Obesity Measures and Definitions of Sarcopenic Obesity in Singaporean Adults - the Yishun Study.

OBJECTIVES: Due to the lack of a uniform obesity definition, there is marked variability in reported sarcopenic obesity (SO) prevalence and associated health outcomes. We compare the association of SO with physical function using current Asian Working Group for Sarcopenia (AWGS) guidelines and different obesity measures to propose the most optimal SO diagnostic formulation according to functional impairment, and describe SO prevalence among community-dwelling young and old adults. DESIGN: Obesity was defined according to waist circumference (WC), percentage body fat (PBF), fat mass index (FMI), fat mass/fat-free mass ratio (FM/FFM), or body mass index (BMI). SO was defined as the presence of both obesity and AWGS sarcopenia. Muscle function was compared among phenotypes and obesity definitions using ANOVA. Differences across obesity measures were further ascertained using multiple linear regressions to determine their associations with the Short Physical Performance Battery (SPPB). SETTING: Community-dwelling adults 21 years old and above were recruited from a large urban residential town in Singapore. PARTICIPANTS: 535 community-dwelling Singaporeans were recruited (21-90 years old, 57.9% women), filling quotas of 20-40 participants in each sex- and age-group. MEASUREMENTS: We took measurements of height, weight, BMI, waist and hip circumferences, body fat, muscle mass, muscle strength, and functional assessments. Questionnaire-based physical and cognitive factors were also assessed. RESULTS: Overall prevalence of SO was 7.6% (WC-based), 5.1% (PBF-based), 2.7% (FMI-based), 1.5% (FM/FFM-based), and 0.4% (BMI-based). SO was significantly associated with SPPB only in the FMI model (p<0.05), and total variance explained by the different regression models was highest for the FMI model. CONCLUSIONS: Our findings suggest FMI as the most preferred measure for obesity and support its use as a diagnostic criteria for SO.

Development, Validation and Field Evaluation of the Singapore Longitudinal Ageing Study (SLAS) Risk Index for Prediction of Mild Cognitive Impairment and Dementia.

BACKGROUND: Mild cognitive impairment (MCI) is a critical pre-dementia target for preventive interventions. There are few brief screening tools based on self-reported personal lifestyle and health-related information for predicting MCI that have been validated for their generalizability and utility in primary care and community settings. OBJECTIVE: To develop and validate a MCI risk prediction index, and evaluate its field application in a pilot community intervention trial project. DESIGN: Two independent population-based cohorts in the Singapore Longitudinal Ageing Study (SLAS). We used SLAS1 as a development cohort to construct the risk assessment instrument, and SLA2 as a validation cohort to verify its generalizability. SETTING: community-based screening and lifestyle intervention Participants: (1) SLAS1 cognitively normal (CN) aged ≥55 years with average 3 years (N=1601); (2) SLAS2 cohort (N=3051) with average 4 years of follow up. (3) 437 participants in a pilot community intervention project. MEASUREMENTS: The risk index indicators included age, female sex, years of schooling, hearing loss, depression, life satisfaction, number of cardio-metabolic risk factors (wide waist circumference, pre-diabetes or diabetes, hypertension, dyslipidemia). Weighted summed scores predicted probabilities of MCI or dementia. A self-administered questionnaire field version of the risk index was deployed in the pilot community project and evaluated using pre-intervention baseline cognitive function of participants. RESULTS: Risk scores were associated with increasing probabilities of progression to MCI-or-dementia in the development cohort (AUC=0.73) and with increased prevalence and incidence of MCI-or-dementia in the validation cohort (AUC=0.74). The field questionnaire risk index identified high risk individuals with strong correlation with RBANS cognitive scores in the community program (p<0.001). CONCLUSIONS: The SLAS risk index is accurate and replicable in predicting MCI, and is applicable in community interventions for dementia prevention.

Malnutrition and Sarcopenia in Community-Dwelling Adults in Singapore: Yishun Health Study.

OBJECTIVES: To determine the overlapping prevalence of malnutrition and sarcopenia and the association between parameters of malnutrition with muscle mass and strength in a community-dwelling Singaporean adult population. DESIGN: This was a cross-sectional study. SETTING: Large north-eastern residential town of Yishun in Singapore. PARTICIPANTS: Random sampling of community-dwelling Singaporeans aged 21-90 years old (n=541). MEASUREMENTS: Anthropometry, body composition and handgrip strength (muscle strength) were measured. Sarcopenia was identified using dual-energy x-ray absorptiometry scan (muscle mass). Nutritional status was measured using Mini Nutritional Assessment (MNA-SF). Other questionnaires collected included physical activity and cognition. Associations between nutritional status with sarcopenia as well as with muscle mass and strength were analysed using multinomial logistics and linear regressions. RESULTS: The overall population-adjusted prevalence of those at nutritional risk and malnourished were 18.5% and 0.1% respectively. More than a third of participants (35%) who were at nutritional risk were sarcopenic. Malnourished participants were all sarcopenic (100%, N=2) whereas those who were sarcopenic, 27.0% (N=37) were at nutritional risk/malnourished. Being at nutritional risk/malnourished was significantly associated with 2 to 3 times increased odds of sarcopenia in multivariate analyses adjusting for age, gender, physical activity level and cognition, and fat mass index. Favourable MNA parameter scores on food intake and BMI were positively associated with greater muscle mass and handgrip strength (p<0.05). CONCLUSION: Given the overlapping clinical presentation of malnutrition and sarcopenia, community screening protocols should include combination screening of nutritional status and sarcopenia with appropriate interventions to mitigate risk of adverse health outcomes.

Interictal hemodynamic abnormality during motor activation in sporadic hemiplegic migraine: An explorative study.

INTRODUCTION: The motor weakness in sporadic hemiplegic migraine (SHM) is a poorly understood aura manifestation. Cortical spreading depression affecting motor excitability and alterations of neurovascular coupling may be integral to the development of migraine aura. METHODS: We studied 10 right-handed SHM patients and 17 healthy controls with functional near-infrared spectroscopy (fNIRS) in the interictal period. Subjects performed a finger opposition task and had real time determination of oxyhemoglobin (OxyHb) and deoxyhemoglobin (deOxyHb) changes. Recordings were completed with 10 left and 10 right sided cortical channels. RESULTS: Mean baseline to peak changes were significantly reduced in SHM patients as compared to controls bilaterally only for OxyHb measurements in the anteromedial channels. Mean time to peak changes were significant delayed in SHM patients compared to controls bilaterally largely for OxyHb measurements in the posterolateral channels, with the exception of 2 recording channels. CONCLUSIONS: Our findings suggest presence of abnormal interictal hemodynamic responses to increased metabolic demands during motor activation in SHM. These bilateral cerebrovascular changes involve OxyHb to a much larger degree than deOxyHb. Baseline to peak changes were evident more in the anteromedial channels, whereas time to peak changes were more evident in the posterolateral channels. These findings suggest that oxygen inflow into specific brain regions may be defective in SHM as opposed to oxygen utilization. Our findings suggest that in SHM, enduring hemodynamic deficits in response to an impending motor task are evident, which can be further explored in future studies, and possibly therapeutic trials.

Risk Factors of Progression to Frailty: Findings from the Singapore Longitudinal Ageing Study.

OBJECTIVES: To investigate risk factors of incident physical frailty. DESIGN: A population-based observational longitudinal study. SETTING: Community-dwelling elderly with age 55 years and above recruited from 2009 through 2011 in the second wave Singapore Longitudinal Ageing Study-2 (SLAS-2) were followed up 3-5 years later. PARTICIPANTS: A total of 1297 participants, mean age of 65.6 ±0.19, who were free of physical frailty. MEASUREMENTS: Incident frailty defined by three or more criteria of the physical phenotype used in the Cardiovascular Health Study was determined at follow-up. Potential risk factors assessed at baseline included demographic, socioeconomic, medical, psychological factors, and biochemical markers. RESULTS: A total of 204 (15.7%) participants, including 81 (10.87%) of the robust and 123 (22.28%) of the prefrail transited to frailty at follow-up. Age, no education, MMSE score, diabetes, prediabetes and diabetes, arthritis, ≥5 medications, fair and poor self-rated health, moderate to high nutritional risk (NSI ≥3), Hb (g/dL), CRP (mg/L), low B12, low folate, albumin (g/L), low total cholesterol, adjusted for sex, age and education, were significantly associated (p<0.05) with incident frailty. In stepwise selection models, age (year) (OR=1.07, 95%CI=1.03-1.10, p<0.001), albumin (g/L) (OR=0.85, 95%CI=0.77-0.94, p=0.002), MMSE score (OR=0.88, 95%CI=0.78-0.98, p=0.02), low folate (OR=3.72, 95%CI=1.17-11.86, p=0.03, and previous hospitalization (OR=2.26, 95%CI=1.01-5.04,p=0.05) were significantly associated with incident frailty. CONCLUSIONS: The study revealed multiple modifiable risk factors, especially related to poor nutrition, for which preventive measures and early management could potentially halt or delay the development of frailty.

The Changing Profile of Patients in a Geriatric Medicine Led Memory Clinic over 12 Years.

OBJECTIVES: Memory clinics play an important role in enabling early dementia diagnosis and intervention. Few studies have investigated the changing patient profiles at memory clinics over time. We studied the trend of patient characteristics in a geriatric medicine-led memory clinic over 12 years to improve services and care to meet their needs. SETTING AND PARTICIPANTS: Data from 2340 first-visit patients seen at a memory clinic from 2005-2017 were extracted from a registered database and analysed. DESIGN: ANOVA, Pearson chi-square and non-parametric tests were used to describe and compare between patients with dementia (PWD) and patients with no dementia (PND). MEASUREMENTS: Data included diagnoses of dementia and mild cognitive impairment, age, education, MMSE scores and comorbidities. RESULTS: Patients averaged 77.2 ± 8.3 years of age with mean MMSE score of 16.2 ± 6.7. Those diagnosed with dementia were older (78.3 ± 7.9 years) and almost half (48.4%) had moderate or moderately severe dementia (FAST 5-6). Over time, there was a growing proportion of patients with mild cognitive impairment (MCI) and mild Alzheimer's dementia. Many PWD had co-morbidities of hypertension (65.9%), hyperlipidemia (55.1%), diabetes (33.5%) and 28.4% were frail. CONCLUSIONS: The findings call for services to better diagnose and manage patients at the earlier stages of cognitive impairment and provide holistic interventions for those with frailty and other co-morbidities. The continued rise in number of patients presenting to memory clinics provides impetus to expedite integration of tertiary-based memory clinics with primary and community care providers to better support PWD and their families.

Nutritional and Frailty State Transitions in the Singapore Longitudinal Aging Study.

BACKGROUND: Malnutrition is a major determinant of the physical frailty syndrome. Dynamic transitions in frailty states over time is well documented, but few studies have documented temporal changes in nutritional states and whether they influence frailty outcomes. DESIGN: Longitudinal cohort study. SETTING AND PARTICIPANTS: Community-dwelling older Singaporeans aged ≥55y with a 5-year follow-up (n=1162) in the Singapore Longitudinal Ageing Study 2 (SLAS-2). MEASUREMENTS: The Mini Nutritional Assessment Short-Form (MNA-SF) was used to determine nutritional status, and the Fried's criteria (shrinking, weakness, slowness, exhaustion and inactivity) was used to assess physical frailty phenotype at both baseline and follow-up. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were adjusted for multiple baseline co-variables. RESULTS: At baseline, being at risk of malnutrition/malnourished was associated with increased odds of prevalent pre-frailty (OR=2.76, 95% CI=1.86-4.10) and frailty (OR=4.10, 95% CI=1.41-11.9). Baseline robust individuals who were persistently at risk of malnutrition/malnourished showed an increased odds of conversion to being pre-frail/frail at follow-up (OR=3.45, 95% CI=1.00-11.9). Among baseline pre-frail/frail individuals, reversion to being robust were significantly less likely among those who were persistently at risk of malnutrition/malnourished (OR=0.26, 95% CI=0.10-0.67) and those whose baseline normal nutrition worsened at follow-up (OR=0.20, 95% CI=0.06-0.74). CONCLUSION: Changes in nutritional states are associated with frailty state transitions, and monitoring changes in nutritional status is recommended for the prevention and severity reduction of frailty among older people in the community.

Sex modulates the association of fibroblast growth factor 21 with end-stage renal disease in Asian people with Type 2 diabetes: a 6.3-year prospective cohort study.

AIM: To study whether plasma fibroblast growth factor 21 independently predicts the risk of end-stage renal disease in Asian people with Type 2 diabetes. METHODS: In this prospective cohort study, 1700 Asian people with Type 2 diabetes were followed for a mean of 6.3 years in a regional hospital in Singapore. Incident end-stage renal disease was identified by linkage with a national renal registry. The association of baseline fibroblast growth factor 21 levels with risk of progression to end-stage renal disease was studied using survival analyses. RESULTS: Participants were aged 60 ± 10 years, with an average diabetes duration of 12 years. Their estimated GFR was 73 ± 28 ml/min/1.73 m2 and 62% had albuminuria at baseline. A total of 179 incident end-stage renal disease cases were identified. Plasma fibroblast growth factor 21 interacted with sex in its association with end-stage renal disease (Pinteraction = 0.003). A 1-sd increment in fibroblast growth factor 21 (natural log-transformed) was associated with a 1.32-fold (95% CI 1.05-1.66, P = 0.02) increased hazard for end-stage renal disease in women, after adjustment for traditional risk factors including estimated GFR and albuminuria. Taking death as a competing risk did not materially change the outcome [sub-distribution hazard ratio 1.35 (95% CI 1.11-1.66, P = 0.003)]. Fibroblast growth factor 21 did not predict end-stage renal disease risk in men after adjustment for baseline estimated GFR and albuminuria [hazard ratio 1.07 (95% CI 0.89-1.28, P = 0.49)]. CONCLUSIONS: Plasma fibroblast growth factor 21 level independently predicted risk of progression to end-stage renal disease in women with Type 2 diabetes. The pathophysiological relationships among FGF21, sex and renal progression warrant further study.

Strong Relationship between Malnutrition and Cognitive Frailty in the Singapore Longitudinal Ageing Studies (SLAS-1 and SLAS-2).

BACKGROUND: Physical frailty is well known to be strongly associated with malnutrition, but the combined impact of physical frailty and cognitive impairment among non-demented older persons (cognitive frailty) on malnutrition prevalence is not well documented. DESIGN: Cross-sectional cohort study. SETTING AND PARTICIPANTS: Community-dwelling older Singaporeans aged ≥55y (n=5414) without dementia in the Singapore Longitudinal Ageing Study (SLAS-1 and SLAS-2). MEASUREMENTS: The Mini Nutritional Assessment - short form (MNA-SF) and Nutrition Screening Initiative (NSI) Determine Checklist were used to determine their nutritional status. Participants were categorized as cognitive normal (CN) or cognitive impaired (CI) by Mini Mental State Examination (MMSE<=23), as pre-frail (PF) (score=1-2) or frail (F) (score=3-5) using Fried's criteria, and as cognitive pre-frail (PF+CI) or cognitive frail (F+CI). RESULTS: The prevalence of cognitive frailty was 1.6%, and cognitive pre-frailty was 5.5% (total, 7.1%). The prevalence of MNA malnutrition was 2.4%, and NSI high nutritional risk was 6.3%. The prevalence of MNA malnutrition was lowest among Robust-CN and highest among Frail-CI (0.5% in Robust-CN, 0.6% in Robust-CI, 2.8% in Pre-frail-CN, 7.3% in Pre-frail-CI, 15.4% in Frail-CN, and 23.1% in Frail-CI). Similarly, the prevalence of NSI high nutritional risk was lowest in Robust-CN (3.7%) and highest in Frail-CI (13.6%). Adjusted for sociodemographic and health status, pre-frailty/frailty-CI versus Robust-CN was associated with the highest odds ratio of association with MNA malnutrition (OR=8.16, p<0.001), although not the highest with NSI high nutritional risk (OR=1.48, p=0.017). CONCLUSIONS: An extraordinary high prevalence of malnutrition was observed among older adults with cognitive frailty who should be specially targeted for active intervention.

Attraction and consumption of methyl eugenol by male Bactrocera umbrosa Fabricius (Diptera: Tephritidae) promotes conspecific sexual communication and mating performance.

The Artocarpus fruit fly, Bactrocera umbrosa (Fabricius) (Diptera: Tephritidae), is an oligophagous fruit pest infesting Moraceae fruits, including jackfruit (Artocarpus heterophyllus Lamarck), a fruit commodity of high value in Malaysia. The scarcity of fundamental biological, physiological and ecological information on this pest, particularly in relation to behavioural response to phytochemical lures, which are instrumental to the success of many area-wide fruit fly control and management programmes, underpins the need for studies on this much-underrated pest. The positive response of B. umbrosa males to methyl eugenol (ME), a highly potent phytochemical lure, which attracts mainly males of many Bactrocera species, was shown to increase with increasing age. As early as 7 days after emergence (DAE), ca. 22% of males had responded to ME and over 50% by 10 DAE, despite no occurrence of matings (i.e. the males were still sexually immature). Male attraction to ME peaked from 10 to 27 DAE, which corresponded with the flies' attainment of sexual maturity. In wind-tunnel assays during the dusk courtship period, ME-fed males exhibited earlier calling activity and attracted a significantly higher percentage of virgin females compared with ME-deprived males. ME-fed males enjoyed a higher mating success than ME-deprived males at 1-day post ME feeding in semi-field assays. ME consumption also promotes aggregation behaviour in B. umbrosa males, as demonstrated in wind-tunnel and semi-field assays. We suggest that ME plays a prominent role in promoting sexual communication and enhancing mating performance of the Artocarpus fruit fly, a finding that is congruent with previous reports on the consequences of ME acquisition by other economically important Bactrocera species.

Morganella morganii bacteria produces phenol as the sex pheromone of the New Zealand grass grub from tyrosine in the colleterial gland.

Costelytra zealandica (Coleoptera: Scarabeidae) is a univoltine endemic species that has colonised and become a major pest of introduced clover and ryegrass pastures that form about half of the land area of New Zealand. Female beetles were previously shown to use phenol as their sex pheromone produced by symbiotic bacteria in the accessory or colleterial gland. In this study, production of phenol was confirmed from the female beetles, while bacteria were isolated from the gland and tested for attractiveness towards grass grub males in traps in the field. The phenol-producing bacterial taxon was identified by partial sequencing of the 16SrRNA gene, as Morganella morganii. We then tested the hypothesis that the phenol sex pheromone is biosynthesized from the amino acid tyrosine by the bacteria. This was shown to be correct, by addition of isotopically labelled tyrosine ((13)C) to the bacterial broth, followed by detection of the labelled phenol by SPME-GCMS. Elucidation of this pathway provides specific evidence how the phenol is produced as an insect sex pheromone by a mutualistic bacteria.

Identification and electrophysiological studies of (4S,5S)-5-hydroxy-4-methyl-3-heptanone and 4-methyl-3,5-heptanedione in male lucerne weevils.

An investigation to identify a sex or aggregation pheromone of Sitona discoideus Gyllenhål (Coleoptera: Curculionidae) is presented. Antenna flicking and attraction behaviors evoked by conspecifics of both sexes were recorded in arena bioassays, where attraction of females to males was observed. Air entrainment of both males and females was conducted in separate chambers. Gas chromatographic-mass spectrometric analysis of headspace volatiles revealed that two male-specific compounds, 4-methyl-3,5-heptanedione (major) and (4S,5S)-5-hydroxy-4-methyl-3-heptanone (minor), were emitted during the autumnal post-aestivatory flight period. The stereoisomers of the minor component were separated by enantioselective gas chromatography and their absolute configurations assigned by NMR (diastereomers) and the known preference of enantioselective transesterification reactions catalyzed by Candida antarctica lipase B. Electroantennogram and single sensillum recording studies indicate that 4-methyl-3,5-heptanedione as well as all individual stereoisomers of 5-hydroxy-4-methyl-3-heptanone are detected by the antennae of male and female S. discoideus. Further, single sensillum recordings suggest that both sexes of S. discoideus have specialized olfactory receptor neurons (ORNs) for detecting 4-methyl-3,5-heptanedione and different populations of stereoselective ORNs for detecting the stereoisomers of 5-hydroxy-4-methyl-3-heptanone. Some of these stereoselective ORNs appear to be sex-specific in S. discoideus.

Volatiles from apple trees infested with light brown apple moth larvae attract the parasitoid Dolichogenidia tasmanica.

The volatile compounds emitted from uninfested apple seedlings, cv. Royal Gala, and apple seedlings infested with generalist herbivore Epiphyas postvittana larvae were sampled using headspace collection and analyzed by gas chromatography-mass spectrometry. Nine additional compounds were only detected in infested apple seedlings [including benzyl alcohol, (E)-ß-ocimene, benzyl cyanide, indole, (E)-nerolidol, and four unidentified compounds]. Infested apple seedlings produced larger amounts of (Z)-3-hexenyl acetate, linalool, 4,8-dimethyl-1,3(E),7-nonatriene, methyl salicylate, ß-caryophyllene, germacrene D, (E,E)-α-farnesene, and (Z)-3-hexenyl benzoate than uninfested plants. Female parasitoids flew exclusively upwind to infested and not to uninfested apple seedlings in wind tunnel choice tests and preferred infested leaflets in still air, even after the removal of larvae. The attraction of a parasitoid to infested apple seedlings in the laboratory and in the field to apple and many other plants in at least six families supports considerable generality of the tritrophic signaling process.

Effects of substerilizing doses of gamma radiation on adult longevity and level of inherited sterility in Teia anartoides (Lepidoptera: Lymantriidae).

The effects of substerilizing doses of gamma radiation on the longevity and level of inherited sterility in the Australian moth Teia anartoides Walker were determined. Six day-old male pupae were treated with 0, 100, and 160 Gy of gamma radiation by using a 1.25 MeV Cobalt60 irradiation source. Laboratory studies of male longevity showed that radiation had little impact in adult moths of the P1, F1, and F2 generations. Inherited deleterious effects resulting from irradiation were observed in the progeny of F1 and F2 generations. Outcrosses between substerile parental males or their highly sterile male progeny to wild-type females did not affect female fecundity. However, adverse effects were observed for these crosses in the rates of successful egg hatch and postembryonic development. Fertility was always greater in out-crosses involving a P1 male than in any of the F1 out-crosses. F1 males were always more sterile than F1 females, and the level of sterility for the F1 and F2 generations was higher than that of the controls. The incidence of larval and pupal mortality was higher in the F2 than the F1 generation. A dose of 100 Gy had the highest success in inducing deleterious effects that were inherited through to the F2 generation. Our results indicated that the use of partially sterilizing doses of radiation has good potential as a selective strategy for management or eradication of T. anartoides.

Allomonal and hepatotoxic effects following methyl eugenol consumption in Bactrocera papayae male against Gekko monarchus.

Methyl eugenol (ME), is converted into two major phenylpropanoids, 2-allyl-4,5-dimethoxyphenol and trans-coniferyl alcohol, following consumption by the male fruit fly Bactrocera papayae. Chemical analysis of wild male B. papayae rectal glands, where the compounds are sequestered, revealed the presence of ME metabolites in varying quantities. These phenylpropanoids are shown to be involved in the fruit fly defense both in no-choice and choice feeding tests against the Malayan spiny gecko, Gekko monarchus. After being acclimatized to feeding on fruit flies, geckos consumed significantly fewer ME-fed male flies than controls that consumed all the ME-deprived male flies offered throughout a two-week period. Diagnosis of dissected livers from geckos that consumed ME-fed male flies revealed various abnormalities. These included discoloration and hardening of liver tissue, whitening of the gallbladder, or presence of tumor-like growths in all geckos that consumed ME-fed male flies. Control geckos fed on ME-deprived male flies had healthy livers. When given an alternative prey, geckos preferred to eat untreated house flies, Musca domestica to avoid preying on ME-fed fruit flies.

Long-term islet allograft function in the absence of chronic immunosuppression: a case report of a nonhuman primate previously made tolerant to a renal allograft from the same donor.

UNLABELLED: Development of mixed chimerism by donor bone marrow transplantation (DBMT) has led to long-term tolerance of solid organ allografts in nonhuman primates. As an initial attempt to extend this approach to cellular transplant, islet transplant from the same donor was attempted in the recipient previously made tolerant to a kidney allograft. METHODS: After the conditioning with ATG, total body irradiation, thymic irradiation, and splenectomy, DBMT was performed followed by 4 weeks of cyclosporine. Kidney transplantation and native nephrectomies were subsequently performed on day 89. After 2.8 years of DBMT, diabetes was induced by streptozocin (STZ) and islets from bone marrow and kidney donor were transplanted without immunosuppression. RESULTS: After DBMT, the recipient developed chimerism and no evidence of kidney rejection for more than 1000 days. STZ induced diabetes was reversed after the islet transplantation. Islet biopsies demonstrated insulin staining without rejection. Although the recipient became diabetic 300 days after islet transplantation, viable transplanted islets were found in the liver and under the kidney capsule without any evidence of rejection. CONCLUSION: Tolerance with a nonmyeloablative conditioning can allow successful pancreatic islet transplantation without immunosuppression. Because no histological evidence of rejection was identified, recurrent diabetes is presumed to be inadequate islet mass.

Association of natural killer cell depletion with induction of mixed chimerism and allograft tolerance in non-human primates.

BACKGROUND: Nonmyeloablative T cell depletion followed by donor bone marrow infusion has proved to be an effective approach to induction of mixed chimerism and tolerance of organ allografts in non-human primates. To help define the mechanisms involved we have compared T cell depletion with ATG versus anti-CD2 monoclonal antibody with respect to establishment of mixed chimerism and induction of tolerance. METHOD: Both nonmyeloablative regimens included low dose total body irradiation (1.5 Gy x 2), thymic irradiation (7 Gy), splenectomy and kidney plus donor bone marrow transplantation, followed by a 4-week posttransplant course of cyclosporine. In addition, the ATG group (13 recipients) received antithymocyte globulin, although the LOCD2b group (10 recipients) were treated with an anti-CD2 monoclonal antibody (LOCD2b). RESULTS: In the ATG group, 11 of 13 monkeys developed multilineage chimerism and 9 survived for more than 100 days without kidney allograft rejection. In contrast, 0/10 monkeys in the LOCD2b group developed chimerism, 5 died of infection and 5 suffered progressive rejection; only 1 recipient survived beyond 100 days. Sequential monitoring of peripheral blood mononuclear cells revealed greater T cell (CD3+) depletion in the LOCD2b-treated animals compared to those receiving ATG. However, NK cells (CD16+CD8+) were significantly more depleted in the ATG group and NK function remained abrogated longer after ATG than LOCD2b treatment (3 weeks vs. <5 days). CONCLUSION: Despite excellent T cell depletion by LoCD2b, ATG was more effective in inducing chimerism and tolerance. This difference correlated with anti-NK activity of the two reagents. These data suggest that NK cells may also resist engraftment of allogeneic bone marrow cells in this model.

Tolerance in a concordant nonhuman primate model.

BACKGROUND: We have previously demonstrated that induction of mixed lymphohematopoietic chimerism resulted in donor specific renal allograft tolerance without the need for chronic immunosuppression in nonhuman primates. Here we have tested whether tolerance can be similarly induced for baboon to cynomolgus renal xenografts. METHODS: After preconditioning with anti-thymocyte globulin (ATG), nonlethal total body irradiation, and thymic irradiation, cynomolgus monkeys underwent splenectomy, native nephrectomies, and baboon marrow and renal transplants. Postoperative cyclosporine was given for 28 days. RESULTS: In Group 1 (n=2, survival= 13, 14 days), both animals developed anti-donor immunoglobulin G, had biopsy findings consistent with humoral rejection, and showed rapidly progressive xenograft failure. In Group 2 (n=5, survival=1, 16, 33, 112, 190 days), 15-deoxyspergualine was added to the regimen (Day 0-13). In one long-term survivor, donor specific hyporesponsiveness was first observed (mixed lymphocyte culture [(MLR]) on Day 48. MLR reactivity returned on Day 64 together with the development of anti-donor antibody and subsequent xenograft failure on Day 112. Donor specific T-cell hyporesponsiveness was detected in the other long-term survivor for the first 133 days, after which a donor-specific skin xenograft was placed, (survival 24 days). Following the skin graft rejection, a rise in the MLR, development of anti-donor antibody and progressive rejection of the renal xenograft were observed. CONCLUSIONS: Antibody-mediated rejection seems to constitute the major difference between concordant xenografts and allografts. Addition of 15-deoxyspergualine for 2 weeks posttransplant extended concordant primate xenograft survival to 6 months without chronic immunosuppression. In contrast to the allogeneic model, renal transplant acceptance in this xenogeneic system was interrupted by placement of a donor-specific skin graft.