Predictors of rewarded caregiving for family caregivers of person with dementia: A longitudinal study

The purpose of this study was to explore variables associated with rewarded caregiving for family caregivers of persons living with dementia over a 2-year follow-up. This correlational longitudinal study was comprised of 200 family caregivers of persons living with dementia from neurological clinics of a medical center was conducted. Dichotomous scoring of the Rewards of Caregiving Scale of the Family Caregiving Inventory resulted in 61 (30.5%) caregivers being assigned to the well-rewarded group and 139 (69.5%) to the poorly reward group at baseline. Variables included characteristics of family caregivers and their care receivers and assessments with validated scales of caregivers' social support and dyadic relational variables of mutuality, preparedness, and balance. Analysis at baseline showed significant predictors of well-rewarded family caregivers were being an adult child of the care receiver, having a high perceived level mutuality and having a high perceived level of preparedness. These three variables remained as significant predictors at the 1- and 2-year follow-up. Caregivers with high levels of perceived mutuality and preparedness at 2-years were seven times more likely to perceive themselves as well-rewarded. Based on the findings, developing clinical interventions that focus on promoting mutuality and preparedness for family caregivers of persons with dementia could allow caregivers to perceive their role as rewarding. Attention should also be paid to the relationship between the caregiver and care receiver to enhance the family caregiver's feelings of mutuality and preparedness.

Comparison of the effectiveness of assisted turning mattresses and conventional air mattresses in relieving body pressure in different lying positions

Pressure ulcers are a common problem among individuals who, for medical reasons, must spend most of their day in bed. Manually turning a person's body is labor intensive and can easily cause occupational injuries. To compare the effectiveness of a new assisted turning mattress in pressure management with that of a conventional air mattress. This is a single-session crossover trial study. Twenty-four participants confined to bed were transferred onto the selected mattress (assisted turning or conventional air mattresses) in the selected position. Average interface pressures of bony prominences were measured after the participants laid on the mattress in different positions. After the data collection, they were transferred to the second mattress, and the process was repeated. Subjective feedback from participants and caregivers was also acquired immediately following a one-week trial period of assisted turning mattresses. The mean interface pressures were comparable for most body parts between two mattresses. Subjective feedback showed that assisted turning mattresses could relieve caregivers' workload but at the cost of patients' decreased feelings of safety. Assisted turning mattresses are equal to conventional air mattresses in pressure distribution. Proper pressure management through scheduled positional changes is required in assisted turning mattresses.

A community-based computerised cognitive training program for older persons with mild dementia: A pilot study

OBJECTIVES

Computerised cognitive training programs can improve cognitive function in patients with moderate-to-severe dementia or brain injuries and healthy older adults. However, most previous studies were not randomised controlled trials and did not examine older adults with mild dementia. The current study sought to analyse the effects of a computerised cognitive training program using a randomised controlled trial.

METHODS

In a single-blinded randomised clinical trial, 30 older individuals with mild dementia were split into an experimental (n = 15) and a control (n = 15) group to analyse the effects of a computerised cognitive training program. Outcomes were assessed before and after each program session, and 1 and 3 months afterwards.

RESULTS

Participants in the experimental group had better overall subjective memory, subjective retrospective memory and global quality of life, with fewer depressive symptoms than those in the control group 3 months following the program.

CONCLUSIONS

Our computerised cognitive training program improved subjective memory and quality of life in patients with mild dementia and decreased their depressive symptoms. These results may be useful for health-care providers caring for people with mild dementia.

Cognitive dysfunction predicts worse health-related quality of life for older stroke survivors: a nationwide population-based survey in Taiwan

OBJECTIVES

This study investigated the associations of cognitive status with specific/overall health-related quality of life (HRQoL) in older stroke survivors in Taiwan.

METHOD

A subsample of 592 older stroke survivors in a nationwide population-based survey of cognitive-dysfunction prevalencewas analyzed. HRQoL was assessed using the EuroQol five-dimension questionnaire (EQ-5D).

RESULTS

Stroke survivors with dementia were 5.60 times more likely to have mobility problems, 12.20 times to have self-care problems, 16.61 times to have problems in usual activities, 4.31 times to have pain/discomfort, and 3.28 times to have anxiety/depression than stroke survivors with normal cognitive function. Stroke survivors with mild cognitive dysfunction (MCD) were 2.57 times more likely to have mobility problems, 3.17 times to have self-care problems, 3.31 times to have problems in usual activities, 2.11 times to have pain/discomfort, and 2.35 times to have anxiety/depression than those with normal cognitive function. Both dementia (b = -15.13, p < .001) and MCD (b = -6.24, p < .001) significantly contributed to lower EQ-5D VAS; both dementia (b = -.15, p < .001) and MCD (b = -.10, p < .001) significantly contributed to lower EQ-5D index.

CONCLUSION

Dementia and MCD strongly predicted worse overall and specific HRQoL dimensions, especially self-care and usual activities for older stroke survivors.

[Introduction to Games for People With Dementia]

Dementia is typically classified into mild, moderate, and severe stages based on symptom severity. Prevention and early diagnosis is one of the care goals for dementia. Mild cognitive impairment (MCI) is a transitional stage between the cognitive changes of normal aging and dementia. Initiating an appropriate treatment regimen and methods at a sufficiently early stage has been shown to be effective in postponing the onset of dementia. Previous studies have confirmed the effectiveness of non-pharmacological treatments in improving the cognitive functions, reducing the onset of the behavioral and psychological symptoms of dementia, and training the physical functions of daily living in patients diagnosed with MCI. Game therapy, in addition to reminiscence therapy, music therapy, cognitive training, cognitive stimulation, and aromatherapy, is one of these non-pharmacological treatments. Moreover, game therapy may be used as a tool to screen individuals for symptoms of dementia. Using easily accessible, user-friendly, and affordable games, patients with dementia and their caregivers may receive their therapy in a more relaxed and enjoyable manner. Patients and their caregivers who perceive a prescribed therapy as a game are expected to exhibit higher motivation to use, which should result in better treatment outcomes. This paper will introduce and compare several games for people with dementia, providing valuable information for caregivers and healthcare professionals who are responsible for caring for patients with dementia.

Nurses' confidence in providing and managing care for older persons with depressive symptoms or depression in long-term care facilities: A national survey

The prevalence of depressive symptoms among older residents in long-term care facilities (LTCFs) is high. Nurses are the main healthcare providers in LTCFs and also the persons responsible for detecting changes in residents' mental function and providing subsequent care. Therefore, it is necessary to understand nurses' knowledge, attitudes, and confidence regarding care for older residents with depressive symptoms or depression. This study aimed to understand nurses' level of knowledge of late-life depression, attitudes towards depression, and confidence levels in caring for older adults with depressive symptoms or depression in LTCFs. A cross-sectional descriptive and correlational research design was used. A nationwide self-report survey was conducted in 2016. Ultimately, 556 valid questionnaires were returned. The study found that LTCF nurses' knowledge about late-life depression was poor, and they also lacked confidence in managing and caring for older persons with depressive symptoms or depression, but nurses' attitudes towards depression were neutral or slightly positive. Moreover, nurses who had greater confidence in providing care for older persons with depression were those with more positive attitudes towards depression, a greater interest level in taking care of older adults with depression, less late-life depression knowledge, longer nursing experience in LTCFs, and a greater interest level in late-life depression issues, and who had read late-life depression pamphlets or taken courses or classes in late-life depression. The findings suggest an urgent need to develop strategies to improve nurses' late-life depression knowledge and increase their confidence in providing care to older residents with depressive symptoms or depression.

Trajectories of Nutritional Status and Cognitive Impairment among Older Taiwanese with Hip Fracture

OBJECTIVE

This paper describes the trajectories of nutritional status and cognitive impairment and their correlation among older Taiwanese over 1 year after hip-fracture surgery.

DESIGN

Secondary analysis of data from a clinical trial evaluating the effects of three types of post-discharge care for 292 older hip-fracture patients (age >60 years).

MEASUREMENTS

Nutritional status was assessed by the Mini Nutritional Assessment before and 1, 3, 6, 12 months after hospital discharge. Cognitive function was measured by the Mini-Mental State Examination before surgery, at hospital discharge, 6 and 12 months after discharge. Trajectories of nutritional status and cognitive impairment were depicted by latent class growth modeling, whereas linkages between nutritional-status and cognitive-impairment trajectories were assessed by multinomial logistic regression.

RESULTS

Nutritional status in general improved significantly, particularly during the first 3 months after discharge. We identified three trajectories of nutritional status: malnourished (15.4%), at risk for malnutrition (38.9%), and well-nourished (45.7%). In contrast, cognitive changes followed four largely linear but distinct trajectories: moderately impaired (12.2%), mildly impaired (27.8%), borderline impaired (21.8%), and cognitively intact (38.2%). Trajectories of nutritional status were significantly associated with cognitive-function trajectories. For instance, relative to malnourished patients, well-nourished patients were 95% less likely (OR=0.05, CI =0.01-0.24) to be moderately cognitively impaired.

CONCLUSION

A good nutritional-status trajectory after hip fracture was associated with better cognitive function. To treat and care for elderly hip-fractured patients, specific interventions need to target those who are malnourished or at risk of malnutrition to decrease their risk for cognitive impairment.

A randomized controlled trial of a home-based training programme to decrease depression in family caregivers of persons with dementia

AIMS

The aim of this study was to explore distinct trajectories of caregivers' depressive symptoms and the effects of a training programme on these trajectories over 18 months after the programme.

BACKGROUND

Overall effects of caregiver-training programmes on family caregivers' depressive symptoms have been reported, but few studies explored distinct courses of changes in caregivers' depressive symptoms and followed up intervention effects on these distinct courses.

DESIGN

Randomized clinical trial.

METHODS

Family caregivers (n = 116) were randomly assigned into experimental (n = 57) and control (n = 59) groups. The experimental group received the training programme with telephone consultation and the control group received written educational materials and social telephone follow-ups. Caregivers' depressive symptoms were assessed from June 2009 - March 2012 by self-completed questionnaires before, at 2 weeks and 3, 6, 12 and 18 months after the intervention. Groups of individual trajectories were distinguished using group-based trajectory modelling.

RESULTS

Caregivers' depressive symptoms fell into three stable trajectories: non-depressed, mildly blue and depressed. After controlling for covariates, caregivers who received the caregiver-training programme were less likely than those who did not experience persistent depressive symptoms (b = -1·92, odds ratio = 0·15, P < 0·05).

CONCLUSION

Depressive symptoms of family caregivers of persons with dementia were relatively stable and followed three distinct courses: non-depressed, mildly blue and depressed. Therefore, caregivers' depressive symptoms should be assessed as early as possible. Caregivers in the experimental group had a lower probability of persistent depressive symptoms than caregivers in the control group. Therefore, this training programme can be used by healthcare providers for persons with dementia and their caregivers.

TRIAL REGISTRATION NUMBER

NCT02667951.

Health-related quality of life and self-efficacy of managing behavior problems for family caregivers of vascular dementia and Alzheimer's disease patients

BACKGROUND

Little is known about the differences in patients' behavioral problems and health outcomes of family caregivers of patients with vascular dementia (VaD) and Alzheimer's disease (AD).

METHODS

A secondary analysis of baseline data on a subsample of caregiver-dementia patient dyads in a randomized clinical trial.

RESULTS

Family caregivers of VaD patients reported higher self-efficacy than caregivers of AD patients in handling verbally nonaggressive and verbally aggressive behaviors. Caregivers of VaD patients had poorer health-related quality of life (HRQoL) than caregivers of AD patients considering role disability due to physical health problems, bodily pain, social function, and physical component summary. Greater self-efficacy was associated with better mental health-related outcomes for family caregivers of VaD patients, and better self-care ability of VaD patients was associated with better caregiver mental health-related outcomes. Caring for a patient with more severe dementia predicted poor physical health-related outcomes in role disability due to physical health problems, but better overall mental health (mental component summary) for caregivers.

CONCLUSION

This study is the first to examine and compare the behavioral problems of AD and VaD patients in a Chinese population, along with their family caregivers' self-efficacy and health outcomes. Family caregivers of patients with VaD might warrant specific attention to their HRQoL, with interventions developed to enhance their self-efficacy.

A home-based training program improves caregivers' skills and dementia patients' aggressive behaviors: a randomized controlled trial

OBJECTIVE

To investigate the effects of an individualized, home-based caregiver-training program for caregivers of elderly patients with dementia and behavioral problems.

METHODS

Using a randomized clinical trial in the neurologic clinics of two hospitals and a community care management center in northern Taiwan, we tested an individualized home-based caregiver-training program for managing behavioral problems, with referrals to community services and telephone consultation. Participants were patients with dementia and their caregivers (N = 129): 63 in the intervention group and 66 in the control group. The control group received only written instructions and social telephone follow-ups. Behavioral problems of elderly dementia patients were assessed by the Chinese version of the Cohen-Mansfield Agitation Inventory, community form. Family caregivers' outcomes were measured by the Agitation Management Self-efficacy Scale and the Preparedness and Competence Scales. These instruments were administered before the program and 2 weeks, 3 months, and 6 months afterward.

RESULTS

Family caregivers who received the individualized home-based training program had better preparedness (t = 2.72, df = 127, p <0.01), competence (t = 4.77, df = 126, p <0.001), and overall self-efficacy (t = 3.81, df = 127, p <0.001) at 3 months than those in the control group. Moreover, the growth rate by treatment interaction effect was significant for caregiver competence (t = 2.25, df = 127, p <0.05) and overall self-efficacy for managing behavioral problems (t = 2.16, df = 127, p <0.05). The probability of physically aggressive behavior for patients in the intervention group decreased from 0.27 to 0.12.

CONCLUSION

Our individualized home-based caregiver-training program improved caregivers' preparedness, competence, and self-efficacy for managing problematic behaviors and decreased physical aggressiveness of elderly patients with dementia.

A home-based training program improves Taiwanese family caregivers' quality of life and decreases their risk for depression: a randomized controlled trial

OBJECTIVES

Little is known about the longitudinal effects of training programs on family caregivers' health-related quality of life (HRQoL) and depressive symptoms over time. Therefore, the purpose of this study was to examine the effects of a home-based caregiver training program on HRQoL and depressive symptoms for family caregivers of older persons with dementia.

METHODS

Outcomes (caregivers' HRQoL and depressive symptoms) were assessed before the training program (baseline), and at 2 weeks, 3 months, and 6 months afterwards. HRQoL was measured using the Medical Outcomes Study 36-item Short Form Survey, Taiwan version. Depressive symptoms were measured using the Chinese version Center for Epidemiologic Studies Depression Scale.

RESULTS

Family caregivers who received the individualized home-based training program had better health outcomes in bodily pain (b = 12.37, p < 0.013), role disability due to emotional problems (b = 17.74, p < 0.013), vitality (b = 12.40, p < 0.001), better mental summary score (b = 5.14, p < 0.003), and decreased risk for depression (odds ratio = 0.15, confidence interval = 0.04-0.65, p < 0.013) than those in the control group during the 6 months following the training program.

CONCLUSION

Our home-based caregiver training program improved caregivers' HRQoL, especially role limitations due to emotional problems, and decreased their risk for depression.

A clinical trial of an individualised intervention programme for family caregivers of older stroke victims in Taiwan

AIM AND OBJECTIVE

To explore the long-term effects of a discharge-preparation programme targeting Taiwanese family caregivers of older patients with stroke.

BACKGROUND

Little is known about the effects of interventions for caregivers of patients with stroke in Asian and Chinese families.

DESIGN

A randomised experimental design was used.

METHOD

Participants included 158 older patients with stroke (72 in the experimental group and 86 in the control group) and their family caregivers. A caregiver-oriented intervention programme was designed to increase caregiver preparedness, to enhance caregiver perception of balance between competing needs and to satisfy specific needs during the transition between hospitalisation and discharge. Long-term outcomes were measured by caregiver's health-related quality of life, quality of care, stroke patient's self-care ability, patient's health-related quality of life and service utilisation. Longitudinal data were analysed by the generalised estimating equation approach.

RESULTS

During the 12 months following discharge of older patients with stroke, caregivers in the experimental group provided significantly better quality of care (beta = 0.45; p = 0.03) than the control group. Between the sixth-twelfth months following discharge, patients in the control group were more likely to be institutionalised than those in the experimental group (chi(2) = 5.11; p = 0.03).

CONCLUSION

Using a sample from Taiwan, this intervention programme succeeded in improving quality of care provided by family caregivers to older patients with stroke and in decreasing the likelihood of their institutionalisation.

RELEVANCE TO CLINICAL PRACTICE

Older Chinese patients with stroke and their family caregivers can benefit from an individualised programme that prepares caregivers for patient discharge. Similar programmes may be applicable to other countries with Chinese populations.

Process of ambivalent normalisation: experience of family caregivers of elders with mild cognitive impairment in Taiwan

AIMS AND OBJECTIVES

To conceptualise the caregiving process in Taiwanese families caring for elders with mild cognitive impairment.

BACKGROUND

Family caregivers play an essential role in the lives of elders with mild cognitive impairment by dealing with their cognitive status and daily function. Little is known, however, about the development of the caregiving trajectory, particularly in Asian countries.

DESIGN AND METHODS

Grounded theory methodology was used. Data were collected via in-depth interviews with 10 family caregivers of patients with mild cognitive impairment and living at home in northern Taiwan. Data were analysed by constant comparative analysis.

RESULTS

The process most used by family caregivers to adjust to conflicts and changes in relationships with elders with mild cognitive impairment was 'ambivalent normalisation'. This dynamic process included three components: subtle changes, optimistic appraisal and ambivalent anticipation. Family caregivers who had developed this process were more likely to adopt multiple effective behavioural approaches to avoid conflict in their daily life and to begin outlining future caregiving tasks.

CONCLUSIONS

The process of ambivalent normalisation can sensitise healthcare providers to family caregivers' needs and provide a basis for developing frameworks for future substantive theory and possible future research.

RELEVANCE TO CLINICAL PRACTICE

This study's findings may help healthcare providers understand family caregivers' needs and effective patterns for taking care of elders with mild cognitive impairment. Interventions can be developed to facilitate family caregivers' awareness of the changes in their loved one in the initial stage of diagnosis and adopt multiple effective strategies to prevent conflicts in their lives. Healthcare providers can actively examine the cognitive function of older people in general outpatient departments, provide well-timed treatments and minimise caregiver burden.

[Nursing experience: a new elderly resident in a nursing home]

Demographic changes in the population mean that relocation from community settings to long-term care institutions will steadily increase among elderly adults. As part of a normal aging process, these adults will experience change in their adaptation abilities, especially among those who experience physical or psychological function impairment. In this case report, the author describes an elderly woman with osteoarthritis who had to severely restrict her daily activities. Her move into a nursing home caused problems in terms of self-esteem and adjusting to a new environment. After providing appropriate nursing management and support, the patient's functional ability and physical challenges improved to the point that she was able to return to her family home.

Antitumour and anti-AIDS triterpenes from Celastrus hindsii

Four new triterpene compounds, celasdin-A, celasdin-C, anti-AIDS celasdin-B and cytotoxic maytenfolone-A, were isolated from Celastrus hindsii. The structural determination of maytenfolone-A, celasdin-A, celasdin-B and celasdin-C, as well as the structure-activity relationships of these new compounds and derivatives, are discussed. Maytenfolone-A was further confirmed by X-ray studies. Biological evaluation showed that Maytenfolone-A demonstrated cytotoxicity against hepatoma (HEPA-2B, ED50 = 2.3 micrograms ml-1) and nasopharynx carcinoma (KB, ED50 = 3.8 micrograms ml-1). Celasdin-B was found to exhibit anti-HIV replication activity in H9 lymphocyte cells with an EC50 of 0.8 microgram ml-1).

Specific domains of beta-amyloid from Alzheimer plaque elicit neuron killing in human microglia

Alzheimer's disease (AD) is found to have striking brain inflammation characterized by clusters of reactive microglia that surround senile plaques. A recent study has shown that microglia placed in contact with isolated plaque fragments release neurotoxins. To explore further this process of immunoactivation in AD, we fractionated plaque proteins and tested for the ability to stimulate microglia. Three plaque-derived fractions, each containing full-length native A beta 1-40 or A beta 1-42 peptides, elicited neurotoxin release from microglia. Screening of various synthetic peptides (A beta 1-16, A beta 1-28, A beta 12-28, A beta 25-35, A beta 17-43, A beta 1-40, and A beta 1-42) confirmed that microglia killed neurons only after exposure to nanomolar concentrations of human A beta 1-40 or human A beta 1-42, whereas the rodent A beta 1-40 (5Arg-->Gly, 10Tyr-->Phe 13His-->Arg) was not active. These findings suggested that specific portions of human A beta were necessary for microglia-plaque interactions. When coupled to microspheres, N-terminal portions of human A beta (A beta 1-16, A beta 1-28, A beta 12-28) provided anchoring sites for microglial adherence whereas C-terminal regions did not. Although itself not toxic, the 10-16 domain of human A beta was necessary for both microglial binding and activation. Peptide blockade of microglia-plaque interactions that occur in AD might prevent the immune-driven injury to neurons.

Celahinine A, a new sesquiterpene pyridine alkaloid from Celastrus hindsii

A new sesquiterpene pyridine alkaloid, celahinine A [1], and the related known polyester celahin A, as well as the known cytotoxic sesquiterpene pyridine alkaloid emarginatine A [2], were isolated from Celastrus hindsii. The structure of 1 was determined by 2D nmr techniques and was also confirmed by spectral comparison with the related 2.

Structure-function relationships for the IL-2 receptor system. V. Structure-activity analysis of modified and truncated forms of the Tac receptor protein: site-specific mutagenesis of cysteine residues

IL-2R on activated lymphocytes contain the Tac protein. As part of an effort to characterize this molecule, we examined the structure-activity relationship for each of its 12 Cys residues. A preliminary map of intramolecular disulfide bonding was derived by analysis of cystine-linked enzymatic fragments of the Tac protein. The results indicated that disulfide bonds linked Cys-3 with Cys-147, Cys-131 with Cys-163, and Cys-28,30 with Cys-59,61. The contribution of the Cys residues to an active protein conformation was tested by site-specific mutagenesis, followed by expression of the modified molecules in murine L cells. The results indicated that Cys-192 and -225 could be replaced without affecting ligand binding. In contrast, modification of any of the other 10 Cys residues, either singly or in combinations corresponding to the predicted disulfide bonds, greatly reduced the ability of the corresponding protein to bind IL-2 or either of two mAb (anti-Tac and 7G7/B6) which recognize the Tac protein. Each of the latter mutations also interfered with the molecule's post-translational modification and cell-surface expression. Consistent with these findings, transfection of the L cells with vectors containing truncated Tac cDNA inserts resulted in secretion of Tac fragments capable of ligand binding when the polypeptide chains terminated after Cys-163 (the 10th Cys residue in the full length molecule), but resulted in inactive fragments of Tac which were poorly secreted when they terminated before Cys-163. These findings emphasize the remarkable sensitivity of the active conformation of the Tac molecule to each of the postulated intramolecular disulfide bonds.

Structure-function relationships for the IL-2 receptor system. V. Structure-activity analysis of modified and truncated forms of the Tac receptor protein: site-specific mutagenesis of cysteine residues

IL-2R on activated lymphocytes contain the Tac protein. As part of an effort to characterize this molecule, we examined the structure-activity relationship for each of its 12 Cys residues. A preliminary map of intramolecular disulfide bonding was derived by analysis of cystine-linked enzymatic fragments of the Tac protein. The results indicated that disulfide bonds linked Cys-3 with Cys-147, Cys-131 with Cys-163, and Cys-28,30 with Cys-59,61. The contribution of the Cys residues to an active protein conformation was tested by site-specific mutagenesis, followed by expression of the modified molecules in murine L cells. The results indicated that Cys-192 and -225 could be replaced without affecting ligand binding. In contrast, modification of any of the other 10 Cys residues, either singly or in combinations corresponding to the predicted disulfide bonds, greatly reduced the ability of the corresponding protein to bind IL-2 or either of two mAb (anti-Tac and 7G7/B6) which recognize the Tac protein. Each of the latter mutations also interfered with the molecule's post-translational modification and cell-surface expression. Consistent with these findings, transfection of the L cells with vectors containing truncated Tac cDNA inserts resulted in secretion of Tac fragments capable of ligand binding when the polypeptide chains terminated after Cys-163 (the 10th Cys residue in the full length molecule), but resulted in inactive fragments of Tac which were poorly secreted when they terminated before Cys-163. These findings emphasize the remarkable sensitivity of the active conformation of the Tac molecule to each of the postulated intramolecular disulfide bonds.

Structure function relationships for the IL 2 receptor system. III. Tac protein missing amino acids 102 to 173 (exon 4) is unable to bind IL 2: detection of spliced protein after L cell transfection

High affinity receptors for interleukin 2 (IL 2) contain the Tac protein as one ligand-binding subunit. Localization of the IL 2-binding site on this molecule, as well as localization of the complementary site on IL 2, should provide insight into the design of IL 2 analogs. In this report, we examine the ability of normal and modified Tac protein to bind IL 2 and several antibodies that recognize the native Tac molecule. Using a transient L cell expression system, we have determined that transfection with cDNA-missing Tac exon 4 resulted in expression of spliced protein that had no measurable binding to IL 2 or the monoclonal anti-receptor antibodies, anti-Tac, and 7G7/B6. This protein was detected, however, by rabbit polyclonal antibodies prepared against synthetic Tac peptides. Thus, one or more amino acids encoded by exon 4 is important, either for direct ligand contact or for the proper folding of critical segments of the Tac molecule. In addition, insertion of stop codons at a unique restriction enzyme site near the beginning of exon 5 resulted in cellular secretion of truncated Tac molecules that were capable of binding IL 2, anti-Tac, and 7G7/B6. Amino acids encoded by exons 5 to 8 thus play no critical role in IL 2 binding. The ligand association demonstrated for truncated Tac protein produced by exons 2 to 4 should guide attempts to define the IL 2-binding segment of the Tac molecule.

Structure function relationships for the IL 2 receptor system. III. Tac protein missing amino acids 102 to 173 (exon 4) is unable to bind IL 2: detection of spliced protein after L cell transfection

High affinity receptors for interleukin 2 (IL 2) contain the Tac protein as one ligand-binding subunit. Localization of the IL 2-binding site on this molecule, as well as localization of the complementary site on IL 2, should provide insight into the design of IL 2 analogs. In this report, we examine the ability of normal and modified Tac protein to bind IL 2 and several antibodies that recognize the native Tac molecule. Using a transient L cell expression system, we have determined that transfection with cDNA-missing Tac exon 4 resulted in expression of spliced protein that had no measurable binding to IL 2 or the monoclonal anti-receptor antibodies, anti-Tac, and 7G7/B6. This protein was detected, however, by rabbit polyclonal antibodies prepared against synthetic Tac peptides. Thus, one or more amino acids encoded by exon 4 is important, either for direct ligand contact or for the proper folding of critical segments of the Tac molecule. In addition, insertion of stop codons at a unique restriction enzyme site near the beginning of exon 5 resulted in cellular secretion of truncated Tac molecules that were capable of binding IL 2, anti-Tac, and 7G7/B6. Amino acids encoded by exons 5 to 8 thus play no critical role in IL 2 binding. The ligand association demonstrated for truncated Tac protein produced by exons 2 to 4 should guide attempts to define the IL 2-binding segment of the Tac molecule.

Structure-function relationships for the IL 2-receptor system. I. Localization of a receptor binding site on IL 2

Interleukin 2 (IL 2) modulates the growth and differentiation of a variety of lymphocyte subclasses through its interaction with a specific cell surface receptor. Although both IL 2 and its receptor have been characterized extensively, the location of interaction sites on the two molecules is unknown. Synthetic peptides based on the IL 2 sequence were used to determine the epitopes seen by a number of antibodies reactive with IL 2, some of which inhibited the receptor binding of the factor and the proliferative response of target cells. The results indicated that inhibitory antibodies bound at either of two spatially distinct sites defined by amino acids 8-27 and 33-54. By inference, these segments may also encode distinct contact sites for receptor association. Alternatively, a single contact site may be located between the antibody epitopes in the three-dimensional configuration of the molecule. Although the data did not directly address the role of the C-terminal portion of IL 2, this preliminary localization of receptor contact sites within the N-terminal half of the molecule should prove useful in correlating structure and function during crystallographic analysis of the factor.

Structure-function relationships for the IL 2-receptor system. I. Localization of a receptor binding site on IL 2

Interleukin 2 (IL 2) modulates the growth and differentiation of a variety of lymphocyte subclasses through its interaction with a specific cell surface receptor. Although both IL 2 and its receptor have been characterized extensively, the location of interaction sites on the two molecules is unknown. Synthetic peptides based on the IL 2 sequence were used to determine the epitopes seen by a number of antibodies reactive with IL 2, some of which inhibited the receptor binding of the factor and the proliferative response of target cells. The results indicated that inhibitory antibodies bound at either of two spatially distinct sites defined by amino acids 8-27 and 33-54. By inference, these segments may also encode distinct contact sites for receptor association. Alternatively, a single contact site may be located between the antibody epitopes in the three-dimensional configuration of the molecule. Although the data did not directly address the role of the C-terminal portion of IL 2, this preliminary localization of receptor contact sites within the N-terminal half of the molecule should prove useful in correlating structure and function during crystallographic analysis of the factor.

Structure-function relationships for the IL 2-receptor system. II. Localization of an IL 2 binding site on high and low affinity receptors

The ligand-binding component of high and low affinity IL 2 receptors is a 55,000 m.w. glycoprotein termed Tac. Correlating the structure and function of this molecule should provide insight into the mechanism of IL 2-initiated signal transduction and the structural basis for high and low affinity receptor forms. As a first step in this process, various approaches were used to localize the IL 2 binding region of the Tac molecule. Antibodies prepared to synthetic fragments of Tac were tested for their ability to interfere with IL 2 binding and bioactivity. The results delineated segments in the C-terminal portion of the molecule which appeared to be distal to the ligand binding site. In a more direct approach, radioiodinated IL 2 was cross-linked to high and low affinity receptors, and the resulting complexes were subjected to mild tryptic digestion. Consistent with the antibody data, the IL 2 remained covalently associated with an N-terminal tryptic fragment which apparently consisted of residues 1-83 of the Tac protein. These results suggest that the N-terminal region of the Tac molecule contains important contact sites for ligand-receptor interaction.

Structure-function relationships for the IL 2-receptor system. II. Localization of an IL 2 binding site on high and low affinity receptors

The ligand-binding component of high and low affinity IL 2 receptors is a 55,000 m.w. glycoprotein termed Tac. Correlating the structure and function of this molecule should provide insight into the mechanism of IL 2-initiated signal transduction and the structural basis for high and low affinity receptor forms. As a first step in this process, various approaches were used to localize the IL 2 binding region of the Tac molecule. Antibodies prepared to synthetic fragments of Tac were tested for their ability to interfere with IL 2 binding and bioactivity. The results delineated segments in the C-terminal portion of the molecule which appeared to be distal to the ligand binding site. In a more direct approach, radioiodinated IL 2 was cross-linked to high and low affinity receptors, and the resulting complexes were subjected to mild tryptic digestion. Consistent with the antibody data, the IL 2 remained covalently associated with an N-terminal tryptic fragment which apparently consisted of residues 1-83 of the Tac protein. These results suggest that the N-terminal region of the Tac molecule contains important contact sites for ligand-receptor interaction.

Monoclonal antibody to human cytochrome c: effect on electron-transfer reactions

A monoclonal antibody has been produced to an antigenic site on human cytochrome c which includes amino acid number 58 (isoleucine). This area is on the bottom back of the cytochrome, removed from the postulated binding/reaction sites for oxidase and reductase, but in the area of the molecule where an appreciable change in conformation is seen on oxidation-reduction. In spectrophotometric assays, where binding of cytochrome c to the oxidase or reductase is rate-limiting, the antibody gave stimulation of the reductase reaction under some conditions, where the oxidase reaction was inhibited. Also variation of the pH of the reaction medium resulted in differential effects on the oxidase and reductase reactions. Different effects of the antibody were seen when the oxidase was assayed polarographically, as compared to the spectrophotometric measurements. The data show that the binding/reaction sites on cytochrome c for the oxidase and reductase must be different. They suggest that binding of antibody may affect conformational changes in the whole molecule, distorting the binding/reaction sites. Conformational changes may be involved as a control mechanism in cytochrome c-mediated electron-transfer reactions.

Monoclonal antibodies to cytochrome c from Paracoccus denitrificans: effects on electron transport reactions

The effect of a monoclonal antibody to a soluble cytochrome c from Paracoccus denitrificans was tested on the membrane-bound electron-transport system of this bacterium. This antibody (F3-10.2) and one previously described (F3-29.4) (Kuo, L.M., Davies, H.C. and Smith, L. (1984) Biochim. Biophys. Acta 766, 472-482) were deduced to bind to the cytochrome c in the area including amino acid residue number 23 on a loop on the side of the heme crevice. In contrast to the observations with the previously tested antibody, the present data show the second antibody to block completely the reaction of the cytochrome c with cytochrome c oxidase but not that with cytochrome c reductase. Neither antibody has an appreciable inhibitory effect on the NADH oxidase of the isolated detergent-treated membranes. The two antibodies bind in different ways, giving insight into the interaction of a soluble protein with membrane-bound enzymes. The data indicate that the reaction sites on the cytochrome c for the oxidase and reductase moieties of P. denitrificans are different. They also argue against the need for a dissociable cytochrome c comparable to that which functions on the mitochondrial inner membrane.

Effects of monoclonal antibodies to bovine and Paracoccus denitrificans cytochromes c on reactions with oxidase, reductase and peroxidase

The effects of monoclonal antibodies to bovine and Paracoccus denitrificans cytochromes c (Kuo, L.M. and Davies, H.C. (1983) Mol. Immunol. 20, 827-838) in the reactions of the cytochromes c with cytochrome c oxidase, reductase and peroxidase were studied. Spectrophotometric assays were employed, under conditions where binding of cytochrome c to the enzymes appears to be rate-limiting. Less than stoichiometric amounts of antibodies to P. denitrificans cytochrome c added to the cytochrome rendered some of it nonoxidizable or nonreducible by the P. denitrificans membrane-bound electron transport system and decreased the rate constant with the remaining cytochrome c. The antibodies appear to affect both electron transport reactions (blocking effects) with the oxidase and reductase and binding effects (effects on rate constants) and to distinguish between the two. Different ratios of antibody site to cytochrome c gave different extents of blocking of the reductase as compared with the oxidase reaction. Differences were also apparent in the effect of these antibodies on the reaction of yeast peroxidase and the oxidase with the P. denitrificans cytochrome c. Antibodies to bovine and P. denitrificans cytochromes c had considerably less effect on the reactions of the bovine cytochrome with bovine oxidase and reductase. One antibody was inhibitory to the oxidase reaction with bovine cytochrome c, but not to that with the reductase. Also, an antibody which inhibited the oxidase reaction had no effect on the reaction with yeast peroxidase. The data give evidence that the interaction areas on cytochrome c for oxidase and reductase and peroxidase are not identical, although they may be nearby.

Production, isolation and characterization of monoclonal antibodies to cytochromes c of beef heart and Paracoccus denitrificans

Hybridoma cell lines secreting monoclonal antibodies which bind beef heart cytochrome c or Paracoccus denitrificans cytochrome c have been produced using spleen cells from BALB/c mice immunized with cytochrome c. Immunization was performed with either the native cytochrome c, succinylated hemocyanin-conjugated cytochrome c, or beef heart cytochrome c polymerized with glutaraldehyde. Of 10 such fusions, the hybridization frequency ranged from 0 to 42%. The cell fusion efficiency, the possible factors involved in the cell fusion efficiency and the frequency of antibody producing hybridomas are described. The percentage of hybridomas positive for anti-cytochrome c antibody production as screened for by radioimmunoassay or ELISA was 2%. Of the antibodies from 12 hybridoma cell lines which resulted from 10 fusions, three were specific to beef heart cytochrome c, another three were specific to P. denitrificans cytochrome c, and the remainder reacted with both cytochromes c. These groups of monoclonal antibodies react to different sets of sites on these two cytochromes c. The monoclonal antibodies from ten representative clones have been isolated and characterized by different methods.

Suppression of the formation of polygenotypic recombinant colonies by a maf mutation in mating with HfrH

W3011, a Cavalli-type Hfr (HfrC), was mated with F-KY9474, maf-1, which cannot maintain F or F-like plasmids, and with F-OU9474, Maf+, a spontaneous revertant of KY9474. The recombinant colonies obtained were 100% monogenotypic from KY9474 and 90% monogenotypic from OU9474. On the other hand, in matings with OU11, a Hayes-type Hfr (HfrH), and these two F- strains, recombinant colonies derived from KY9474 showed only 22% polygenotypic recombinant colonies; whereas, those derived from OU9474 showed a high production rate (57%) of polygenotypic recombinant colonies. Among the polygenotypic recombinant colonies derived from KY9474 maf-1, 50% contained three or more recombinant types. These were probably derived from a small fraction of Maf+ revertants in the KY9474 population, as suggested by the results of mating this strain with M80, an F' strain that contains an amber mutation in traH. These results support the hypothesis that the donor DNA fragments derived from an HfrH can undergo a limited replication in the recipient to produce polygenotypic recombinant colonies, whereas those derived from HfrC cannot.