H - 71 Development and Implementation of a Neuropsychology Program for Spanish-Speaking Patients at Cleveland Clinic Nevada

OBJECTIVE

There is a significant need for culturally-informed neuropsychology services for patients from underrepresented communities, particularly those with limited English proficiency. Given the finite number of bilingual neuropsychologists, working with interpreters and bilingual psychometrists is important for increasing access to equitable care, though many neuropsychologists lack training in these approaches. We present a model for the development and implementation of a neuropsychology program for Spanish-speaking patients in an outpatient academic medical setting.

METHOD

To develop our service, we first identified the primary patient population to be served and common referral questions. We then consulted with national and international experts to identify best practices for establishing a new clinical service line for Spanish-speaking patients, which included a survey of available Spanish-language tests and normative data, resources for interpretation, and case consultation.

RESULTS

After consulting with colleagues at Cleveland Clinic Ohio and UCLA, we established a formal consultation agreement with a multilingual neuropsychologist with expertise in program development. Consultation focused on best practices for working with interpreters and Hispanic patients, selection of tests and normative sources, and ongoing clinical case consultation. The new service was initiated in March 2023 and includes conducting clinical interviews with virtual interpreters and testing by a bilingual psychometrist. Comprehensive assessments are currently being provided for Spanish-speaking patients, and trainees also receive experience and supervision with these cases.

CONCLUSIONS

Developing clinical neuropsychology services for culturally- and linguistically-diverse patients is critically needed. In addition to addressing barriers to care, ensuring high-quality evaluations through prospective consultation with dedicated experts is important for program development.

Global rural health disparities in Alzheimer's disease and related dementias: State of the science

INTRODUCTION

Individuals living in rural communities are at heightened risk for Alzheimer's disease and related dementias (ADRD), which parallels other persistent place-based health disparities. Identifying multiple potentially modifiable risk factors specific to rural areas that contribute to ADRD is an essential first step in understanding the complex interplay between various barriers and facilitators.

METHODS

An interdisciplinary, international group of ADRD researchers convened to address the overarching question of: "What can be done to begin minimizing the rural health disparities that contribute uniquely to ADRD?" In this state of the science appraisal, we explore what is known about the biological, behavioral, sociocultural, and environmental influences on ADRD disparities in rural settings.

RESULTS

A range of individual, interpersonal, and community factors were identified, including strengths of rural residents in facilitating healthy aging lifestyle interventions.

DISCUSSION

A location dynamics model and ADRD-focused future directions are offered for guiding rural practitioners, researchers, and policymakers in mitigating rural disparities.

HIGHLIGHTS

Rural residents face heightened Alzheimer's disease and related dementia (ADRD) risks and burdens due to health disparities. Defining the unique rural barriers and facilitators to cognitive health yields insight. The strengths and resilience of rural residents can mitigate ADRD-related challenges. A novel "location dynamics" model guides assessment of rural-specific ADRD issues.

Evaluation of Neighborhood-Level Disadvantage and Cognition in Mexican American and Non-Hispanic White Adults 50 Years and Older in the US

Importance

Understanding how socioeconomic factors are associated with cognitive aging is important for addressing health disparities in Alzheimer disease.

Objective

To examine the association of neighborhood disadvantage with cognition among a multiethnic cohort of older adults.

Design, Setting, and Participants

In this cross-sectional study, data were collected between September 1, 2017, and May 31, 2022. Participants were from the Health and Aging Brain Study-Health Disparities, which is a community-based single-center study in the Dallas/Fort Worth area of Texas. A total of 1614 Mexican American and non-Hispanic White adults 50 years and older were included.

Exposure

Neighborhood disadvantage for participants' current residence was measured by the validated Area Deprivation Index (ADI); ADI Texas state deciles were converted to quintiles, with quintile 1 representing the least disadvantaged area and quintile 5 the most disadvantaged area. Covariates included age, sex, and educational level.

Main Outcomes and Measures

Performance on cognitive tests assessing memory, language, attention, processing speed, and executive functioning; measures included the Spanish-English Verbal Learning Test (SEVLT) Learning and Delayed Recall subscales; Wechsler Memory Scale, third edition (WMS-III) Digit Span Forward, Digit Span Backward, and Logical Memory 1 and 2 subscales; Trail Making Test (TMT) parts A and B; Digit Symbol Substitution Test (DSST); Letter Fluency; and Animal Naming. Raw scores were used for analyses. Associations between neighborhood disadvantage and neuropsychological performance were examined via demographically adjusted linear regression models stratified by ethnic group.

Results

Among 1614 older adults (mean [SD] age, 66.3 [8.7] years; 980 women [60.7%]), 853 were Mexican American (mean [SD] age, 63.9 [7.9] years; 566 women [66.4%]), and 761 were non-Hispanic White (mean [SD] age, 69.1 [8.7] years; 414 women [54.4%]). Older Mexican American adults were more likely to reside in the most disadvantaged areas (ADI quintiles 3-5), with 280 individuals (32.8%) living in ADI quintile 5, whereas a large proportion of older non-Hispanic White adults resided in ADI quintile 1 (296 individuals [38.9%]). Mexican American individuals living in more disadvantaged areas had worse performance than those living in ADI quintile 1 on 7 of 11 cognitive tests, including SEVLT Learning (ADI quintile 5: β = -2.50; 95% CI, -4.46 to -0.54), SEVLT Delayed Recall (eg, ADI quintile 3: β = -1.11; 95% CI, -1.97 to -0.24), WMS-III Digit Span Forward (eg, ADI quintile 4: β = -1.14; 95% CI, -1.60 to -0.67), TMT part A (ADI quintile 5: β = 7.85; 95% CI, 1.28-14.42), TMT part B (eg, ADI quintile 5: β = 31.5; 95% CI, 12.16-51.35), Letter Fluency (ADI quintile 4: β = -2.91; 95% CI, -5.39 to -0.43), and DSST (eg, ADI quintile 5: β = -4.45; 95% CI, -6.77 to -2.14). In contrast, only non-Hispanic White individuals living in ADI quintile 4 had worse performance than those living in ADI quintile 1 on 4 of 11 cognitive tests, including SEVLT Learning (β = -2.35; 95% CI, -4.40 to -0.30), SEVLT Delayed Recall (β = -0.95; 95% CI, -1.73 to -0.17), TMT part B (β = 15.95; 95% CI, 2.47-29.44), and DSST (β = -3.96; 95% CI, -6.49 to -1.43).

Conclusions and Relevance

In this cross-sectional study, aging in a disadvantaged area was associated with worse cognitive functioning, particularly for older Mexican American adults. Future studies examining the implications of exposure to neighborhood disadvantage across the life span will be important for improving cognitive outcomes in diverse populations.

Future directions in neuropsychology: training, education, clinical practice, and advocacy for Asians and Asian Americans

Objective: Given the need for increased equity, justice, and inclusion in neuropsychology, this paper aimed to present an initial perspective on key areas of understanding necessary to provide ethically and culturally responsive services and training to Asians and Asian Americans. Method: We first reviewed the terms Asian and Asian American and established the large multitude of individuals these terms encompass. Second, a brief review of the foundations for Asian American psychology is provided to set the stage for the unique considerations when evaluating individuals of Asian descent. Lastly, the necessity of using the social justice lens in education and training pipelines needed to propel the field forward is emphasized. Conclusions: Overall, this paper reviewed key information to provide a foundational level of understanding regarding the nuances of working with persons of Asian descent in the field of neuropsychology.

Microglial Imaging in Alzheimer's Disease and Its Relationship to Brain Amyloid: A Human 18F-GE180 PET Study

BACKGROUND

Emerging evidence suggests a potential causal role of neuroinflammation in Alzheimer's disease (AD). Using positron emission tomography (PET) to image overexpressed 18 kDA translocator protein (TSPO) by activated microglia has gained increasing interest. The uptake of 18F-GE180 TSPO PET was observed to co-localize with inflammatory markers and have a two-stage association with amyloid PET in mice. Very few studies evaluated the diagnostic power of 18F-GE180 PET in AD population and its interpretation in human remains controversial about whether it is a marker of microglial activation or merely reflects disrupted blood-brain barrier integrity in humans.

OBJECTIVE

The goal of this study was to study human GE180 from the perspective of the previous animal observations.

METHODS

With data from twenty-four participants having 18F-GE180 and 18F-AV45 PET scans, we evaluated the group differences of 18F-GE180 uptake between participants with and without cognitive impairment. An association analysis of 18F-GE180 and 18F-AV45 was then conducted to test if the relationship in humans is consistent with the two-stage association in AD mouse model.

RESULTS

Elevated 18F-GE180 was observed in participants with cognitive impairment compared to those with normal cognition. No regions showed reduced 18F-GE180 uptake. Consistent with mouse model, a two-stage association between 18F-GE180 and 18F-AV45 was observed.

CONCLUSIONS

18F-GE180 PET imaging showed promising utility in detecting pathological alterations in a symptomatic AD population. Consistent two-stage association between 18F-GE180 and amyloid PET in human and mouse suggested that 18F-GE180 uptake in human might be considerably influenced by microglial activation.

Continuing education in diversity and multicultural factors: Current state psychology board requirements and a call to action

Objective: A growing body of literature shows the unequivocal importance of incorporating diversity-related factors into the practice of clinical neuropsychology. Thus, it is imperative that we continue to seek and obtain updated training and knowledge on how culture and diversity intersect with our clinical roles throughout our careers, not merely to satisfy initial coursework requirements. Although most professional organizations pertaining to clinical psychology - and thereby neuropsychology - strongly encourage the pursuit of training in diversity-related factors, explicit requirements for such training across one's career are minimal. Method: The Asian Neuropsychological Association Advocacy Committee reviewed continuing education (CE) requirements for all US states. Results: We found that only 8 states mandated CE credits pertaining to diversity-related factors for the renewal of licensure. Discussion: Given how inseparable cultural competence is from any aspect of clinical work (and the harm that can be done if culture is not considered), it is essential that our field shift from aspirational guidance to firm requirements with regard to cultural competence and diversity-related training in psychology. Requiring CE units devoted to diversity-related factors represents one avenue to pursue this goal. This commentary outlines the current status of diversity-related CE for psychology licensure renewal and offers future directions for incorporating such training as a part of continuing professional development and education.

Inflammatory cytokine levels implicated in Alzheimer's disease moderate the effects of sex on verbal memory performance

Despite having an initial verbal memory advantage over men, women have greater rates of Alzheimer's disease and more rapid cognitive decline once diagnosed. Moreover, although Alzheimer's disease is influenced by inflammation, which itself has known sex differences, no study has investigated whether sex differences in memory are moderated by peripheral inflammatory activity. To address this issue, we analyzed data from 109 individuals (50 women, M_age = 71.62, range = 55-87) diagnosed as cognitively normal, or having mild cognitive impairment or Alzheimer's disease dementia. We then followed the sample for 12 months, as part of a longitudinal study of aging and Alzheimer's disease. At baseline, we assessed levels of the inflammatory cytokines interleukin (IL)-1β (IL-1β), IL-6, and tumor necrosis factor-α (TNF-α) in plasma. At baseline and 12 months, we assessed verbal memory using the Rey Auditory Verbal Learning Test and nonverbal memory using the Brief Visuospatial Memory Test-Revised. As hypothesized, for the full sample, women exhibited stronger verbal (but not nonverbal) memory than men. In women, but not men, higher IL-1β at baseline related to poorer verbal learning across both time points and delayed recall at 12 months. The effect of sex on memory also differed by IL-1β level, with women exhibiting a memory advantage both at baseline and 12 months, but only for those with low-to-moderate IL-1β levels. Therefore, high peripheral inflammation levels may lead to a sex-specific memory vulnerability relevant for Alzheimer's disease.

Prediabetes Is Associated With Brain Hypometabolism and Cognitive Decline in a Sex-Dependent Manner: A Longitudinal Study of Nondemented Older Adults

Although type 2 diabetes is a well-known risk factor for Alzheimer's disease (AD), little is known about how its precursor-prediabetes-impacts neuropsychological function and brain health. Thus, we examined the relationship between prediabetes and AD-related biological and cognitive/clinical markers in a well-characterized sample drawn from the Alzheimer's Disease Neuroimaging Initiative. Additionally, because women show higher rates of AD and generally more atherogenic lipid profiles than men, particularly in the context of diabetes, we examined whether sex moderates any observed associations. The total sample of 911 nondemented and non-diabetic participants [normal control = 540; mild cognitive impairment (MCI) = 371] included 391 prediabetic (fasting blood glucose: 100-125 mg/dL) and 520 normoglycemic individuals (age range: 55-91). Linear mixed effects models, adjusted for demographics and vascular and AD risk factors, examined the independent and interactive effects of prediabetes and sex on 2-6 year trajectories of FDG-PET measured cerebral metabolic glucose rate (CMRglu), hippocampal/intracranial volume ratio (HV/IV), cerebrospinal fluid phosphorylated tau-₁₈₁/amyloid-β_1-42 ratio (p-tau₁₈₁/Aβ_1-42), cognitive function (executive function, language, and episodic memory) and the development of dementia. Analyses were repeated in the MCI subsample. In the total sample, prediabetic status had an adverse effect on CMRglu across time regardless of sex, whereas prediabetes had an adverse effect on executive function across time in women only. Within the MCI subsample, prediabetic status was associated with lower CMRglu and poorer executive function and language performance across time within women, whereas these associations were not seen within men. In the total sample and MCI subsample, prediabetes did not relate to HV/IV, p-tau₁₈₁/Aβ_1-42, memory function or dementia risk regardless of sex; however, among incident dementia cases, prediabetic status related to earlier age of dementia onset in women but not in men. Results suggest that prediabetes may affect cognition through altered brain metabolism, and that women may be more vulnerable to the negative effects of glucose intolerance.

Objective subtle cognitive difficulties predict future amyloid accumulation and neurodegeneration

OBJECTIVE

To determine the temporal sequence of objectively defined subtle cognitive difficulties (Obj-SCD) in relation to amyloidosis and neurodegeneration, the current study examined the trajectories of amyloid PET and medial temporal neurodegeneration in participants with Obj-SCD relative to cognitively normal (CN) and mild cognitive impairment (MCI) groups.

METHOD

A total of 747 Alzheimer's Disease Neuroimaging Initiative participants (305 CN, 153 Obj-SCD, 289 MCI) underwent neuropsychological testing and serial amyloid PET and structural MRI examinations. Linear mixed effects models examined 4-year rate of change in cortical 18F-florbetapir PET, entorhinal cortex thickness, and hippocampal volume in those classified as Obj-SCD and MCI relative to CN.

RESULT

Amyloid accumulation was faster in the Obj-SCD group than in the CN group; the MCI and CN groups did not significantly differ from each other. The Obj-SCD and MCI groups both demonstrated faster entorhinal cortical thinning relative to the CN group; only the MCI group exhibited faster hippocampal atrophy than CN participants.

CONCLUSION

Relative to CN participants, Obj-SCD was associated with faster amyloid accumulation and selective vulnerability of entorhinal cortical thinning, whereas MCI was associated with faster entorhinal and hippocampal atrophy. Findings suggest that Obj-SCD, operationally defined using sensitive neuropsychological measures, can be identified prior to or during the preclinical stage of amyloid deposition. Further, consistent with the Braak neurofibrillary staging scheme, Obj-SCD status may track with early entorhinal pathologic changes, whereas MCI may track with more widespread medial temporal change. Thus, Obj-SCD may be a sensitive and noninvasive predictor of encroaching amyloidosis and neurodegeneration, prior to frank cognitive impairment associated with MCI.

Type 2 Diabetes Interacts With Alzheimer Disease Risk Factors to Predict Functional Decline

OBJECTIVE

The current study examined the interactive effect of type 2 diabetes and Alzheimer disease (AD) risk factors on the rate of functional decline in cognitively normal participants from the Alzheimer's Disease Neuroimaging Initiative.

METHODS

Participants underwent annual assessments that included the Functional Activities Questionnaire, an informant-rated measure of everyday functioning. Multilevel modeling, controlling for demographic variables and ischemic risk, examined the interactive effects of diabetes status (diabetes, n=69; no diabetes, n=744) and AD risk factors in the prediction of 5-year longitudinal change in everyday functioning. One model was run for each AD risk factor, including: objectively-defined subtle cognitive decline (Obj-SCD), and genetic susceptibility [apolipoprotein E ε4 (APOE ε4) as well as cerebrospinal fluid β-amyloid (Aβ), total tau (tau), and hyperphosphorylated tau (p-tau).

RESULTS

The 3-way diabetes×AD risk factor×time interaction predicted increased rates of functional decline in models that examined Obj-SCD, APOE ε4, tau, and p-tau positivity, but not Aβ positivity.

CONCLUSIONS

Participants with both diabetes and at least 1 AD risk factor (ie, Obj-SCD, APOE ε4, tau, and p-tau positivity) demonstrated faster functional decline compared with those without both risk factors (diabetes or AD). These findings have implications for early identification of, and perhaps earlier intervention for, diabetic individuals at risk for future functional difficulty.

MCI-to-normal reversion using neuropsychological criteria in the Alzheimer's Disease Neuroimaging Initiative

INTRODUCTION

The low mild cognitive impairment (MCI) to cognitively normal (CN) reversion rate in the Alzheimer's Disease Neuroimaging Initiative (2-3%) suggests the need to examine reversion by other means. We applied comprehensive neuropsychological criteria (NP criteria) to determine the resulting MCI to CN reversion rate.

METHODS

Participants with CN (n = 641) or MCI (n = 569) were classified at baseline and year 1 using NP criteria. Demographic, neuropsychological, and Alzheimer's disease biomarker variables as well as progression to dementia were examined across stable CN, reversion, and stable MCI groups.

RESULTS

NP criteria produced a one-year reversion rate of 15.8%. Reverters had demographics, Alzheimer's disease biomarkers, and risk-of-progression most similar to the stable CN group and showed the most improvement on neuropsychological measures from baseline to year 1.

DISCUSSION

NP criteria produced a reversion rate that is consistent with, albeit modestly improved from, reversion rates in meta-analyses. Reverters' biomarker profiles and progression rates suggest that NP criteria accurately tracked with underlying pathophysiologic status.

Characteristics of Adults With Unrecognized Hearing Loss

Purpose Early detection of hearing loss is important for providing support and intervention for adults with age-related hearing loss. However, many older adults have hearing loss that is unidentified. Because they do not present the problem at health care settings, there is a dearth of research on people with unrecognized hearing loss (URHL). This study elucidates differences between older adults with normal hearing, adults with recognized hearing loss (RHL), and adults with URHL. Method Participants included 130 adults, ages 55-85 years. Of these, 39 had hearing in the normal range (HNR), 61 had RHL, and 30 reported HNR but failed a hearing screen (i.e., URHL). Participants completed the Positive and Negative Affect Schedule (PANAS; Watson, Clark, & Tellegen, 1988 ) and a battery of neuropsychological tests. Results The URHL group reported more positive affectivity than the HNR and RHL groups on the PANAS. In addition, the URHL group was significantly older and more likely to be male compared to the HNR group. Importantly, age was not significantly correlated with PANAS. Positive affectivity accounted for unique variance in group membership even after accounting for age, gender, physical health, and cognitive health. Conclusions Older adults with URHL have more positive affectivity than older adults with HNR or RHL. This group may be prone to downplaying their difficulties; consequently, they may need to experience larger hearing deficits before seeking help. The findings highlight the need for research investigating the effectiveness of psychoeducation on the importance of formal hearing assessment verses relying on self-assessment in facilitating early and effective intervention among people with URHL.

Resilience and well-being after traumatic brain injury

Purpose: This study examined the extent to which resilience is associated with well-being outcomes after traumatic brain injury, and whether those relationships are independent of global personality traits, such as affectivity.Materials and methods: Sixty-seven adults with complicated-mild to severe traumatic brain injury participated. Measures included the Connor-Davidson Resilience Scale, Modified Cumulative Illness Rating Scale, Disability Rating Scale, SF-12 Health Survey, Satisfaction with Life Scale, and Community Integration Measure.Results: Objective physical health and disability showed modest relation to resilience, indicating that adverse health conditions and disability decreased with increasing resilience. The three measures of subjective well-being showed modest-to-strong positive relation to resilience. These correlations between resilience and well-being generally remained significant after accounting for negative and positive affectivity. Results also suggest that the influence of resilience on well-being has a threshold effect: a greater influence on outcome among people with low or inadequate resilience than among people with average or high resilience.Conclusion: The experience of brain injury does not diminish the positive influence resilience may have on long-term well-being. Resilience may function as a buffer to trauma even in the challenging context of cognitive insult. Routine assessment of resilience might be beneficial to the rehabilitation team.Implications for rehabilitationResilience is positively associated with subjective and objective well-being among adults with moderate-to-severe traumatic brain injury, and it appears to function among adults with traumatic brain injury similarly to adults without cognitive disabilities.Resilience overlaps with overarching trait personality constructs such as affectivity; yet, it has unique characteristics and unique value in understanding well-being.The adverse effects of low resilience show stronger influence on well-being than do the positive effects of high resilience.Routine assessment of resilience might be beneficial to the rehabilitation team in understanding patients and their families, especially in discharge planning, where beliefs about personal capabilities to rebound from adversity shape likely future behavior.

Artificially low mild cognitive impairment to normal reversion rate in the Alzheimer's Disease Neuroimaging Initiative

INTRODUCTION

We examined reasons for low mild cognitive impairment (MCI)-to-cognitively normal (CN) reversion rates in the Alzheimer's Disease Neuroimaging Initiative (ADNI).

METHODS

CN and MCI participants were identified as remaining stable, progressing, or reverting at 1-year of follow-up (Year 1). Application of ADNI's MCI criteria at Year 1 in addition to Alzheimer's disease biomarkers by group were examined.

RESULTS

The MCI-to-CN reversion rate was 3.0%. When specific components were examined, 22.5% of stable MCI participants had normal memory performance at Year 1 and their Alzheimer's disease biomarkers were consistent with the stable CN group. At Year 1, when all MCI criteria were not met, the more subjective Clinical Dementia Rating rather than objective memory measure appeared to drive continuation of the MCI diagnosis.

DISCUSSION

Results demonstrate an artificially low 1-year MCI-to-CN reversion rate in ADNI-diagnosed participants. If the Logical Memory cutoffs had been consistently applied, the reversion rate would have been at least 21.8%.

Neuropsychological Criteria for Mild Cognitive Impairment in the Framingham Heart Study's Old-Old

BACKGROUND/AIMS

Mild cognitive impairment (MCI) lacks a "gold standard" operational definition. The Jak/Bondi actuarial neuropsychological criteria for MCI are associated with improved diagnostic stability and prediction of progression to dementia compared to conventional MCI diagnostic approaches, although its utility in diagnosing MCI in old-old individuals (age 75+) is unknown. Therefore, we investigated the applicability of neuropsychological MCI criteria among old-old from the Framingham Heart Study.

METHODS

A total of 347 adults (ages 79-102) were classified as cognitively normal or MCI via Jak/Bondi and conventional Petersen/Winblad criteria, which differ on cutoffs for cognitive impairment and number of impaired scores required for a diagnosis. Cox models examined MCI status in predicting risk of progression to dementia.

RESULTS

MCI diagnosed by both the Jak/Bondi and Petersen/Winblad criteria was associated with incident dementia; however, when both criteria were included in the regression model together, only the Jak/Bondi criteria remained statistically significant. At follow-up, the Jak/Bondi criteria had a lower MCI-to-normal reversion rate than the Petersen/Winblad criteria.

CONCLUSIONS

Our findings are consistent with previous research on the Jak/Bondi criteria and support the use of a comprehensive neuropsychological diagnostic approach for MCI among old-old individuals.

Behavioral inhibition and activation systems in traumatic brain injury

PURPOSE/OBJECTIVE

Personality has been linked to cognitive appraisal and health outcomes; however, research specific to traumatic brain injury (TBI) has been sparse. Gray's theory of behavioral inhibition system and behavioral activation system (BIS/BAS) offers a neurobiologic view of personality that may be especially relevant to neurobehavioral change associated with TBI. The present study examined theoretical and psychometric issues of using the BIS/BAS scale among adults with TBI as well as BIS/BAS personality correlates of TBI. Research Method/Design: Eighty-one adults with complicated-mild to severe TBI and 76 of their significant others (SOs) participated. Measures included the BIS/BAS scale, Positive and Negative Affect Schedule, and Awareness Questionnaire.

RESULTS

Among adults with TBI, BIS/BAS internal consistency reliabilities were similar to those found in normative samples of adults without TBI. The TBI group endorsed significantly higher BAS than did the SO group, and injury severity was positively correlated to BAS. The SO group showed expected patterns of correlation between personality and affect; positive affect was associated with BAS, and negative affect with BIS. In contrast, in the TBI group, BAS was positively correlated to both positive and negative affect. Impaired awareness of abilities moderated the intensity of relationships between BIS/BAS and affect.

CONCLUSIONS/IMPLICATIONS

TBI was associated with relatively intensified BAS (approach behavior) but not BIS (avoidance behavior). The observed pattern is consistent with the neurobiology of TBI-related personality change and with theory regarding the independence of the BIS and BAS systems. The BIS/BAS scale shows promise as a personality measure in TBI. (PsycINFO Database Record

Mentalizing and motivation neural function during social interactions in autism spectrum disorders

Autism Spectrum Disorders (ASDs) are characterized by core deficits in social functions. Two theories have been suggested to explain these deficits: mind-blindness theory posits impaired mentalizing processes (i.e. decreased ability for establishing a representation of others' state of mind), while social motivation theory proposes that diminished reward value for social information leads to reduced social attention, social interactions, and social learning. Mentalizing and motivation are integral to typical social interactions, and neuroimaging evidence points to independent brain networks that support these processes in healthy individuals. However, the simultaneous function of these networks has not been explored in individuals with ASDs. We used a social, interactive fMRI task, the Domino game, to explore mentalizing- and motivation-related brain activation during a well-defined interval where participants respond to rewards or punishments (i.e. motivation) and concurrently process information about their opponent's potential next actions (i.e. mentalizing). Thirteen individuals with high-functioning ASDs, ages 12-24, and 14 healthy controls played fMRI Domino games against a computer-opponent and separately, what they were led to believe was a human-opponent. Results showed that while individuals with ASDs understood the game rules and played similarly to controls, they showed diminished neural activity during the human-opponent runs only (i.e. in a social context) in bilateral middle temporal gyrus (MTG) during mentalizing and right Nucleus Accumbens (NAcc) during reward-related motivation (Pcluster < 0.05 FWE). Importantly, deficits were not observed in these areas when playing against a computer-opponent or in areas related to motor and visual processes. These results demonstrate that while MTG and NAcc, which are critical structures in the mentalizing and motivation networks, respectively, activate normally in a non-social context, they fail to respond in an otherwise identical social context in ASD compared to controls. We discuss implications to both the mind-blindness and social motivation theories of ASD and the importance of social context in research and treatment protocols.

Differential retinal angiogenic response to sustained intravitreal release of VEGF and bFGF in different pigmented rabbit breeds

PURPOSE

To determine if two different breeds of pigmented rabbits can demonstrate differences in the degree of inducible angiogenesis within the retina.

METHODS

Non-biodegradable Hydron pellets approximately 1.5 mm in diameter containing both vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) were implanted intravitreally over the optic disk of either Dutch belt rabbits or New Zealand White/Black satin cross rabbits. Control animals from both groups were implanted with blank Hydron pellets. Animals were examined periodically over a 30-day period following implantation. Results were documented by fundus photography and flourescein angiography. Stages of neovascularization (NV) were graded between +1 (preproliferative) and +4 (total NV) with +5 for NV complicated by hemorrhage and/or retinal detachment.

RESULTS

The angiogenic response in the retinas of pigmented NZW/Black satin cross rabbits (N = 5) following implantation of VEGF/bFGF-containing pellets varied extensively from the Dutch belt animals (N = 7). In the Dutch belt rabbits, grading of the angiogenic response demonstrated either +4 or +5 between day 20 and day 30 after implantation. In contrast, the NZW/Black satin cross animals gave a more muted response with a maximum grade of +2 following exposure to the same amount of VEGF and bFGF. Control eyes that received only blank pellets showed no evidence of retinal NV in either the Dutch belts (N = 5) or the NZW/Black satin cross rabbits (N = 5). Statistical analysis showed a significant interaction effect for breed and pellet type (F = 44.85 with 1 df, p < 0.00005), indicating a difference between the breeds in the angiogenic response to the pellet. Moreover, both the NZW/BSC and Dutch belt rabbits displayed a significant increase in angiogenesis with the VEGF/bFGF pellet in comparison to the blank pellet (p = 0.037 and p < 0.00005, respectively).

CONCLUSIONS

These studies indicate that two different breeds of pigmented rabbits exhibit different angiogenic responses to the same amount of both VEGF and bFGF. Florid retinal NV leading to hemorrhage, fibrovascular membrane formation, and traction retinal detachment occurred in the Dutch belt rabbits while tortuosity and dilatation of existing blood vessels with subsequent regression occurred in the NZW/Black satin cross animals. Such differences in the angio-genic response may be due to differences in the genetic background of these animals. If genetic heteriogeneity exists for angiogenic responses, then understanding the genetic role in the regulation of angiogenesis will lead to the design of more effective anti-angiogenic agents and can provide predictive outcomes of individual responses to therapy.

Prospective study of 125 cases of Staphylococcus aureus bacteremia in children in New Zealand

BACKGROUND

Staphylococcus aureus bacteremia is a common complication of S. aureus infection. There are few pediatric studies defining the incidence and associated morbidity and mortality of S. aureus bacteremia and no such New Zealand studies. We conducted a prospective study of S. aureus bacteremia in children in New Zealand.

METHODS

From July 1, 1996 to December 31, 1998, we included all children < 16 years of age with S. aureus bacteremia in Auckland and Christchurch. Relevant information regarding patient demographics, clinical course and outcome and laboratory results was recorded.

RESULTS

One hundred twenty-five cases of true S. aureus bacteremia were identified. There were 4 deaths within 30 days of the onset of bacteremia. Fourteen (11%) of the children were < 1 month of age. Maori children (relative risk, 2.0; 95% confidence interval, 1.3 to 3.2) were twice as likely and Pacific Island children (relative risk, 2.5; 95% confidence interval, 1.6 to 3.8) 2.5 times as likely as white children to acquire S. aureus bacteremia. The peak incidence of S. aureus bacteremia was observed in Pacific Island children < 1 year of age (105 cases/100,000 children/year). Twenty-seven percent of cases were related to intravenous catheters. Seventy percent of cases were community-acquired. Ninety-eight percent of non-catheter-related cases in children > 1 month of age were community-acquired. There was a low rate of methicillin resistance (6%).

CONCLUSIONS

S. aureus bacteremia is largely community-acquired in children in New Zealand and is more common in Pacific Island and Maori populations. Although there is a low associated mortality, a significant number are potentially preventable cases secondary to intravenous catheters.

Pneumococcal bacteraemia and opportunities for prevention

AIMS

Despite availability of active antimicrobial agents for its treatment, the mortality from pneumococcal bacteraemia (PB) may reach 30% to 40% in high-risk groups. Greater vaccine use may reduce the incidence of PB. The aim of this study was to determine the proportion of patients with PB who had indications for, but had not received, pneumococcal vaccination.

METHODS

From December 1998 to March 2000, all episodes of PB in adults in four Auckland hospitals were followed prospectively. Underlying disease, outcome, and pneumococcal vaccination history were recorded.

RESULTS

96 patients had PB: the median age was 63 years, range 16 to 93 years. 42 (44%) were > or = 65 years. The relative risk (RR) of acquiring PB for Maori and Pacific Island people was more than two times that of both European and other ethnic groups: RR 2.3 (95% CI 1.5 - 3.6) and 2.4 (1.6 - 3.8), respectively. The most common presentation was pneumonia; 84 (88%), of which 74 (88%) were community acquired. Five (5%) patients had meningitis. The overall mortality was 18%. Eleven (11%) pneumococcal isolates had intermediate susceptibility to penicillin and six (6%) were resistant. 69 (72%) patients had one or more condition for which pneumococcal vaccination is recommended but only two (2%) patients had received it. 82 (85%) patients were infected with serotypes included in the current pneumococcal vaccine.

CONCLUSIONS

Most adult patients with PB have underlying medical conditions for which vaccination is recommended but only rare patients get vaccinated. Emerging antimicrobial resistance is a further incentive to increase the use of pneumococcal vaccination. Greater use of pneumococcal vaccine will probably require a change in its funding status, similar to the current policy for influenza vaccine. It may also be appropriate to consider targeted use of the vaccine in Maori and Pacific Island people given their higher rates of disease.

Prospective study of 424 cases of Staphylococcus aureus bacteraemia: determination of factors affecting incidence and mortality

BACKGROUND

Staphylococcus aureus bacteraemia (SAB) is a common complication of S. aureus infection and is associated with a high mortality.

AIMS

To document prospectively the pattern of illness associated with SAB in New Zealand and, by recording patient demographic factors and clinical features, to identify risk factors associated with a poor outcome.

METHODS

From 1 July 1996 to 31 December 1997, adults with SAB were prospectively studied in six tertiary care hospitals. All information obtained from patients' records was recorded on worksheets and transferred to a computerized spreadsheet for analysis.

RESULTS

There were 424 patients with SAB. Maori (relative risk (RR)= 1.8, 95% confidence interval (CI) = 1.3-2.6) and Pacific Island people (RR = 4.0, 95% CI = 3.1-5.3) were significantly more likely than people of European descent to acquire SAB, but not to die from the infection. Fifty per cent of cases were community acquired. A source was identified for 85%: intravenous catheter (31%), primarily hospital acquired, and skin/soft tissue (22%), primarily community acquired, were the most common foci. The 30-day mortality was 19%, 83% of whom died within 2 weeks. Risk factors for a poor outcome were: increasing age above 60, female sex (RR = 1.4, 95% CI = 1.0-2.1), diabetes mellitus (RR = 1.5, 95% CI = 1.0-2.4), immunosuppression (RR = 1.5, 95% CI = 1.0-2.4), pre-existing renal impairment (RR = 1.8, 95% CI = 1.2-2.7), malignancy (RR= 2.2, 95% CI = 1.4-3.5), lung as a source (RR = 2.8, 95% CI = 1.9-4.2) and unknown source (RR = 2.3, 95% CI = 1.5-3.3). Mortality was also accurately predicted by two multifactor scoring systems. There was a low rate of methicillin resistance (5%).

CONCLUSIONS

Staphylococcus aureus bacteraemia is more likely to occur in certain ethnic groups, while mortality is associated with other identifiable risk factors and continues to be high. Intravenous catheters remain the most common and most preventable cause of SAB.

Localization of the human mGluR4 gene within an epilepsy susceptibility locus(1)

The family of metabotropic glutamate receptors (mGluRs) consists of eight homologous G-protein coupled receptors. Several of the mGluRs, including the mGluR4 receptor subtype, are localized presynaptically; activation of this receptor induces an inhibition of neurotransmitter release from nerve terminals. Disruption of the mGluR4 gene in mice results in impaired motor and spatial learning, and alterations in seizure susceptibility. In this study, we have determined the structure of the human mGluR4 gene, as well as its chromosomal localization. A comparison of the gene structure of mGluR4 with the highly homologous mGluR6 receptor subtype reveals that both of the genes contain ten exons with similar exon/intron boundaries. A refined localization of mGluR4 was carried out by constructing a bacterial artificial chromosome clone contig of the region surrounding the gene. Thirteen sequence tagged sites (STSs) were identified within this contig. The gene was localized to chromosome 6 band p21.3 by fluorescence in situ hybridization (FISH). The mapping of the mGluR4 gene indicates that it is approximately 1 megabases centromeric of the major histocompatibility complex and 5 megabase from the GABA(B)R1 gene. The mGluR4 gene also falls within a susceptibility locus for juvenile myoclonic epilepsy suggesting a potential link to this form of epilepsy.

Intravitreal VEGF and bFGF produce florid retinal neovascularization and hemorrhage in the rabbit

PURPOSE

Vascular endothelial growth factor (VEGF) causes widespread retinal vascular dilation, produces breakdown of the blood-retinal barrier, and is implicated in ocular neovascularization (NV). Basic fibroblast growth factor (bFGF) also has been implicated in the production of ocular NV. This study was performed to investigate the ability of simultaneous sustained intravitreal release of both VEGF and bFGF to induce robust retinal NV in the rabbit.

METHODS

Intravitreal implantation of sustained-release Hydron polymeric pellets containing both 20 microg of VEGF and 20 microg of bFGF was performed on adult male Dutch belted rabbits. In other animals either 20 microg or 50 microg bFGF-containing pellets was implanted intravitreally; also, either 20 microg VEGF or 50 microg VEGF-containing pellets was implanted. Control rabbits received either blank polymeric pellets or a pellet containing 30 microg bovine serum albumin. Eyes were examined by indirect ophthalmoscopy after surgery at 24 hrs, 48 hrs, 4 days, 7 days, 14 days, 21 days, and 28 days. Findings were documented by color fundus photography and fluorescein angiography (FA). Eyes were enucleated and prepared for histologic analysis at 28 days following intravitreal implantation of the VEGF/bFGF-containing pellets.

RESULTS

In all eyes implanted with VEGF/bFGF pellets, dilation and tortuosity of existing blood vessels were observed within 48 hrs after pellet implantation. The progression of retinal vascular changes was rapid and occurred over the entire optic disk and medullary rays between 4 and 7 days. Hemorrhage occurred as early as 14 days after VEGF/bFGF pellet implantation. In eyes with massive hemorrhage, total traction retinal detachment developed after the second week. The presence of abnormal tissues at the vitreo-retinal interface within 28 days was demonstrated by light microscopy while FA showed profuse leakage of dye from anomalous vessels within the first week. Neither bFGF-exposed eyes nor control eyes showed any vascular changes. Eyes that received only VEGF-containing pellets exhibited tortuosity of existing vessels, but neither hemorrhaging nor retinal detachment occurred.

CONCLUSIONS

These results demonstrate that retinal vascular changes leading to hemorrhaging is produced rapidly in the rabbit by simultaneous intravitreal release of both VEGF and bFGF. Understanding how these growth factors induce retinal NV may suggest novel therapeutic treatment strategies.

Surveillance for antimicrobial resistance in enterococci

AIM

To describe antimicrobial resistance patterns of Enterococcus species in Auckland.

BACKGROUND

Antimicrobial resistant enterococci have emerged as major nosocomial pathogens in overseas hospitals. It is recommended that hospitals perform periodic surveys to determine local enterococcal resistance patterns.

METHODS

Enterococcal isolates from four patient groups were tested: group I were recovered from routine clinical specimens; group II were stool isolates from patients at risk of having vancomycin resistant enterococci, eg, intensive care unit patients, patients receiving vancomycin, and immunocompromised patients receiving antibiotics; group III were enterococci from stool specimens sent for Clostridium difficile toxin testing; group IV were isolates from stool specimens submitted to a community laboratory for enteric pathogen testing. All enterococci isolated were tested for the presence of beta-lactamase, susceptibility to amoxycillin, teicoplanin, vancomycin, and for high level gentamicin and streptomycin resistance.

RESULTS

There were 121 group I enterococcal isolates. 628 stool specimens were cultured. Enterococci were isolated from: 76/148 (51%) group II specimens; 166/279 (60%) group III specimens; and 70/201 (35%) of group IV specimens. Antimicrobial susceptibility testing was performed on 433 isolates; 74% were E faecalis, 12% E faecium, 6% E gallinarum/casseliflavus group and 8% other enterococcal species. No isolate produced beta-lactamase. All E faecalis were susceptible to amoxycillin. Two E faecium and one enterococcus species were resistant to amoxycillin (MICs all 16 mg/L). All isolates were susceptible to teicoplanin. Fourteen E gallinarum/casseliflavus group isolates had intermediate susceptibility to vancomycin (MICs of 8 mg/L). One E faecium had intermediate susceptibility to vancomycin (MIC 8 mg/L). High level gentamicin and streptomycin resistance occurred in 64 (15%) and 50 (12%) isolates respectively.

CONCLUSION

Vancomycin resistance is rare and is essentially restricted to species that are rarely clinical pathogens, i.e., E casseliflavus and E gallinarum. Our results have established the local susceptibility profile for enterococcal isolates. This allows comparison with other locations and the detection of emerging trends of resistance.

Chronic inhalation exposure to ozone and nitric acid elevates stress-inducible heat shock protein 70 in the rat lung

The ability of urban oxidant and acid air pollutants to induce heat shock proteins (HSPs) in the mammalian lung is not known. Such proteins are known to be correlated with environmental stress and pathophysiological conditions. In this study, stress-inducible HSP 70 was assessed by slot-blotting in rat lungs (N=10 per group) following inhalation exposures for 4 h per day, 3 days per week for 40 weeks to the following pollutants: (a) purified air;(b) 0.15 ppm ozone (O3);(c)50 micrograms/m3 nitric acid (HNO3); or(d) a combination of both 0.15 ppm O3 and 50 micrograms/m3 HNO3. At 24 h following the last exposure, samples from the right apical lobe of the lung were obtained for either slot-blotting or gel electrophoretic separation, subsequent protein immunoblotting, and chemiluminescence detection of HSP 70 levels. Experiments demonstrate that stress-inducible HSP 70 was present constitutively in the control lungs and was separable from the constitutive form of HSP 70. Slot-blotting analysis demonstrate that the O3 and HNO3 exposures alone produced significant elevations of HSP70. Specifically, either O3 or HNO3 alone significantly elevated lung stress-inducible HSP 70 levels by 277% and 221% respectively, above control levels. The group exposed to combined O3 and HNO3 showed a 177% elevation in lung stress-inducible HSP 70 that was significantly greater that the group inhaling purified air, but this effect was less than the effects of either pollutant component alone. Moreover, all exposure groups were significantly different from one another. These results indicate that stress-inducible HSP 70 in the rat lung is highly elevated after chronic inhalation exposures to both O3 and HNO3 when administered either alone or in combination within the range of urban ambient concentrations.

Melatonin inhibits the proliferation of retinal pigment epithelial (RPE) cells in vitro

The possible antiproliferative effect of melatonin on retinal pigment epithelial (RPE) cells in vitro was investigated. Bovine RPE cells cultured in Ham's F12 medium supplemented with 10% fetal bovine serum had a nuclear density of 73.6 +/- 6.1 nuclei/mm2 at 72 h after seeding. The nuclear density at this time-point was doubled if either 50 or 100 ng/ml human epidermal growth factors (hEGF) was added to the culture medium. When these hEGF-stimulated cells were treated with melatonin from 10 to 500 pg/ml, the proliferation was suppressed with a dose-response relationship. At 250 and 500 pg/ml melatonin, the nuclear densities of the melatonin-treated cells were similar to those of the control cells. Using mitotically active SV-40 transformed human fetal RPE cells cultured in a serum-free medium, melatonin was also shown to be antiproliferative. In the presence of 500 pg/ml melatonin, the proliferation of these cells was inhibited to 77% as compared to the control. These results were further supported by the reduced [H3]thymidine uptake in the melatonin-treated cells. We propose that melatonin, at physiologic concentrations, has an antiproliferative effect, and that cultured RPE cells stimulated to proliferate by either hEGF treatment or SV-40 transfection are responsive to melatonin. Melatonin may either inhibit mitosis in actively dividing cells or modulate hEGF action.

Induction of stress proteins in SV-40 transformed human RPE-derived cells by organic oxidants

The expression and induction of heat shock proteins (HSPs) were examined in cultured SV-40-transformed human retinal pigment epithelial (RPE)-derived cells following exposure to chemical oxidants. Concentrations of hydrogen peroxide and the organic oxidants tert-butyl hydroperoxide, cumene hydroperoxide and linoleic acid hydroperoxide were used under conditions where cell viability was between 75% and 90% as determined by the trypan blue exclusion tests. The types of HSPs that are either induced and/or elevated from constitutive levels in cultured transformed cells were separated both by SDS-PAGE and by two-dimensional gel electrophoresis. Subsequent immunoblotting was performed with both a monoclonal antibody (MAb C92) specific for only the stress-inducible form of HSP 70, namely HSP 72, and with a monoclonal antibody (MAb N27) specific for both the stress-inducible HSP 72 and its constitutive form, HSP 73. As positive controls for comparison, other types of stressing agents were used that included heat shock at 41 degrees C for various times and exposure to the proline analogue, azetidine-2-carboxylic acid (AzC). Protein immunoblotting analysis demonstrate that: (a) Stress-inducible HSP 72 is present at low levels in non-stressed cultured transformed RPE-derived cells and in fresh bovine retina and RPE, but is not detectable in non-stressed cultured lung fibroblasts until induction with heat shock; and (b) Stress-inducible HSP 72 is elevated from constitutive levels in RPE-derived cultured cells after exposure to various oxidants. After cellular exposure to both organic oxidants and to AzC in the presence of L-[35-S]-methionine, two-dimensional gel electrophoresis confirmed the elevation of newly synthesized HSP 72. Thus, these results indicate that cultured human SV-40-transformed RPE-derived cells are capable of elevated HSP 72 biosynthesis under conditions of oxidative stress produced by organic oxidants.

Induction of stress proteins in cultured human RPE-derived cells

The expression and induction of stress protein families were examined in cultured human fetal retinal pigment epithelial (RPE)-derived cells. These stress proteins (SPs) include the heat-shock proteins (HSPs) that have been shown to be highly inducible following treatment by heat, amino acid analogues, and various chemical oxidants. Three sets of proteins with molecular weights of 70, 84, and 110 kilodaltons were elevated simultaneously from constitutive levels after treatment with azetidine-2-carboxylic acid (AzC), an amino acid analogue of proline. Further experiments demonstrated that incubation of cultured human fetal RPE-derived cells with hydrogen peroxide (H2O2) at concentrations ranging from 10(-5) M to 10(-3) M for 30 minutes to 60 minutes did not elevate the levels of the common families of HSPs as with AzC. These results indicate that cultured human fetal RPE-derived cells are capable of elevated HSP biosynthesis after AzC exposure but appear resistant to H2O2 treatment.

Applicability of the Chinese Beck Depression Inventory

Using a sample of 329 currently depressed patients from 24 hospitals across China, this study assesses the reliability and validity of the Chinese version of Beck Depression Inventory (CBDI). Even though the internal reliability and the concurrent validity were good (Cronbach alpha = 0.846; r = 0.566), the results showed that the item of Loss of Libido was most weakly correlated with the CBDI's total score; the items of Sense of Punishment, Sense of Hate, Self Accusations, Crying Spells, Irritability, and Somatic Preoccupation were poorly associated with the intensity of depression measured by the total score of the Chinese version of Hamilton Depression Rating Scale (CHDS). The CBDI's construct validity was rather poor by principal component analysis: three of six factors were unexplainable in terms of clinical features of depression. The results demonstrated that CBDI, even though it was semantically translated into Chinese language, still could not be effectively applied in clinic and research settings in China. Using the theory and methods of psychometrics to develop China's own culturally sensitive self-report inventory is the correct way to eliminate cultural bias and make cross-cultural research more valid. This is the most rigorous scientific approach to cross-cultural comparisons.

Ornithine decarboxylase activity in rabbit retina following treatment with alpha-difluoromethylornithine

The rabbit retina has been utilized as a model for the study of abnormal cellular proliferation on the retinal surface and into the vitreous, a process commonly initiated by trauma and generally leading to retinal detachment. This study characterizes the ability of alpha-difluoromethylornithine (alpha-DFMO), a suicide inactivator of L-ornithine decarboxylase (EC 4.1.1.17) to inactivate normal retinal ornithine decarboxylase (ODC) activity in the crude supernatant fraction after incubation with different concentrations of alpha-DFMO and at various times after intraocular administration. Partial inactivation of ODC activity occurred following preincubation of crude retinal supernatant fraction with 10(-5) M alpha-DFMO (N = 3; 34 +/- 6.9% of control), whereas preincubation with 10(-8) M alpha-DFMO did not alter ODC activity significantly (N = 3; 94 +/- 2% of control). Different concentrations of alpha-DFMO administered intraocularly inactivated retinal ODC activity to varying degrees with different rates of recovery. No gross toxicity occurred with ocular tissues following intravitreal administration of alpha-DFMO as determined by electrophysiologic measurements, by indirect examination of the retina, and by measurement of intraocular pressure. These results suggest that alpha-DFMO may be a useful tool in which to define the physiologic role of ODC and polyamines in intraocular cellular proliferative diseases.

Intranuclear rodlets in the rabbit retina following treatment with MPTP

Retinas from pigmented rabbits treated with N-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP, a chemical inducer of Parkinsonism in man and monkeys) were studied using light- and electron microscopy. The nuclei of many cells in the inner nuclear layer and the ganglion cell layer of the treated retinas contained crystalloids (intranuclear rodlets) of varying length (0.5-8 microns) which were composed of bundles of 12 nm filaments and which were seen only rarely in untreated retinas. The induced rodlets are oval to round cylinders, 15-20 filaments across (although they are smaller in untreated retinas). Similar intranuclear inclusions have been described under varying conditions in neurons and glia in the central nervous system of several animal species. In rabbits injected acutely with MPTP, most of the affected cells are in the inner nuclear layer in the position of bipolar cells, while in the chronically injected animals, clearly identifiable amacrine cells, and the nuclei of some cells in the ganglion cell layer also contained the inclusions. Evidence is presented that the rodlet-containing cells in the ganglion cell layer include both ganglion cells and displaced amacrine cells. These anatomic findings are relevant to understanding the physiological and biochemical effects of the drug on the retina which we reported previously (Wong, Ishibashi, Tucker and Hamasaki, 1985).

Ornithine decarboxylase activity during formation of experimental epiretinal membranes

This study demonstrates in a rabbit model of epiretinal membrane formation that retinal-associated ODC activity increases during this pathological process. These changes in retinal-associated ODC activity most likely occur in relationship to the proliferative lesion itself, since the retina consists primarily of nonproliferative tissues. Further knowledge of intraocular polyamine metabolism during epiretinal membrane formation which can result in retinal detachment may lead to the development of an effective pharmacological treatment.

Consequences of ornithine decarboxylase inactivation by alpha-difluoromethylornithine and 5-fluorouracil on the growth of rabbit fibroblasts

The role of ornithine decarboxylase and polyamines in proliferative vitreoretinopathy (PVR) is ill-defined. An increase in the activity of this enzyme concurrent with an increase in polyamine levels may be essential in the process of intraocular cellular proliferation. Therefore, in this study, cultured rabbit fibroblasts were exposed to DL-alpha-difluoromethylornithine (alpha-DFMO), a mechanism-based irreversible inactivator of ornithine decarboxylase, alone and in combination with 5-fluorouracil (5-FU). Concentrations of 0.1mM alpha-DFMO and 0.125mM 5-FU decreased rabbit fibroblast cell number by 60% and 65%, respectively, after three days, while with either 5.0mM alpha-DFMO or 0.25mM 5-FU, cell number is decreased by 95%. The effectiveness of inhibitory concentrations of 5-FU and alpha-DFMO together in reducing cell number is additive.

Inhibitors of inosinic acid dehydrogenase. 2-Substituted inosinic acids

A series of 2-substituted inosine monophosphate (IMP) and inosine derivatives were synthesized and tested for inhibitory activity against IMP dehydrogenase from Escherichia coli. All of the IMP analogues that possessed electron-withdrawing substituents on the phenyl ring of a benzylthio group placed at the 2-position of IMP showed strong inhibition, which was competitive with IMP. No evidence of hydrophobic interactions of the 2-substituent with the enzyme was observed.

Specific reaction of 9-cis-retinoyl fluoride with bovine opsin

Opsin readily undergoes Schiff base formation between an active site lysine and 9-cis- or 11-cis-retinaldehyde to form the visual pigments isorhodopsin (lambda max = 487 nm) and rhodopsin (lambda max = 500 nm), respectively (Dratz, 1977). It would be predicted that 9-cis-retinoyl fluoride (1), an isostere of 9-cis-retinal, should be an active site directed, mechanism-based labeling agent of opsin, since a stable peptide bond should be formed instead of a Schiff base. It is shown here that 9-cis-retinoyl fluoride (1) reacts with opsin in a time-dependent fashion (t1/2 = 9 min at 25 microM 1) to form a new, nonbleachable pigment with a lambda max of approximately 365 nm. beta-Ionone competitively slows down the rate of the reaction. The absorbance of the new pigment at approximately 365 nm is similar to that of model amide compounds. This result is consistent in a general and qualitative way with the Nakanishi-Honig point-charge model for visual pigments which requires that the chromophore be charged, a situation not possible when the retinoid is linked to opsin via a peptide bond rather than a protonated Schiff base [Honig, B., Dinur, U., Nakanishi, K., Balogh-Nair, V., Gawinowicz, M.A., Arnabaldi, M., & Motto, M.G. (1979) J. Am. Chem. Soc. 101, 7084-7086]. 9-cis-Retinoyl fluoride (1) is approximately 4-fold more potent than all-trans-retinoyl fluoride (2) as an inactivator of bovine opsin. Importantly, 13-cis-retinoyl fluoride (3) is inactive, and no new absorption band at 365 nm is observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic ganglioside abnormalities in a patient with familial erythrophagocytic lymphohistiocytosis

Familial erythrophagocytic lymphohistiocytosis (FEL) is an autosomal recessive disease of unknown pathogenesis. Because of evidence of increased circulating and hepatic lipids in FEL, we performed a comprehensive analysis of the hepatic lipids of a patient with this disease. In contrast to normal qualitative characteristics and to normal or only mildly elevated concentrations of total lipids, neutral lipids, phospholipids, and neutral glycosphingolipids, this study reports a significant elevation of acidic glycosphingolipids, gangliosides (387 versus 147 nmole lipid-bound sialic acid/g wet weight, patient versus control). This quantitative abnormality was unusual in that it included disproportionately increased concentrations of most of the minor hepatic ganglioside species rather than either a marked increase in one single or a generalized nonspecific increase in all gangliosides, which is characteristic of known disorders exhibiting hepatic ganglioside storage. Activities of the hepatic lysosomal glycosylhydrolases which are important in ganglioside metabolism were therefore assessed by using artificial substrates. Of the enzymes tested, beta-galactosidase activity alone was remarkable, being moderately reduced (33% of that of the normal liver); no biochemical explanation for the reduction was found. The findings suggest FEL may be associated with a unique quantitative and qualitative abnormality in hepatic gangliosides, the cause of which remains to be elucidated.

Retention of gangliosides in serum delipidated by diisopropyl ether-1-butanol extraction

Extraction with diisopropyl ether-1-butanol is a rapid method for the delipidation of serum without protein denaturation. We sought to confirm that this solvent system would also extract the highly polar acidic glycosphingolipids, gangliosides. In fact, however, both endogenous serum gangliosides and radiolabeled rat brain gangliosides added to serum were nearly quantitatively retained (87.5% and 98.7%, respectively) in the aqueous phase after two extractions. Therefore, while useful for the extraction of most lipids, this delipidation procedure cannot be used to remove gangliosides from serum or plasma.