Intrathymic deletion of MHC class I-restricted cytotoxic T cell precursors by constitutive cross-presentation of exogenous antigen

Cross-priming of cytotoxic T lymphocytes by professional antigen-presenting cells (APC) is a potential hazard to self tolerance because it exposes naive T cells to tissue-specific self antigens in the context of co-stimulatory signals. Here we show that cross-presentation of exogenous material occurs constitutively within the thymus. Although efficient cross-presentation is a property of relatively few APC it results in thymocyte deletion both in vitro and in vivo, suggesting that intrathymic cross-presentation can operate as an effective component of tolerance to circulating self antigens. The capacity of minor cell populations to mediate thymocyte deletion but not positive selection reflects an underlying difference in the biology of these two processes.

Alternate forms reliability of the assessment of motor and process skills

The purpose of this study is to examine the alternate forms reliability of the AMPS (Assessment of Motor and Process Skills) (Fisher, 1997a) where alternate forms means different pairs of AMPS tasks. The participants for this study were persons selected from the AMPS database who had performed four AMPS tasks. The participants varied in age, gender, diagnosis, and level of assistance needed to live in the community. The AMPS was administered by trained and calibrated occupational therapists according to standardized procedures. The data for the 91 participants were subjected to 12 many-faceted Rasch analyses to generate ADL motor and ADL process ability measures for each task and each set of paired tasks. Repeated measures ANOVAs revealed no time effect across the four AMPS tasks. Pearson product moment correlations between Tasks 1 and 2 combined and Tasks 3 and 4 combined were r = .91 and r = .86 for the ADL motor and ADL process scales, respectively. Calculation of the standardized difference (z) revealed that no more than 8% of the participants had ADL motor or ADL process ability measures that differed significantly between observations once we accounted for real differences in a persons performance; 80% of the paired ADL motor and ADL process ability measures remained stable within +/- 0.5 logits when the participants performed two tasks. The AMPS ADL motor and ADL process scales can be used reliably in clinical practice and for research purposes.

Dynamic repositioning of genes in the nucleus of lymphocytes preparing for cell division

We show that several transcriptionally inactive genes localize to centromeric heterochromatin in the nucleus of cycling but not quiescent (noncycling) primary B lymphocytes. In quiescent cells, centromeric repositioning of inactive loci was induced after mitogenic stimulation. A dynamic repositioning of selected genes was also observed in developing T cells. Rag and TdT loci were shown to relocate to centromeric domains following heritable gene silencing in primary CD4+8+ thymocytes, but not in a phenotypically similar cell line in which silencing occurred but was not heritable. Collectively, these data indicate that the spatial organization of genes in cycling and noncycling lymphocytes is different and that locus repositioning may be a feature of heritable gene silencing.

The dimensionality and validity of the Older Americans Resources and Services (OARS) Activities of Daily Living (ADL) Scale

The psychometric properties of the OARS ADL scale, comprised of seven physical activities of daily living (PADL) and seven instrumental activities of daily living (IADL) items, were examined using a Rasch measurement approach. Two of the PADL items failed to demonstrate acceptable goodness-of-fit with the measurement model but the remaining 12 items could be combined into a single measure of ADL ability. Although the OARS ADL scale was designed to identify those community-dwelling elderly who need supports and services to continue to live in the community, the scale items were found to be poorly targeted to community-dwelling elderly since almost half of our sample received maximal scores. Rasch analysis identified how we might improve the sensitivity of the OARS ADL scale but its utility in outcome and longitudinal studies remains questionable.

Uniting practice and theory in an occupational framework. 1998 Eleanor Clarke Slagle Lecture

The term occupation conveys the powerful essence of our profession--enabling people to seize, take possession of, or occupy the spaces, time, and roles of their lives. Occupation is activity that is both purposeful and meaningful to the person who engages in it. Our uniqueness lies in our use of occupation as a therapeutic agent, but our unique focus on occupation is not always apparent in practice. Four global groups of activities that occupational therapy practitioners use in practice are described--exercise, contrived occupation, therapeutic occupation, and adaptive occupation. Therapeutic occupation and adaptive occupation are proposed as the legitimate activities of occupational therapy. The Occupational Therapy Intervention Process Model is then presented. This model stresses a top-down approach to evaluation and provides a framework for implementing adaptive occupation for purposes of compensation as well as therapeutic occupation for purposes of remediation.

Environment effect of functional task performance in adults with acquired brain injuries: use of the assessment of motor and process skills

OBJECTIVE

To examine household task performance in both familiar (home) and unfamiliar (clinic) environments in adults with acquired brain injuries.

DESIGN

The research performed was a comparison study examining the effect of the environment on functional task performance. Individuals were evaluated using the Assessment of Motor and Process Skills both in their homes and in an unfamiliar clinic setting.

PARTICIPANTS

Twenty individuals with acquired brain injuries living in the community.

MAIN OUTCOME MEASURES

The Assessment of Motor and Process Skills, an observational, standardized, occupational therapy assessment tool, was used to evaluate household task performance.

RESULTS

Paired one-tailed t tests indicated a significant difference between home and clinic performance measures in process ability (t=-4.28, p=.00), but no significant difference in motor ability performance measures (t=-1.84, p=.410). Scatter plot analyses showed that performance scores of 6 of the 20 subjects differed in a clinically meaningful way, and that instrumental activities of daily living motor performance scores for 3 of the 20 differed in a clinically meaningful way.

CONCLUSIONS

Individuals with acquired brain injuries may be influenced by their environment when performing household tasks, although further study is necessary to determine the extent of the environmental effect.

Helios, a T cell-restricted Ikaros family member that quantitatively associates with Ikaros at centromeric heterochromatin

The Ikaros gene encodes multiple protein isoforms that contribute critical functions during the development of lymphocytes and other hematopoietic cell types. The intracellular functions of Ikaros are not known, although recent studies have shown that Ikaros proteins colocalize with inactive genes and centromeric heterochromatin. In this study, Ikaros proteins were found to be components of highly stable complexes. The complexes from an immature T cell line were purified, revealing associated proteins of 70 and 30 kD. The p70 gene, named Helios, encodes two protein isoforms with zinc finger domains exhibiting considerable homology to those within Ikaros proteins. Helios and Ikaros recognize similar DNA sequences and, when overexpressed, Helios associates indiscriminately with the various Ikaros isoforms. Although Ikaros is present in most hematopoietic cells, Helios was found primarily in T cells. The relevance of the Ikaros-Helios interaction in T cells is supported by the quantitative association of Helios with a fraction of the Ikaros. Interestingly, the Ikaros-Helios complexes localize to the centromeric regions of T cell nuclei, similar to the Ikaros localization previously observed in B cells. Unlike the B cell results, however, only a fraction of the Ikaros, presumably the fraction associated with Helios, exhibited centromeric localization in T cells. These results establish immunoaffinity chromatography as a useful method for identifying Ikaros partners and suggest that Helios is a limiting regulatory subunit for Ikaros within centromeric heterochromatin.

Association of transcriptionally silent genes with Ikaros complexes at centromeric heterochromatin

Ikaros proteins are required for normal T, B, and NK cell development and are postulated to activate lymphocyte-specific gene expression. Here we examined Ikaros distribution in the nucleus of B lymphocytes using confocal microscopy and a novel immunofluorescence in situ hybridization (immuno-FISH) approach. Unexpectedly, Ikaros localized to discrete heterochromatin-containing foci in interphase nuclei, which comprise clusters of centromeric DNA as defined by gamma-satellite sequences and the abundance of heterochromatin protein-1 (HP-1). Using locus-specific probes for CD2, CD4, CD8alpha, CD19, CD45, and lambda5 genes, we show that transcriptionally inactive but not transcriptionally active genes associate with Ikaros-heterochromatin foci. These findings support a model of organization of the nucleus in which repressed genes are selectively recruited into centromeric domains.

How many thymocytes audition for selection?

T cell maturation requires the rearrangement of clonotypic T cell receptors (TCR) capable of interacting with major histocompatibility complex (MHC) ligands to initiate positive and negative selection. Only 3-5% of thymocytes mature to join the peripheral T cell pool. To investigate the basis for this low success rate, we have measured the frequency of preselection thymocytes capable of responding to MHC. As many as one in five MHC-naive thymocytes show upregulation of activation markers on exposure to MHC-expressing thymic stroma in short-term reaggregate culture. The majority of these cells display physiological changes consistent with entry into the selection process within 24 h. By exposing TCR transgenic thymocytes to a range of MHC-peptide complexes, we show that CD69 induction is indicative of thymocyte selection, positive or negative. Our data provide evidence that the fraction of thymocytes that qualify to enter the thymic selection process far exceeds the fraction that successfully complete it, and suggest that most MHC-reactive thymocytes are actively eliminated in the course of selection.

Rational primer design greatly improves differential display-PCR (DD-PCR)

Since its conception in 1992, differential display PCR (DD-PCR) has attracted widespread interest. Theoretically an attractive cloning approach, it combines the comparative analysis of several samples with the sensitivity of PCR. Although a large number of studies embracing this technology have been initiated, few novel genes of interest have been identified, suggesting that the method has not realised its potential. The present report shows that by modifying primer design, sampling of differentially expressed genes can be greatly enhanced and relevant genes can be isolated. Using our modified conditions DD-PCR efficiently screens a wide range of gene expression levels, in which differences are represented on a linear scale.

Effects of familiarity of task and choice on the functional performance of younger and older adults

An experiment was conducted to compare the functional performance of younger and older adults on familiar and unfamiliar tasks under 2 conditions of perceived control. Specifically, the relation between age and motor and process skills was examined. The familiar tasks were simple cooking tasks, whereas the unfamiliar tasks were contrived, meaningless tasks developed for this study. Younger and older adults did not differ in the ratings of the familiarity of the tasks, but results from 2 Age x Task x Choice analyses of variance demonstrated a significant age difference for motor and process skills under all conditions. This suggests that older adults demonstrate age-related decline, even with activities that take motivational, experiential, and ecological validity components into account. For the process skills scale, there was also a significant main effect for choice. These results support the concept that perceived control may improve performance, but not differentially for older adults; that is, younger and older adults both demonstrated improved process performance when given their choice of tasks.

Effects of familiarity of task and choice on the functional performance of younger and older adults

An experiment was conducted to compare the functional performance of younger and older adults on familiar and unfamiliar tasks under 2 conditions of perceived control. Specifically, the relation between age and motor and process skills was examined. The familiar tasks were simple cooking tasks, whereas the unfamiliar tasks were contrived, meaningless tasks developed for this study. Younger and older adults did not differ in the ratings of the familiarity of the tasks, but results from 2 Age x Task x Choice analyses of variance demonstrated a significant age difference for motor and process skills under all conditions. This suggests that older adults demonstrate age-related decline, even with activities that take motivational, experiential, and ecological validity components into account. For the process skills scale, there was also a significant main effect for choice. These results support the concept that perceived control may improve performance, but not differentially for older adults; that is, younger and older adults both demonstrated improved process performance when given their choice of tasks.

Measuring functional competence in older persons with Alzheimer's disease

Despite their limitations, mental status tests and self/proxy reports of instrumental activities of daily living (IADL) are often used to predict functional competence. In contrast, the Assessment of Motor and Process Skills (AMPS) is a direct observational assessment of IADL competence. Sixty-four community-dwelling elderly (20 Alzheimer's disease [AD] patients and 44 nondemented) were assessed with the AMPS, the Mini-Mental State Examination (MMSE), and the Older Americans Resources and Services (OARS)-IADL. Performance on all three assessments was significantly lower for the AD sample. The MMSE did not correlate significantly with the AMPS motor ability measures but it correlated modestly with the AMPS process ability measures. The OARS-IADL correlated significantly with the AMPS motor ability measure for the nondemented sample alone. Although mental status and self/proxy assessments provide some insight into individuals' IADL competence, direct observation of IADL task performance provides additional information regarding the subtle process and motor skills changes that occur in progressive dementing conditions.

The assessment of motor and process skills applied cross-culturally to the Japanese

OBJECTIVES

The purposes of this study were to examine the cross-cultural validity of the Assessment of Motor and Process Skills (AMPS) as well as the reliability of raters from different cultures.

METHOD

Six trained raters from diverse cultural backgrounds scored 10 Japanese subjects' performances on familiar and culturally relevant tasks of their own choosing.

RESULTS

Results indicated high cross-cultural validity and interrater reliability for the AMPS, as indicated by goodness of fit of subjects and raters via the many-faceted Rasch measurement model. The relative rater severity was also evaluated cross-culturally by the standardized difference (z). The Japanese rater and one of the three American raters varied significantly in severity between their scoring of Japanese subjects versus European subjects.

CONCLUSION

The results support the hypothesis that the AMPS can be used as a cross cultural instrumental activities of daily living assessment. Further study is needed to clarify the issue of possible cultural bias in rater severity.

Male and female performance on the assessment of motor and process skills

OBJECTIVE

To examine the validity of the assertion that men and women do not differ significantly on the Assessment of Motor and Process Skills (AMPS), a functional assessment tool used to evaluate the interaction between component motor and process skills and IADL (instrumental or domestic activities of daily living) performance capacity.

DESIGN

Descriptive comparison. Using many-faceted Rasch analysis, the AMPS motor and process scales were examined for differential item response between gender subgroups. Mean motor and process ability measures of age-matched groups of male and female subjects were also compared.

PARTICIPANTS

A convenience sample of more than 3,500 men and women from the standardization sample for the pilot version of the AMPS computer-scoring software. The subjects had a variety of physical disabilities or psychiatric diagnoses.

MAIN OUTCOME MEASURES

Hypotheses were as follows: (1) no differential item response would be found on the motor or process scales; (2) if differential item response was found, it would not have an impact on the final estimation of client ability; (3) men and women would not differ in mean AMPS motor or process ability.

RESULTS

Of the 36 AMPS items, only one (Lifts) differed between men and women. This differential item response did not disrupt the final estimation of client ability. Men and women did not differ in mean motor ability. Women on the whole were more able than men in mean process ability.

CONCLUSIONS

The AMPS is valid for use across gender subgroups. Men and women do not differ in AMPS motor ability, but overall, women are slightly more able than men in AMPS process ability.

Differences between persons with right or left cerebral vascular accident on the Assessment of Motor and Process Skills

OBJECTIVE

Persons with right and left cerebral vascular accident (RCVA and LCVA) differ in terms of discrete impairments, but there is limited information with regard to how such impairments translate into differences in disability. The following hypotheses were tested: (1) persons with stroke have lower instrumental or domestic activities of daily living (IADL) ability than do matched nondisabled controls, (2) persons with RCVA do not differ from persons with LCVA in IADL ability, and (3) persons with RCVA and LCVA differ in specific motor and process skills that affect IADL performance.

DESIGN

Descriptive comparison.

SETTING

Subjects were tested in settings where rehabilitation services were received (home or clinic).

SUBJECTS

71 persons with RCVA, 76 persons with LCVA, and 83 community-living nondisabled individuals drawn from the Assessment of Motor and Process Skills (AMPS) database, matched for age, gender, and number of tasks performed.

MAIN OUTCOME MEASURE

AMPS, designed to measure type and severity of impairments manifested in the context of IADL performance. The AMPS was administered to all subjects in accordance with standardized testing procedures.

RESULTS

The two stroke groups did not differ significantly in IADL ability, but both stroke groups had significantly lower IADL performance than did the nondisabled subjects. On the AMPS motor scale, persons with RCVA demonstrated greater impairment in pacing, transporting, and coordinating two body parts. Persons with LCVA demonstrated greater impairments in calibrating movements. No differences were found between the two groups in AMPS process skills.

CONCLUSIONS

Persons with RCVA and LCVA have hemisphere-specific differences in motor impairments, but do not differ significantly in IADL ability.

Lymphoproliferative disorders in IL-7 transgenic mice: expansion of immature B cells which retain macrophage potential

Transgenic mice carrying the murine IL-7 gene under the MHC class II (E alpha) promoter are described which develop lymphoid tumours at a high incidence when maintained in conventional or specific pathogen-free environments. Cells obtained from the lesions were relatively monomorphic, expressed a variety of B cell associated markers (BP-1, B220, CD43) but lacked surface Ig. Some mice, showed expanded populations of cells phenotypically similar to the recently reported bipotent B/macrophage stem cell subset (AA4.1high, B220-, Ig-) which could be cloned and maintained in vitro. These cells expressed IL-7 receptors, proliferated in response to IL-7 and in most cases had germline configuration of the Ig heavy chain locus. Cell lines cloned from two such tumours generated macrophages spontaneously in culture, consistent with their bipotent B cell/macrophage phenotype. These results suggest that IL-7 plays a role in very early stages of B cell ontogeny prior to bona fide B cell commitment.

Expression of functional MHC class II molecules by a mouse pro-B cell clone

We describe here the G12 pro-B cell clone that has been isolated from an IL-7 transgenic mouse. This clone has the phenotype B220+, BP-1+, HSA+, CD43+, lambda5+, and CD25-, and has its Ig locus in a germline configuration. G12 cells spontaneously express cell-surface MHC class II molecules, although to a much lesser extent than the mature M12.4.1 B-cell lymphoma. G12 cells can process and present the native Hen Egg Lysozyme (HEL) to an MHC class II-restricted T-cell hybridoma. The efficiency of presentation is inferior to that obtained with M12.4.1 cells. This is the first report where a pro-B cell can serve as APC in an MHC class II-restricted presentation.

Does the Q angle reflect the force on the patella in the frontal plane?

BACKGROUND AND PURPOSE

The quadriceps femoris muscle angle (Q angle) is used to reflect the quadriceps femoris muscle's force on the patella in the frontal plane. We found no studies, however, that validate this assumption. The purpose of this study was to determine whether the Q angle can be used to represent the force on the patella in the frontal plane.

SUBJECTS

Seven lower extremities from four male cadavers were dissected and investigated.

METHODS

We devised a model in which the line of action of quadriceps femoris muscle's resultant force was calculated in the frontal plane on the seven lower-extremity specimens. We then compared these calculations with the Q angles from the same cadaver specimens. The differences between the measured and calculated Q angles were tested for significance using a paired t test. In addition, we calculated a simple linear regression to test the relationship between the calculated and measured Q angles.

RESULTS

Our data showed that the angle for the average resultant force of the quadriceps femoris muscle was 3.90 degrees greater (P = .0003) than the measured Q angles. A significant relationship (r = .919, P = .0035); however, was found between the measured and calculated Q angles.

CONCLUSION AND DISCUSSION

The Q angle, as measured in clinical practice, appears to reflect the angle of the resultant quadriceps femoris muscle force. We believe, however, that this measurement is significantly less than the actual quadriceps femoris muscle force vector and underestimates the lateral force on the patella.

The Assessment of Motor and Process Skills of persons with psychiatric disorders

OBJECTIVES

The purpose of this study was to examine the discriminant validity of the Assessment of Motor and Process Skills (AMPS) when used to evaluate a heterogeneous sample of subjects with psychiatric disorders.

METHOD

Sixty subjects, ranging in age from 16 to 72 years, participated in this study; 30 were persons without disorders living in the community; 30 had diagnosed psychiatric disorders. Two univariate F tests were used to test the hypothesis that mean AMPS measures would differ significantly between the group with and the group without psychiatric disorders.

RESULTS

The hypothesis was supported for both AMPS motor and process scale measures. As would be expected among a sample that includes many higher functioning persons, many subjects with psychiatric disorders did just as well as subjects in the group without psychiatric disorders.

CONCLUSIONS

Motor as well as process skill abilities of persons with psychiatric disorders should be evaluated. Because the AMPS provides more specific features than other global functional instruments, it can help clinicians plan treatment and intervention more effectively. Further examination of the motor and process skill deficits within and among diagnostic subgroups and of the effect of medication and prolonged hospitalization on AMPS motor and process abilities is indicated.

Comparing motor and process ability of persons with suspected dementia in home and clinic settings

OBJECTIVES

Evaluating functional level of persons with diagnosed or suspected dementia is an important part of occupational therapy. The importance of the environment is often highlighted. We investigated the ability of clients with suspected dementia to perform instrumental activities of daily living (IADLs) in the clinic versus in their homes.

METHOD

We used the Assessment of Motor and Process Skills (AMPS) to measure the motor and process skill ability of 19 clients with suspected dementia.

RESULTS

Using two-tailed paired t-tests, we found no overall difference in IADL motor or process performance between the clinic and home setting. However, of the 19 clients, 6 had motor ability measures, whereas 5 had process ability measures that differed significantly between the two settings.

CONCLUSION

The results suggest that if we want to know how a person with suspected dementia performs in IADLs in a specific environment we should test him or her in that environment.

Using the assessment of motor and process skills to compare occupational performance between clinic and home settings

OBJECTIVES

The study described in this article examined the effect of home versus clinic settings on the instrumental activities of daily living (IADL) performance of older adults.

METHOD

Twenty older adults living in the community were evaluated in their homes and in an occupational therapy clinic with the Assessment of Motor and Process Skills (AMPS). The motor and process ability measures were compared between the two settings with many-faceted Rasch analysis.

RESULTS

The subjects' motor ability measures tended to remain stable from clinic to home settings. The process ability measures tended not to remain stable from clinic to home settings, because 10 of the 20 subjects performed significantly better in their homes.

CONCLUSION

These findings support the idea that process skill abilities are affected by the environment to a greater degree than are motor skills abilities and that for persons living in the community, the familiar home environment tends to support IADL performance. If an occupational therapist wants to know how a person performs IADLs, the therapist should evaluate that person's performance in the environment in which the client will be functioning.

Functional competence of community-dwelling persons with multiple sclerosis using the assessment of motor and process skills

The Assessment of Motor and Process Skills (AMPS) is an observational measure of functional competence in instrumental activities of daily living (IADL) that was designed to overcome the limitations of self reports and proxy reports. The AMPS allows simultaneous evaluation of the underlying motor and process (organizational/adaptive) skills necessary for competent task performance. We examined the IADL performance of 22 community-dwelling patients with mild to moderate MS in comparison to nondisabled subjects matched for age and gender. Functional competence of the MS subjects, as measured by the AMPS, was poorer than that of the control group. Many MS subjects who would not have been expected to have IADL difficulties on the basis of ratings of neurologic impairment were impaired in their IADL performance. For some patients, IADL impairment reflected deficits in their motor and process skills, whereas for others, process skill impairments alone were responsible for deficient task performance.

The effects of different percentages of dietary fat intake, exercise, and calorie restriction on body composition and body weight in obese females

PURPOSE

The goal of this study was to determine the effect of varying the amount of dietary fat, while holding calories at 1,200 kcals/day, on body weight and percent body fat in 35 obese women.

DESIGN

A pretest, midtest, posttest experimental design was employed, and subjects were randomly divided into one of four dietary fat groups, with 10%, 20%, 30%, or 40% of caloric intake as dietary fat.

INTERVENTION

Subjects consumed 1,200 kcals/day and a specified percentage of total energy as fat, depending on their dietary group. Protein was held constant at 20%. All subjects engaged in a five day/week walking program.

SETTING

Participants were recruited from the general community using newspaper advertisements.

SUBJECTS

Thirty-five obese women 25 to 45 years of age (means=38 +/- 4.97) served as subjects. All were at least 20% above ideal weight and 30% to 52% body fat.

MEASURES

Percent body fat, body weight, and anthropomorphic measurements were taken at baseline, six and 12 weeks. Dietary intake was recorded daily by each subject, and exercise walking logs were maintained by each participant.

RESULTS

All subjects lost body weight and body fat; however, there were no significant differences in the rate or amount of body weight or percent body fat lost across the four groups during the intervention.

CONCLUSIONS

It appears that during calorie restriction and exercise for 12 weeks, percent of calories derived from dietary fats does not influence loss of body weight or percent body fat in adult obese women.