and summarises the first 6 years of data from the Republic of Ireland. This can help inform care, standards and outcomes of hip fracture patients.

INTRODUCTION

Ireland has one of the highest standardised rates of hip fracture in the world behind northern European countries. The Irish Hip Fracture Database (IHFD) was established in 2012 to drive clinical and organisational improvements in quality and effectiveness of hip fracture care. This paper describes the progression of the IHFD between 2013 and 2018 and identifies trends and areas for improvement.

METHODS

The IHFD is a clinically led, web-based audit, with data collected through the national Hospital Inpatient Enquiry (HIPE) electronic system, the principal source of information from publicly funded acute hospitals in Ireland. Eligible cases are aged ≥ 60 years with hip fracture as defined by IHFD or with other specified hip fracture excluding periprosthetic fractures. As of 2015, all 16 trauma-receiving hospitals within Ireland submitted data. Demographics and adherence to six national quality standards are described.

RESULTS

A total of 17,983 cases were included in the analysis. National coverage has increased from 63% in 2013 to 99% in 2018. Demographic characteristics are unchanged, but higher levels of comorbidity are seen. Internal fixation and hemiarthroplasty are the most common modes of surgical repair with two-thirds of cases receiving spinal rather than general anaesthesia. Increasingly patients are being assessed by a geriatrician (11% in 2013 to 69% in 2018) and receive a bone health assessment (65% in 2013 to 84% in 2018).

CONCLUSION

While some hip fracture standards have improved, further improvements are required to compare favourably internationally. Reduction of surgical delay and ensuring early mobilisation post-operatively are immediate priorities for the IHFD.

Predictors of in-hospital mortality post hip fracture in Ireland 2013-2017

Background

Hip fractures are associated with considerable mortality, morbidity and healthcare expenditure. There are approximately 3,500 hip fractures in Ireland per annum with this figure set to increase considerably over the coming years due to the ageing population. Internationally, mortality following hip fracture is approximately 10% at 1 month and 30% at 1 year, with less than half of survivors regaining their preoperative level of function. The authors aimed to identify the determinants of in-hospital mortality post hip fracture in the Republic of Ireland 2013-2017, with specific reference to the Irish Hip Fracture Standards.

Methods

A secondary analysis of 15,603 patients in the Irish hip fracture database was conducted.

Results

31% (n = 4,769) were male and 69% (n = 10,807) were female. Mean age for males was 75 years (SD 13.5) and 79 years for females (SD 10.5). The largest proportion of hip fractures occurred in the 80-89 age category, with 72.3% (n = 4,600) of these being female. Median in-hospital mortality was 4.7% (n = 711) (Range 2.7-6.2). Univariate logistic regression revealed 11 statistically significant predictors of in-hospital mortality; however, only 4 remained statistically significant on multivariate analysis [mobilised day of/after surgery (OR 1.46, 95% CI 1.25-1.70, p &lt; 0.000), pre-fracture mobility (OR 0.84, 95% CI 0.79-0.89, p &lt; 0.000), gender (OR 0.56, 95% CI 0.41-0.76, p &lt; 0.000) and age (OR 1.05, 95% CI 1.03-1.06, p &lt; 0.000)].

Conclusions

Older males with poor pre-fracture mobility who were not mobilised the day of/after surgery had the highest risk of in-hospital mortality. The ability to be mobilised on the day of/after surgery is a good composite measure of both patient and organisational factors in hip fracture care. This research supports the inclusion of mobilisation on the day of/after surgery as a new formal best practice standard.

Key messages

Patients not mobilised on the day of/after surgery are 46% more likely to die in hospital. In-hospital mortality of 4.7% in Ireland is comparable internationally. None of the IHFSs significantly influenced in-hospital mortality after multivariate analysis, but may well affect other outcomes such as ability to return home.

Successful use of endoscopy for transcervical cannulation procedures in the goat

Two methods for transcervical cannulation of the goat were evaluated during a contraception study in 15 adult female Nigerian dwarf and African pygmy goats. Twenty-four transcervical cannulation procedures were conducted in which seven females underwent the procedure 2–3 times. Initially, a rigid 4-mm stainless steel cannula and external light source were used in 19 procedures to introduce the contraceptive compound into the uterus. Placement of the cannula was directed by feel or depth assessment. Of seven females that were euthanized following this procedure, four evidenced complications including penetration of the cervix with the cannula and cervical damage. A 2-mm custom-made endoscope with a specially designed cannula was then used for the remaining five procedures. No complications were found. A single animal, that underwent the endoscopic procedure twice, was euthanized for study purposes and no abnormal findings of the reproductive tract were reported. The use of an endoscope resulted in better outcomes because the uterus could be visualized after traversing the cervix.

Host recognition of fetal antigens: do they induce specific antibodies?

The purpose of this study was to ascertain whether the protection afforded to adult mice against the induction and growth of 3-methylcholanthrene-induced tumours by prior exposure to syngeneic fetal cells has an immunological basis. Adult CBA mice were inoculated with fetal cells according to a variety of protocols and the sera were tested for their ability to bind to fetal and adult tissue cells, using a staphylococcal protein A binding assay. All 10 sera tested showed some degree of binding though this varied from strong to weak, and there was some cross-reactivity with adult thymic cells but relatively little with adult spleen cells. Absorption studies were carried out with one of these sera and with two others raised against testicular and thymic cells, respectively. The absorption patterns obtained so far suggest that fetal cells possess at least three, and possibly up to five, distinct antigens. Although none of the anti-fetal sera were produced with a sensitizing protocol identical with that used in in vivo protection, some of them were so close as to suggest that protection is associated with, and perhaps causally related to, these IgG antibodies. The in vitro evidence presented here, together with the in vivo data of P. B. Medawar & R. Hunt, shows that antigens are shared between fetal cells and adult thymic and testicular cells. It therefore lends support to the notion that the production of a vaccine against anaplastic neoplasms, using immunogens derived from adult tissues, is within the realms of possibility.

The rehabilitation of captive baboons

Eleven baboons who had been singly housed indoors for an average of 5 years were moved to outdoor social groups in an attempt to provide a more species-typical environment and reduce high levels of abnormal behavior. Nine of the baboons were observed while in single housing and, over a 6-month period, while housed outdoors socially to document long-term changes in behavior. Abnormal behavior decreased significantly from an average of 14% of the observation time in the single cages to 3% in the sixth month of social housing. Cage manipulation and self-directed behaviors also significantly decreased, while social behavior, enrichment-directed behavior, and locomotion increased in social housing. Baboons that had been in long-term indoor single housing were able to reproduce and form stable social groups without injury. This study provides evidence that even behaviorally disturbed nonhuman primates can be successfully rehabilitated to live in social groups.

Variables influencing the origins of diverse abnormal behaviors in a large sample of captive chimpanzees (Pan troglodytes)

The developmental origin of abnormal behaviors is generally associated with early rearing environments that lack sufficient physical and sensory stimulation. However, other factors should also be considered. A large sample of captive chimpanzees (128 males and 140 females) was surveyed for the presence or absence of 18 abnormal behaviors. Origin variables included the subject's source (zoo, pet, performer, or laboratory), rearing (mother- or hand-reared), and sex. Animals were assessed while held at the Primate Foundation of Arizona, University of Texas M. D. Anderson Cancer Center, or White Sands Research Center. There was a confound among origin variables; more hand-reared animals than expected were from laboratories. Logistic regression tested the relationship of rearing and source, with sex as a secondary predictor variable, to each of the abnormal behaviors. There was no clear association between any abnormal behavior and source. However, for coprophagy, relative to animals from the laboratory, zoo animals tended to show a higher prevalence, while performers tended to show a lower prevalence (when rearing and sex were controlled). Rocking and self-sucking were significantly more likely in hand-reared animals. Coprophagy and depilation of self were significantly more likely in mother-reared animals. When rearing and source were statistically controlled, the only significant sex difference was a higher prevalence of coprophagy in females and a higher prevalence of rocking in males. In a second, smaller sample of 25 males and 33 females from Southwest Foundation for Biomedical Research, no significant sex association was found for coprophagy, urophagy, rocking, or self-depilation. In this second sample, coprophagy was also significantly more likely in mother-reared than hand-reared subjects. The association of some abnormal behaviors with mother-rearing suggests that some form of social learning may be involved in the origin of some of these behavior patterns. This indicates that some abnormal behaviors may not be always be indicative of reduced psychological well-being in captive chimpanzees.

Variables influencing the origins of diverse abnormal behaviors in a large sample of captive chimpanzees (Pan troglodytes)

The developmental origin of abnormal behaviors is generally associated with early rearing environments that lack sufficient physical and sensory stimulation. However, other factors should also be considered. A large sample of captive chimpanzees (128 males and 140 females) was surveyed for the presence or absence of 18 abnormal behaviors. Origin variables included the subject's source (zoo, pet, performer, or laboratory), rearing (mother- or hand-reared), and sex. Animals were assessed while held at the Primate Foundation of Arizona, University of Texas M. D. Anderson Cancer Center, or White Sands Research Center. There was a confound among origin variables; more hand-reared animals than expected were from laboratories. Logistic regression tested the relationship of rearing and source, with sex as a secondary predictor variable, to each of the abnormal behaviors. There was no clear association between any abnormal behavior and source. However, for coprophagy, relative to animals from the laboratory, zoo animals tended to show a higher prevalence, while performers tended to show a lower prevalence (when rearing and sex were controlled). Rocking and self-sucking were significantly more likely in hand-reared animals. Coprophagy and depilation of self were significantly more likely in mother-reared animals. When rearing and source were statistically controlled, the only significant sex difference was a higher prevalence of coprophagy in females and a higher prevalence of rocking in males. In a second, smaller sample of 25 males and 33 females from Southwest Foundation for Biomedical Research, no significant sex association was found for coprophagy, urophagy, rocking, or self-depilation. In this second sample, coprophagy was also significantly more likely in mother-reared than hand-reared subjects. The association of some abnormal behaviors with mother-rearing suggests that some form of social learning may be involved in the origin of some of these behavior patterns. This indicates that some abnormal behaviors may not be always be indicative of reduced psychological well-being in captive chimpanzees.

Cage Toys Reduce Abnormal Behavior in Individually Housed Pigtail Macaques

As part of a behavioral intervention program that identifies and treats individual nonhuman primates exhibiting abnormal behavior, five individually housed pigtail macaques (Macaca nemestrina) were provided with multiple cage toys in an effort to reduce high levels of abnormal behavior. Ten 30-min observations of each subject were conducted during the baseline condition and again after novel toys were presented, both loose inside the cage and attached to the outside of the cage. The new toys were used during 27% of the observation time. Kong Toys were used most consistently by the macaques during the 5-week observation period. Significant decreases in abnormal behavior and cage-directed behavior, as well as significantly increased enrichment use, were evident after the toys were added. Several of the toys were destroyed quickly, and individual differences were evident in the levels of enrichment use and abnormal behavior. Providing multiple manipulable toys as enrichment for pigtail macaques was effective in reducing abnormal behavior and was an important part of an environmental enrichment program for monkeys who could not be housed socially.

Destructible Toys as Enrichment for Captive Chimpanzees

The use of destructible objects or toys as enrichment for nonhuman primates has had promising results in terms of increased use and positive behavioral effect. The purpose of this project was to determine the use and durability of a number of inexpensive, destructible toys provided one at a time or several at once. Nine singly caged chimpanzees were provided with 8 different toys made of plastic, vinyl, or cloth, and the frequency of use of the toys was determined during 15 min trials 2 times per day. A toy was removed when it was destroyed or when it was not contacted during 4 trials. The chimpanzees contacted the toys an average of 11 times per trial, and the use of the individual toys was significantly higher when provided 1 at a time rather than all at once. Use of the toys was fairly stable over time, and the toys remained in the cages an average of 3.2 days. The durability of the toys was related to the type of toy (e.g., more flexible cloth and vinyl toys lasted longer than rigid plastic toys). The destructible toys were used significantly more often than other permanent cage toys or televisions. Toy use was not related to age, level of abnormal behavior, or use of existing permanent toys or television. The implications of the results were related to the management of an environmental enrichment program and indicated that the provision of flexible, inexpensive toys 1 at a time can be an effective method of enrichment for captive chimpanzees.

The discovery of immunologic tolerance

The phenomenon of tolerance can be said to have begun with the seminal observations in 1945 by R. D. Owen that cattle dizygotic twins display red cell (chimerism--mosaicism as he called it--in adult life. Owen interpreted this extraordinary finding in terms of the much earlier discovery by F. R. Lillie that the placentae of cattle dizygotic twins undergo anastomosis early in fetal life, and he speculated that this would have permitted blood cells and their precursors to move from one twin to the other. Owen's discovery came out of the blue and it was ignored by immunologists until F. M. Burnet and F. Fenner highlighted it four years later in their influential monograph The Production of Antibodies, in which they predicted the existence of tolerance as a general phenomenon and developed their notion of "self-markers" to explain why the body does not react against self. Though it was Medawar's group that showed conclusively in 1953 that tolerance can be experimentally induced in fetal mice and in chick embryos, their entry into this field came from a totally different direction, an attempt to distinguish between mono- and dizygotic cattle twins by the exchange of skin grafts. This led to the seemingly paradoxic result that grafts exchanged between dizygotic twins were accepted (1951) and it was not until their cattle experiments had been virtually completed that they became aware of Owen's earlier discovery. Following the work of Billingham, Brent, and Medawar, and of Hasek, tolerance became incorporated into general immunologic theory and it helped to explain the fact that mammals do not normally suffer from injurious autoimmune manifestations. Ray Owen's discovery therefore has a secure place in the history of immunology.

The response of group-housed baboons to three enrichment toys

The behaviour of group-housed baboons was compared before and after the provision of durable cage toys. One adult male hamadryas baboon and 13 adult female olive baboons living in a large enclosure were observed after they were given seven nylon bones, seven Kong toys and seven Plaque Attackers. Observations were conducted four times per week on each subject over a 6-week period. Abnormal, cage-directed, inactive and self-directed behaviours all significantly decreased after the provision of the toys, while enrichment-directed activities significantly increased. Aggression did not differ between the no toy and toy conditions. Approximately 26% of the baboons were using the toys at any one time, and use of the Kong toys and the bones was higher than that of the Plaque Attackers. Individuals who used enrichment structures already present were also those who used the new toys the most.

The Influence of Siblings On Wild Infant Chimpanzee Social Interaction

Abstract

The presence or absence of older siblings influenced the social interactions of 17 wild infant chimpanzees between the ages of 6 and 24 months living at the Gombe National Park, Tanzania. The total amount of time spent in social interaction (contact, grooming and play) was similar for infants with and without siblings, as was the overall level of social interaction with the mother. However, subjects with siblings spent more time with their siblings, while subjects with no siblings interacted with other group members. These results indicate a possible set-point for infant chimpanzee social interaction. Developmental changes were also similar in both groups, but the infants with siblings had lower levels of interaction with the mother and higher levels of interaction with other group members during the age period of 12-18 months. The levels of social behaviors were not related to the sex of the infant.

Quantitative Studies on Tissue Transplantation Immunity. III. Actively Acquired Tolerance

'Actively acquired tolerance' introduces into immunology the concept of a specific inhibition of response. Tolerance of a tissue homograft comes about when an animal has been confronted in foetal life with cells taken from its future donor, or from some other member of the donor's inbred strain (section 3.1). It depends (a) upon an embryo's inability to respond to antigens by becoming immunized, and (b) upon its continued inability to do so in later life. Methods for inducing tolerance in mice (sections 3.2, 4.1, 9), rats and rabbits (section 3.4), and birds (sections 3.3, 5, 7) are described in full. In normal development, response to an antigenic stimulus by becoming tolerant gives way to response by becoming sensitized or immune. The transition from the one modality of response to the other occupies a 'null period' during which the exposure of animals to an antigenic stimulus has no appreciable effect. Most but not all mice and birds at birth or hatching have already entered this transitional period (sections 4.1, 5). Tolerance is antigenically specific. An animal injected in foetal life with cells from a donor A becomes completely tolerant of homografts transplanted in later life from a donor B if, and only if, B contains no antigens that are not also present in A. (In practice, this condition is most easily fulfilled when A and B are members of the same highly inbred strain.) The reaction of a tolerant animal against a homograft from an unrelated donor is not perceptibly impaired. Tolerance does not, however, discriminate between the tissues of a single individual; the inoculation of foetal or newborn mice with leucocytes or with the cells of a mammary carcinoma may confer tolerance of later homografts of skin (sections 4.2, 9). Tolerance of a homograft is neither caused by nor accompanied by an antigenic adaptation of the grafted cells. An animal that is tolerant of a homograft in one part of its body is tolerant in another; tolerance is systemic, and a tolerated graft does not build up a privileged position within its own lymphatic territory (section 4.3). Every degree of tolerance is possible, from that which allows a homograft to live only a few days beyond its normal median expectation of survival to that in which it is permanently accepted by and incorporated into its host. An inhibition of response which is partial may nevertheless be permanent, for the weakening of the 'secondary response' in partially tolerant animals is proportional to the weakening of the first (sections 3.2, 4.4). The stimulus which confers tolerance must be fully antigenic, i.e. must be one which would have caused an older animal to have become immune. Cells such as erythrocytes which have no power to elicit transplantation immunity are incapable of causing tolerance of tissue homografts; all treatments which abolish the power of cells to confer tolerance upon embryos will also abolish their power to make older animals immune (section 5). Immunological reactivity can be promptly and permanently restored to a tolerant animal by inoculating it with cells taken from the regional lymph nodes of actively immunized members of its inbred strain. It may also be restored, more slowly, by the inoculation of normal unimmunized lymph node cells. A tolerant mouse thus retains in full the power to give effect to an immunity of adoptive ('passive') origin; a tolerated homograft continues to be a source of antigenic stimuli, and its susceptibility to a reaction directed against it remains unchanged. Tolerance represents a central failure of the mechanism of the immunological reaction, and is not caused by an intercession at a peripheral level (section 6). The relationship between twinning, fertility, tolerance and red-cell chimerism is analyzed. Like dizygotic twin cattle, twin chicks that arise from double-yolked eggs are synchorial, are red-cell chimeras, and are tolerant of grafts of each other's skin. Tolerance and infertility are not causally connected. The tolerance produced in chicks by artificial synchorial parabiosis from the 10th day of embryonic life until hatching is accompanied by a true persistent red-cell chimerism. The disappearance of chimerism in partially tolerant chickens does not reveal a return to normal reactivity, for their secondary response to red cells reintroduced by cross-injection is profoundly impaired (section 7). Some measure of tolerance of skin heterografts may be achieved by the synchorial union of embryonic ducks and chicks (section 8). Tolerance may be produced by, and in respect of, tumour homografts, and by tumour homografts in respect of skin. A degree of immunity which does not suffice to hold in check the growth of a tumour may destroy a normal homograft completely; the growth of a tumour homograft is therefore a less exacting measure of tolerance than the survival time of a homograft of skin (section 9). A naturally acquired tolerance of maternal homografts is believed to occur, very rarely, in guineapigs, presumably by the accidental incorporation into a foetus of maternal cells. No such natural tolerance has been observed in mice or rabbits (section 10). Phenomena cognate with tolerance are considered. The partial inhibition of transplantation immunity which is caused by injecting adult animals with variously modified antigenic matter differs fundamentally from tolerance in mode of origin, for the substances which enhance the growth of homografts after administration to older animals have no power to confer tolerance upon embryos, and the substances which cause embryos to become tolerant merely cause adults to become immune (section 11.1). It is argued that the iso-antigens responsible for transplantation immunity should be sharply distinguished from those specialized end-products of differentiation which are iso-antigenic because they are potentially auto-antigenic, and which are potentially auto-antigenic because the antibody-forming system has no opportunity in normal development to become tolerant of their action (section 11.2). The phenomenon of tolerance is considered for its bearing upon the relationship between mammalian mother and foetus; upon the different stages of development at which immunity to different antigens may arise; upon the antigenic and genetic composition of the different tissues of a single individual; and upon the fate of iso-antigens in normal life (section 11.3).

The physiological and behavioral effects of radio music on singly housed baboons

The response of four singly caged baboons to radio music was measured using behavioral and physiological indices. Heart rate and blood pressure, measured through a tether system, as well as behavior, were recorded during a two-week period in which radio music was available in half of the samples. The behavior of the subjects, as well as their blood pressure, did not vary in relation to radio music. Heart rate was significantly lower when the radio was on.

Evaluation of the chimpanzee breeding program at the Southwest Foundation for Biomedical Research

The history of the chimpanzee (Pan troglodytes) breeding colony of the Southwest Foundation for Biomedical Research was evaluated over a 24-year period to determine age at conception, breeder rearing history, maternal competence, and infant rearing history. The records of 107 breeders and 268 live births were reviewed. Of the breeders with known rearing histories, 40 were wild-born (12 male and 28 female), 16 were reared by their mothers for at least 1 month (8 male and 8 female), and 13 were removed from their mothers immediately after birth (2 males and 11 females). The age of successful mating for males ranged from 7 to 32 years and for females from 7 to 41 years, although the upper limit indicates the age of the population and not reproductive senescence. The mother's rearing history was related to her maternal competence, defined as caring for an infant for at least 1 month. Of the wild-born females, 82% (18/22) were competent mothers. For females that had been reared in captivity with their mothers for 1 to 12 months, 71% (5/7) were competent. For females that had been removed from their mothers immediately and reared in a nursery by humans, only 14% (1/7) were competent. The rearing strategies have changed during the period under consideration. The number of infants reared by their mothers increased in the 1980s, while the number of infants removed from their mothers immediately for experimental reasons decreased and dropped to zero in the 1990s. Information on the history of the breeding colony has been used to make management decisions and to determine the expectations of the Southwest Foundation chimpanzee breeding program.

Self-recognition and abstraction abilities in the common chimpanzee studied with distorting mirrors

The reactions of chimpanzees to regular mirrors and the results of the standard Gallup mark test have been well documented. In addition to using the mark test to demonstrate self-recognition in a regular mirror, we exposed six female chimpanzees to mirrors that produced distorted or multiplied self-images. Their reactions to their self-images, in terms of mirror-guided self-referenced behaviors, indicated that correct assessment of the source of the mirror image was made by each subject in each of the mirrors. Recognition of a distorted self-image implies an ability for abstraction in the subjects in that the distortion must be rationalized before self-recognition occurs. The implications of these results in terms of illuminating the relative importance of feature and contingency of movement cues to self-recognition are discussed.

Long-term use of televisions, balls, and mirrors as enrichment for paired and singly caged chimpanzees

The evaluation of environmental enrichment techniques for nonhuman primates over long periods of time has had mixed results. Some studies report rapid habituation to new enrichment items, while others note continued use. We have investigated the use of three different enrichments that had been available to paired and singly caged chimpanzees for several years. Twenty subjects were observed during 200 hr of scan sampling while singly caged and while pair housed. Each subject had a variety of enrichments available and their use of a television, ball, and mirror were recorded. The chimpanzees had previous exposure to all of the items: televisions had been available for a mean of 22.75 months, balls had been available for 55.9 months, and mirrors had been available for 25.9 months. The results indicated that the chimpanzees continued to use the enrichments for small amounts of time (0.27%-1.53% of the observations) even after such prolonged exposure. Television and ball use were significantly higher than mirror use. Housing condition was not a significant factor in the analyses, contrary to expectations. We concluded that several simple enrichment items may be effective in offering variety and choices to the nonhuman primate and can be one element in a comprehensive environmental enhancement plan. © 1996 Wiley-Liss, Inc.

Feeding enrichment and body weight in captive chimpanzees

Although positive behavioral consequences have been attributed to feeding enrichment, physiological changes may also occur. In this study, the body weight records of a large chimpanzee colony were reviewed to determine if body weight was affected by the implementation of a daily enrichment program, including food items offered three to four times per week. Comparing the mean body weight by age groups indicated that the weight of female chimpanzees was significantly greater after feeding enrichment but that male body weight did not differ.

Social factors influencing performance of a foraging task for captive chimpanzees

The performance of captive chimpanzees (Pan troglodytes) during a simulated foraging activity was compared to that reported for the foraging behavior of wild chimpanzees. The ability to find hidden fruit in a large outdoor play area was measured for 34 subjects housed in ten separate groups. Sex differences were apparent, with females searching for and finding significantly more fruit than males did. Chimpanzees of high and medium dominance rank found more fruit than those of low rank. Neither age nor stage of the female sexual cycle exerted an influence. The subjects became more proficient at finding fruit during the second block of trials. The results reflect possible influences of captivity on chimpanzee social behavior.

Is epidermal cell proliferation in psoriatic skin grafts on nude mice driven by T-cell derived cytokines?

Plasminogen activity and DNA synthesis by epidermal cells have been reported to be doubled in psoriatic skin grafts compared with grafts of normal skin 6 weeks after transplantation to nude mice. In our study human lymphocytes disappeared from such grafts within 48 h whilst some DR-positive human dendritic cells were retained in the grafts for up to 4 weeks. However, the grafts were infiltrated by Thy 1.2+ mouse lymphocytes within 6 days and this infiltration persisted at a moderate level throughout the observation period. It consisted of perivascular aggregates, scattered dermal and papillary T cells, and some mouse T cells were also found in the epidermal compartment. Grafts of psoriatic and non-psoriatic control skin were infiltrated to a similar extent, suggesting a low-grade rejection response against the human xenografts. These findings raise the possibility that psoriatic keratinocytes are responding abnormally to inflammatory cytokines released by mouse lymphocytes reacting against the skin grafts.