A systematic review of older adults' request for or attitude toward euthanasia or assisted-suicide

OBJECTIVES

Prevalence rates of death by euthanasia (EUT) and physician-assisted suicide (PAS) have increased among older adults, and public debates on these practices are still taking place. In this context, it seemed important to conduct a systematic review of the predictors (demographic, physical health, psychological, social, quality of life, religious, or existential) associated with attitudes toward, wishes and requests for, as well as death by EUT/PAS among individuals aged 60 years and over.

METHOD

The search for quantitative studies in PsycINFO and MEDLINE databases was conducted three times from February 2016 until April 2018. Articles of probable relevance (n = 327) were assessed for eligibility. Studies that only presented descriptive data (n = 306) were excluded.

RESULTS

This review identified 21 studies with predictive analyses, but in only 4 did older adults face actual end-of-life decisions. Most studies (17) investigated attitudes toward EUT/PAS (9 through hypothetical scenarios). Younger age, lower religiosity, higher education, and higher socio-economic status were the most consistent predictors of endorsement of EUT/PAS. Findings were heterogeneous with regard to physical health, psychological, and social factors. Findings were difficult to compare across studies because of the variety of sample characteristics and outcomes measures.

CONCLUSION

Future studies should adopt common and explicit definitions of EUT/PAS, as well as research designs (e.g. mixed longitudinal) that allow for better consideration of personal, social, and cultural factors, and their interplay, on EUT/PAS decisions.

Towards blood flow in the virtual human: efficient self-coupling of HemeLB

Many scientific and medical researchers are working towards the creation of a virtual human—a personalized digital copy of an individual—that will assist in a patient’s diagnosis, treatment and recovery. The complex nature of living systems means that the development of this remains a major challenge. We describe progress in enabling the HemeLB lattice Boltzmann code to simulate 3D macroscopic blood flow on a full human scale. Significant developments in memory management and load balancing allow near linear scaling performance of the code on hundreds of thousands of computer cores. Integral to the construction of a virtual human, we also outline the implementation of a self-coupling strategy for HemeLB. This allows simultaneous simulation of arterial and venous vascular trees based on human-specific geometries.

A Cross-Sectoral Comparison of Prevalence and Predictors of Symptoms of Depression Over Time Among Older Adults in Ontario, Canada

OBJECTIVES

Late-life depression, a common mental health issue, poses a significant burden of illness globally. We investigated factors associated with symptoms of depression among older adults across 3 health sectors in Ontario, Canada.

METHOD

Electronic health assessment data on older adults aged 60 years+ in home care (HC; N = 359 217), long-term care (LTC; N = 125 496), and palliative care (PC; N = 29 934) were examined. Change in symptoms of depression, measured using the interRAI Depression Rating Scale (DRS), over time was examined, including predictors of the development of depression.

RESULTS

At baseline, symptoms of depression were observed in 19.1% (HC), 24.2% (LTC), and 11.9% (PC). This increased to 20.6% (HC), 33.8% (LTC), and 13.2% (PC) at follow-up. For most older adults, DRS scores remained the same across sectors over time. Three independent variables emerged consistently across sectors as the main risk and protective factors for symptoms of depression.

CONCLUSION

Although variations in the risk and protective factors for late-life depression were demonstrated across each sector, some commonalities emerged including unmanaged pain, symptoms of depression at baseline, social connectedness, and activity.

Clinical characteristics and patterns of health deficits of centenarians receiving home care and long-term care services

Centenarians (persons aged 100years and older) are one of the fastest growing cohorts in countries across the world. With the increasing prevalence of centenarians and growing amount of clinical information in large administrative health databases, it is now possible to more fully characterize the health of this unique and heterogeneous population. This study described patterns of health deficits in the centenarian population receiving care from community-based home care services and long-term care facilities (LTCFs) in Ontario, Canada. All centenarians who received home care and were assessed using the interRAI-Home Care Assessment instrument between 2007 and 2011 (n=1163) and all centenarians who resided in LTCFs between 2005 and 2011 who were assessed using the interRAI Minimum Data Set (MDS 2.0) (n=2228) were included in this study. Bivariate analyses described the centenarian population while K-means clustering analyses were utilized to identify relatively homogeneous subgroups within this heterogeneous population. The 3391 centenarians were aged 100 to 114 (mean age 101.5years ±1.9 SD) and the majority were women (84.7%). Commonly reported deficits included cognitive impairment, physical impairment, and bladder problems. Centenarians residing in LTCFs were significantly more likely than centenarians receiving home care services to report cognitive or functional impairment, or to exhibit symptoms of depression. The commonalities and uniqueness of four clusters of centenarians are described. Although there is great variability, there is also commonality within the centenarian population. Recognizing patterns within the heterogeneity of centenarians is key to providing high-quality person-centered care and to targeting health promotion and intervention strategies.

Novel hyperthermia applicator system allows adaptive treatment planning: Preliminary clinical results in tumour-bearing animals

Hyperthermia (HT) as an adjuvant to radiation therapy (RT) is a multimodality treatment method to enhance therapeutic efficacy in different tumours. High demands are placed on the hardware and treatment planning software to guarantee adequately planned and applied HT treatments. The aim of this prospective study was to determine the effectiveness and safety of the novel HT system in tumour-bearing dogs and cats in terms of local response and toxicity as well as to compare planned with actual achieved data during heating. A novel applicator with a flexible number of elements and integrated closed-loop temperature feedback control system, and a tool for patient-specific treatment planning were used in a combined thermoradiotherapy protocol. Good agreement between predictions from planning and clinical outcome was found in 7 of 8 cases. Effective HT treatments were planned and verified with the novel system and provided improved quality of life in all but 1 patient. This individualized treatment planning and controlled heat exposure allows adaptive, flexible and safe HT treatments in palliatively treated animal patients.

Reasons for living, meaning in life, and suicide ideation: investigating the roles of key positive psychological factors in reducing suicide risk in community-residing older adults

OBJECTIVES

To investigate the roles of reasons for living (RFL) and meaning in life (MIL) in potentially promoting mental health and well-being and protecting against suicide ideation among community-residing older adults and to investigate the psychometric properties of the Reasons for Living Scale-Older Adult version (RFL-OA).

METHOD

Of 173 older adults initially recruited into a longitudinal study on late-life suicide ideation, 109 completed the RFL-OA and measures of cognitive and physical functioning and positive and negative psychological factors at a two-year follow-up assessment. We tested a model in which RFL and MIL protect against suicide ideation, controlling for demographic and clinical factors. We also assessed the psychometric properties of the RFL-OA in community-residing older adults, investigating its internal consistency and its convergent (MIL, perceived social support, and life satisfaction), divergent (loneliness, depressive symptom severity, and suicide ideation), and discriminant validity (cognitive and physical functioning).

RESULTS

RFL-OA scores explained significant variance in suicide ideation, controlling for age, sex, depressive symptom severity, and loneliness. MIL explained significant unique variance in suicide ideation, controlling for these factors and RFL, and MIL significantly mediated the association between RFL and suicide ideation. Psychometric analyses indicated strong internal consistency (α = .94), convergent, divergent, and discriminant validity for the RFL-OA relative to positive and negative psychological factors and cognitive and physical functioning.

CONCLUSION

These findings add to a growing body of literature suggesting merit in investigating positive psychological factors together with negative factors when assessing suicide risk and planning psychological services for older adults.

The wish to die among palliative home care clients in Ontario, Canada: A cross-sectional study

Background

In the pursuit to provide the highest quality of person centered palliative care, client preferences, needs, and wishes surrounding end of life should be used to inform the plan of care. During a clinical assessment for care services, clients may voluntarily express a ‘wish to die’ either directly to the clinician or it may be indirectly reported second-hand to the clinician through an informal caregiver or family member. This is the first study using data gathered from the interRAI Palliative Care Assessment instrument (interRAI PC) to examine socio-demographic, clinical, and psycho-social factors of palliative home care clients with the voluntary expression of a ‘wish to die now’. Factors associated with the risk for depression within this group were also identified. Awareness and understanding of clients who express the ‘wish to die’ is needed to better tailor a person-centered approach to end-of-life care.

Methods

This cross-sectional study included assessment records gathered from 4,840 palliative home care clients collected as part of pilot implementation of the interRAI PC assessment instrument in Ontario, Canada from 2006 through 2011.

Results

During the clinical assessment, 308 palliative home care clients (6.7 %) had voluntarily expressed a ‘wish to die now’. Independent factors emerging from multivariate logistic regression analyses predicting the expression of a ‘wish to die’ included not being married/widowed, a shorter estimated prognosis, depressive symptoms, functional impairment, too much sleep (excessive amount), feeling completion regarding financial/legal matters, and struggling with the meaning of life. Among persons who expressed a ‘wish to die now’, those who exhibited depressive symptoms (23.8 %, n = 64) were also more likely to exhibit cognitive impairment, have decline in cognition in the last 90 days, exhibit weight loss, have informal caregivers exhibiting distress, ‘not have a consistent positive outlook on life’ and report ‘struggling with the meaning of life’.

Conclusion

When clients voluntary express a wish to die clinicians should take notice and initiate follow-up to better understand the context of this meaning for the individual. Clients who expressed a ‘wish to die’ did not all experience pain, depression, and psychological distress suggesting an individualized approach to care management be taken.

Risk and protective factors associated with intentional self-harm among older community-residing home care clients in Ontario, Canada

OBJECTIVE

We aim to concurrently examine risk and protective factors associated with intentional self-harm among community-residing older adults receiving home care services in Ontario, Canada.

METHODS

Administrative health data from the home care sector were linked to hospital administrative data to carry out the analyses. Home care data are collected in Ontario using the Resident Assessment Instrument-Home Care (RAI-HC), an assessment tool that identifies strengths, preferences and needs of long-stay home care clients. The sample included Ontario home care clients aged 60 years or older assessed with the RAI-HC between 2007 and 2010 (N = 222,149). Multivariable analyses were performed using SAS.

RESULTS

Hospital records of intentional self-harm (ISH) were present in 9.3 cases per 1000 home care clients. Risks of ISH included younger age (60-74 years; OR = 3.14, CI: 2.75-3.59), psychiatric diagnosis (OR = 2.29, CI: 2.06-2.54), alcohol use and dependence (OR = 1.69, CI: 1.34-2.14), psychotropic medication (OR = 1.94, CI: 1.75-2.15) and depressive symptoms (OR = 1.58, CI: 1.40-1.78). Protective effects were found for marital status and positive social relationships, yet these effects were more pronounced for men. Cognitive performance measures showed the odds of ISH 1.86 times higher for older adults with moderate to severe cognitive impairment.

CONCLUSIONS

This study based on provincial data points to tangible areas for preventative assessment by frontline home care professionals. Of interest were the risk and protective factors that differed by sex. As demand for home care in Canada is expected to increase, these findings may inform home care professionals' appraisal and approach to suicide prevention among community-residing older adults.

A longitudinal examination of rural status and suicide risk

There is limited research on suicide risk in Canadian home care. Older adults have the highest rates of death by suicide worldwide. This article examines characteristics of rural and urban home care recipients with a hospital or emergency department visit for suicide attempts in Ontario, Canada. Factors that increase or decrease risk for emergent care are identified. This research builds on a growing need for health leadership to ensure that home care providers have appropriate training and resources to assess and respond to potential risk of suicide among frail elders.

Predictors of frequent emergency department visits among rural older adults in Ontario using the Resident Assessment Instrument-Home Care

OBJECTIVE

To describe factors predicting frequent emergency department (ED) use among rural older adults receiving home care services in Ontario, Canada.

DESIGN

A cross-sectional examination of Ontario hospital administrative data linked to provincial home care data compares frequent ED users (i.e. >4 visits/year) with regular users (i.e. 1-3 visits/year) and no ED use over a 1-year period. Multiple logistic regression analysis was performed using independent variables from home care health assessments.

MAIN OUTCOME MEASURES

Predictors of frequent ED use among rural older adults receiving home care services using adjusted odds ratios (ORs) and 95% confidence intervals (CI).

RESULTS

Ontario's rural home care clients visited the ED an average of 4.9 times (SD = 11.9) over a year. Frequent ED users were observed in 170 cases per 1000 home care clients. Congestive heart failure was the most frequently cited reason for frequent ED use; however, it was not a main driver in the adjusted model. Frequent ED use was predicted by younger age (i.e. 60-74 years) (OR = 1.9; 95% CI, 1.7-2.2), a recent ED visit in the last 3 months (OR = 1.5; 95% CI, 1.4-1.7), regularly taking >9 medications (OR = 1.5; 95% CI, 1.3-1.6), and poor self-rated health (OR = 1.4; 95% CI, 1.2-1.5).

CONCLUSION

Despite popular assumptions, the main drivers for frequent ED use among rural older adults in Ontario included a mix of sociodemographic and clinical characteristics, rather than disease diagnoses.

Sexuality in later life: examining beliefs and perceptions of undergraduate students

Understanding students' beliefs and perceptions of sex/sexuality in later life can reduce and prevent ageist myths and stereotypes. The objective of this study was to gauge undergraduate students' knowledge of several myths, stereotypes, and facts regarding sex/sexuality in later life, including lesbian, gay, bisexual, and transgendered (LGBT) older adults. More than 85% of students held a positive view of sex/sexuality in later life with 65% believing that they would engage in sexual activity past age 80 (N=125). Correct responses to true/false questions were higher for those with a positive perspective on aging, and recognizing that sexual behavior does not cease to be important with aging was the strongest predictor of holding a positive view on sexuality in later life. No significant differences were observed from responses regarding LGBT older adults or constraints to sexuality in long term care facilities. The positive perceptions among students in the current study suggest an increased acceptance of sexuality and diversity that should be maintained in university curricula.

Children and adults exposed to electromagnetic fields at the ICNIRP reference levels: theoretical assessment of the induced peak temperature increase

To avoid potentially adverse health effects of electromagnetic fields (EMF), the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has defined EMF reference levels. Restrictions on induced whole-body-averaged specific absorption rate (SAR(wb)) are provided to keep the whole-body temperature increase (T(body, incr)) under 1 °C during 30 min. Additional restrictions on the peak 10 g spatial-averaged SAR (SAR(10g)) are provided to prevent excessive localized tissue heating. The objective of this study is to assess the localized peak temperature increase (T(incr, max)) in children upon exposure at the reference levels. Finite-difference time-domain modeling was used to calculate T(incr, max) in six children and two adults exposed to orthogonal plane-wave configurations. We performed a sensitivity study and Monte Carlo analysis to assess the uncertainty of the results. Considering the uncertainties in the model parameters, we found that a peak temperature increase as high as 1 °C can occur for worst-case scenarios at the ICNIRP reference levels. Since the guidelines are deduced from temperature increase, we used T(incr, max) as being a better metric to prevent excessive localized tissue heating instead of localized peak SAR. However, we note that the exposure time should also be considered in future guidelines. Hence, we advise defining limits on T(incr, max) for specified durations of exposure.

Knowing me-knowing you: Reported personality and trait discrepancies as predictors of marital idealization between long-wed spouses

In previous research, marital idealization has emerged as a significant predictor of adaptation to widowhood, the psychological well-being of spouses of persons with dementia, and the physical health of older married adults over time. Despite the adaptive value of marital idealization, conceptual confusion regarding this phenomenon persists. To this end, the present study examines the degree to which marital idealization is predicted by personality traits relative to partner perceptions of their spouse's personality, and discrepancies between self- vs. spousal reports for both husbands and wives. Multilevel models were computed on the basis of responses from 125 couples married an average of 34 years. Marital idealization by husbands was predicted by his personality (i.e., lower neuroticism, openness to experience, agreeableness, and higher conscientiousness). In contrast, marital idealization by wives was predicted by trait discrepancies (i.e., being seen, and seeing one's spouse, more positively than she or he sees him- or herself). Conscientiousness emerged as the trait for which between-sex differences were most pronounced, whereas both conscientiousness and agreeableness were the traits most broadly associated with marital idealization by both spouses (intracouple trait averages and discrepancies between spousal reports). These results are discussed in relation to gender socialization and between-sex differences.

Enhanced measurement sensitivity of hopeless ideation among older adults at risk of self-harm: Reliability and validity of Likert-type responses to the Beck Hopelessness Scale

OBJECTIVE

Responses to the Beck Hopelessness Scale (BHS) have been identified as a significant predictor of suicide-related ideation and self-harm, of note, to a greater degree than severity of depressive symptoms. The BHS is the most widely used instrument to assess this construct, yet concern has been expressed about the traditional true/false response format of this instrument. For this study, we obtained responses from older adults to a revised four-point Likert-type BHS response format.

METHOD

A national sample of 117 older Canadians at risk of self-harm was recruited from multiple sources for this study over a one-year period. Most participants were women (65%) with an average age of 68.47 years (SD = 9.02, range 50-92).

RESULTS

Exploratory factor analysis suggests the existence of two factors labeled Powerlessness/Disappointment and Negative Future Expectancies. Concurrent validity of this two-factor model of BHS responses is provided vis-a-vis suicide-related ideation subsequent to statistical control for socio-demographic factors, physical health, and depressive symptomatology. Of note, the relative contribution to the measurement of BHS factors is proportionately equal and greater than all other independent variables.

CONCLUSION

We contend that this revised BHS response format may be appropriate for use in clinical and research applications though replication with other samples and populations is warranted.

The clinical feasibility of deep hyperthermia treatment in the head and neck: new challenges for positioning and temperature measurement

To apply high-quality hyperthermia treatment to tumours at deep locations in the head and neck (H&N), we have designed and built a site-specific phased-array applicator. Earlier, we demonstrated its features in parameter studies, validated those by phantom measurements and clinically introduced the system. In this paper we will critically review our first clinical experiences and demonstrate the pivotal role of hyperthermia treatment planning (HTP). Three representative patient cases (thyroid, oropharynx and nasal cavity) are selected and discussed. Treatment planning, the treatment, interstitially measured temperatures and their interrelation are analysed from a physics point of view. Treatments lasting 1 h were feasible and well tolerated and no acute treatment-related toxicity has been observed. Maximum temperatures measured are in the range of those obtained during deep hyperthermia treatments in the pelvic region but mean temperatures are still to be improved. Further, we found that simulated power absorption correlated well with measured temperatures illustrating the validity of our treatment approach of using energy profile optimizations to arrive at higher temperatures. This is the first data proving that focussed heating of tumours in the H&N is feasible. Further, HTP proved a valuable tool in treatment optimization. Items to improve are (1) the transfer of HTP settings into the clinic and (2) the registration of the thermal dose, i.e. dosimetry.

Impulsivity and hopelessness as predictors of suicide-related ideation among older adults

OBJECTIVE

Research has demonstrated that impulsivity is strongly associated with suicide-related ideation and behaviour among young adults. However, to date, the potential importance of impulsivity as a predictor of suicide-related ideation in later life has yet to be determined. Our study examined impulsivity, hopelessness, depressive symptomatology, and sociodemographic factors vis-à-vis suicide-related ideation among older adults at risk of self-harm.

METHOD

A sample (n = 117) of older adults was recruited from multiple sources for this study over a 1-year period. Suicide-related ideation was measured with the Geriatric Suicide Ideation Scale, a multidimensional measure of suicide-related ideation developed for use with older adults.

RESULTS

Canonical correlation identified 2 pairings of linear composites in which impulsivity emerged along both as significantly associated with facets of suicide-related ideation. Of note, the greater proportion of variance in impulsivity was subsumed along the second set of vectors with somatic depressive symptoms.

CONCLUSION

Our findings suggest that the impulse to self-harm may be even more pronounced among older adults less likely to present as typically depressed. It is further suggested that impulsivity is more broadly associated with suicide-related ideation than hopelessness, and that screening for impulsivity as well as hopelessness may increase clinicians' ability to identify older adults at greatest risk of self-harm.

Measurement, simulation and uncertainty assessment of implant heating during MRI

The heating of tissues around implants during MRI can pose severe health risks, and careful evaluation is required for leads to be labeled as MR conditionally safe. A recent interlaboratory comparison study has shown that different groups can produce widely varying results (sometimes with more than a factor of 5 difference) when performing measurements according to current guidelines. To determine the related difficulties and to derive optimized procedures, two different generic lead structures have been investigated in this study by using state-of-the-art temperature and dosimetric probes, as well as simulations for which detailed uncertainty budgets have been determined. The agreement between simulations and measurements is well within the combined uncertainty. The study revealed that the uncertainty can be kept below 17% if appropriate instrumentation and procedures are applied. Optimized experimental assessment techniques can be derived from the findings presented herein.

Recurrent depressive symptomatology and physical health: a 10-year study of informal caregivers of persons with dementia

OBJECTIVE

To examine the degree to which recurrent depressive symptomatology predicts the decline in the health status of a randomly derived national sample of caregivers of persons with dementia.

METHOD

Individuals with dementia and their caregivers were recruited from each Canadian province as part of a national epidemiologic study of dementia prevalence and the health and welfare of care providers. Both patients and caregivers were assessed at 3 points over a 10-year period. Cohabiting family members who shared the same residence as care recipients were selected for the current study (n = 96 pairs). We computed a repeated measures analysis of variance to compare the health of caregivers who were consistently asymptomatic for depression, of those symptomatic at 1 of 3 points of measurement, and of those symptomatic at 2 of 3 points.

RESULTS

As hypothesized, caregivers presenting with elevated depressive symptomatology at multiple points of measurement reported poorer and worsening physical health over time.

CONCLUSIONS

The results of this study support the assertion that depressive symptomatology significantly predicts the decline in health status of caregivers of persons with dementia. Concerted effort to treat depression in this population is warranted to forestall this trajectory of decline and premature patient institutionalization.

Novel conformal technique to reduce staircasing artifacts at material boundaries for FDTD modeling of the bioheat equation

The modeling of thermal effects, often based on the Pennes Bioheat Equation, is becoming increasingly popular. The FDTD technique commonly used in this context suffers considerably from staircasing errors at boundaries. A new conformal technique is proposed that can easily be integrated into existing implementations without requiring a special update scheme. It scales fluxes at interfaces with factors derived from the local surface normal. The new scheme is validated using an analytical solution, and an error analysis is performed to understand its behavior. The new scheme behaves considerably better than the standard scheme. Furthermore, in contrast to the standard scheme, it is possible to obtain with it more accurate solutions by increasing the grid resolution.

Prevalence of fractures among the Thalassemia syndromes in North America

Historically, fractures are cited as a frequent problem in patients with Thalassemia prior to optimization of transfusion and chelation regimens. The aim of this study was to determine the prevalence of fractures in a contemporary sample of North American patients with Thalassemia. The North American Thalassemia Clinical Research Network (TCRN) database registry was used to gather historical data on 702 patients with common alpha and beta-Thalassemia diagnoses including Thalassemia Major (TM), Intermedia (TI), E/Beta, homozygous alpha Thalassemia (AT), Hemoglobin H disease (HbH) and HbH with Constant Spring (HbH/CS), who consented to a medical record chart review. Bone mineral density (BMD) measurements by DXA were available for review in a subgroup of patients (n = 312). The overall fracture prevalence among all Thalassemia syndromes was 12.1%, equally distributed between females (11.5%) and males (12.7%). Fractures occurred more frequently in TM (16.6%) and TI (12.2%) compared to E/Beta (7.4%) and alpha (2.3%). Prevalence increased with age (2.5% ages 0-10 years, 7.4% ages 11-19 years, 23.2% ages >20 years) and with use of sex hormone replacement therapy (SHRT) (P < 0.01). On average, BMD Z and T scores were 0.85 SD lower among patients with a history of fractures (mean Z/T score -2.78 vs. -1.93, 95% CI for the difference -0.49 to -1.22 SD, P = 0.02). Presence of other endocrinopathies (i.e. hypothyroidism, hypoparathyroidism and diabetes mellitus), anthropometric parameters, heart disease or hepatitis C were not significant independent predictors of fractures. These data indicate that fractures remain a frequent complication among the aging patients with both TM and TI beta-Thalassemia. However, the fracture prevalence has improved compared to published reports from the 1960s to 1970s. In addition, children with Thalassemia appear to have low fracture rates compared to the general population.

D. Harvey Philip. Schizophrenia in Late Life: Aging Effects on Symptoms and Course of Illness. Washington, DC: American Psychological Association, 2005

Schizophrenia in Late Life apporte une contribution précieuse à la documentation et à la recherche sur cette maladie débilitante. Le quatrième livre du docteur Harvey, Schizophrenia in Late Life, couvre plusieurs des aspects importants de la maladie et propose des discussions approfondies sur les changements fonctionnels et cognitifs reliés à l'âge. Étant donné qu'un nombre appréciable de personnes souffrant de schizophrénie arrive à un âge avancé pour la première fois dans l'histoire de l'humanité, ce livre apportera une contribution importante pour les cliniciens et les chercheurs.

Cessation of rapid late endosomal tubulovesicular trafficking in Niemann-Pick type C1 disease

Niemann-Pick type C1 (NPC1) disease results from a defect in the NPC1 protein and is characterized by a pathological accumulation of cholesterol and glycolipids in endocytic organelles. We followed the biosynthesis and trafficking of NPC1 with the use of a functional green fluorescent protein-fused NPC1. Newly synthesized NPC1 is exported from the endoplasmic reticulum and requires transit through the Golgi before it is targeted to late endosomes. NPC1-containing late endosomes then move by a dynamic process involving tubulation and fission, followed by rapid retrograde and anterograde migration along microtubules. Cell fusion studies with normal and mutant NPC1 cells show that exchange of contents between late endosomes and lysosomes depends upon ongoing tubulovesicular late endocytic trafficking. In turn, rapid endosomal tubular movement requires an intact NPC1 sterol-sensing domain and is retarded by an elevated endosomal cholesterol content. We conclude that the neuropathology and cellular lysosomal lipid accumulation in NPC1 disease results, at least in part, from striking defects in late endosomal tubulovesicular trafficking.

Fluorescence derivatisation of urinary corticosteroids for high-performance liquid chromatographic analysis

Corticosteroids containing a C21 primary hydroxyl group were derivatised with 9-anthroyl cyanide. The reagent was prepared as a solution in acetonitrile, containing 0.1% triethylamine, at a concentration of 2 mg/ml. Approximately 1 microg of corticosteroid was reacted with 100 microl of this reagent, at 45 degrees C for 2 h. The fluorescent derivatives were separated by HPLC on a silica column, 250x4.6 mm I.D., by stepwise elution, with a mobile phase of 2-propanol-hexane (2:98) for 20 min, followed by 2-propanol-hexane (7:93) from 20 to 40 min. The fluorescence detector was set to 370-nm excitation and 470-nm emission. The relatively low temperature for derivatisation avoided reaction with secondary hydroxyl groups and also prevented thermal degradation of the corticosteroids.

Failure of current guidelines for cholesterol screening in urban African-American adolescents

OBJECTIVE

The National Cholesterol Education Program (NCEP) and the American Academy of Pediatrics recommend selective screening to detect children and adolescents with hypercholesterolemia. We compared the effectiveness of these guidelines with other potential screening strategies in urban African-American adolescents.

SUBJECTS AND METHODS

Two hundred sixty African-American adolescents and young adults (192 females and 68 males; age range, 12 to 20 years) who were free from illnesses or medications that disrupt lipid metabolism were included in the study. Participants completed a questionnaire regarding their smoking habits, blood pressure, contraceptive pill use, and family history of early heart disease and high cholesterol and had their blood lipids, lipoproteins, and apolipoproteins measured (152 fasting and 108 nonfasting).

RESULTS

Nineteen percent of participants reported family histories of hypercholesterolemia; 26% reported family histories of premature heart disease; and 8% had family histories of both hypercholesterolemia and premature heart disease. Therefore, 37% of these participants would have been targeted for cholesterol screening, compared with the 25% predicted by the NCEP. Less than 50% of the participants with low-density lipoprotein cholesterol (LDL-C) levels greater than 110 or 130 mg/dL would have been detected by selective screening. Total cholesterol was superior as a screening test to apolipoprotein B in predicting LDL-C levels greater than 110 mg/dL (sensitivity, 92% vs 59%). However, total cholesterol minus high-density lipoprotein cholesterol showed better positive predictive value (100%) at LDL-C levels greater than 110 mg/dL than total cholesterol in the fasting (80%) and total groups (90%).

CONCLUSIONS

In this population, selective screening with total cholesterol, as recommended by the NCEP, has such poor sensitivity and positive predictive value that other options may be superior. As an alternative, we recommend the measurement of high-density lipoprotein cholesterol together with total cholesterol at the initial screening step in adolescents and universal screening for those older than 16 years to capture a greater proportion of young adults with increased LDL-C. Furthermore, we recommend using the less stringent treatment guidelines established by the Adult Treatment Panel II for premenopausal women and men younger than 35 years for older adolescents and young adults.

The differences among Jewish communities--maternal and paternal contributions

The haplotypes of Y chromosome (paternally inherited) and mtDNA (maternally inherited) were analyzed in representatives of six Jewish communities (Ashkenazic, North African, Near Eastern, Yemenite, Minor Asian/Balkanian, and Ethiopian). For both elements, the Ethiopian community has a mixture of typically African and typically Caucasian haplotypes and is significantly different from all others. The other communities, whose haplotypes are mostly Caucasian, are more closely related; significant differences that were found among some of them possibly indicate the effects of admixture with neighboring communities of non-Jews. The different contribution of the Y chromosome and mtDNA haplotypes to the significant differences among the communities can be explained by unequal involvement of males and females in the different admixtures. In all communities, except the Ethiopians, the level of diversity (h) for Y chromosome haplotypes is higher than that for mtDNA haplotypes, suggesting that in each community the people who become parents include more males than females. An opposite proportion (more females than males) is found among the Ethiopians.

Mitochondrial DNA affinity of several Jewish communities

The mitochondrial DNA (mtDNA) of 332 individuals from Israel, including 270 Jews (originating from 7 communities) and 62 Arabs, was analyzed. Each mtDNA haplotype was determined by the fragment patterns of restriction enzymes HpaI, BamHI, HaeII, MspI (HpaII), and AvaII. The variability of the total sample and of each community was high. Of 40 different haplotypes, 20 were found more than once. Most haplotypes are typical of Caucasians, but African types were found among Ethiopian Jews and to a lesser extent among Arabs. The communities differed in their haplotypes: Chi-square tests among six communities showed significant differences for most pairwise comparisons and nonsignificant differences involving mainly the Moroccan Jews. In a genetic distance analysis only the Ethiopian Jews appeared to be distinguished from the other communities. According to a GST analysis, approximately 30% of the variation among the mtDNA restriction maps is attributable to differences between communities.

pp60c-src in human melanocytes and melanoma cells exhibits elevated specific activity and reduced tyrosine 530 phosphorylation compared to human fibroblast pp60c-src

Elevated levels of pp60c-src tyrosine kinase activity have been implicated in both tumorigenesis and cell differentiation. We have found a 2- to 4-fold elevation in pp60c-src specific activity in certain human melanoma cell lines compared to human foreskin fibroblasts. This activation of pp60c-src did not appear to be related to melanoma tumor progression, because when normal human epidermal melanocytes were examined, it was found that they contained pp60c-src having a 7-fold elevation in specific activity compared to pp60c-src from human fibroblasts. It was determined that pp60c-src from melanocytes was not the neuronal form, pp60c-src+. Melanocyte pp60c-src exhibited a reduced level of phosphorylation on its carboxyl-terminal regulatory site, tyrosine 530, which might be responsible for its elevated specific activity. These results suggest that, in melanocytes, regulation of tyrosine 530 phosphorylation-dephosphorylation favors activation of pp60c-src. This activation may be involved in the growth, differentiation, or function of human melanocytes.

Origins of H-2 polymorphism in the house mouse. II. Characterization of a model population and evidence for heterozygous advantage

Comparison of the rate of synonymous and nonsynonymous nucleotide substitutions suggests that certain regions of the functional H-2 genes, which are part of the mouse major histocompatibility complex (Mhc), are under strong positive selection pressure. Thus far, however, little evidence has been provided for the existence of such pressure in natural mouse populations. We have, therefore, initiated experiments designed to test the hypothesis of positive selection acting on H-2 loci. The experiments are being carried out on two natural mouse populations in Jerusalem, Israel. One population occupies a space of about 100 m2 in a chicken coop, the other lives in a nearby field in which "mouse stations" providing food and shelter have been set up. Extensive typing of these two populations revealed the presence of only four H-2 haplotypes. Mice in the two populations breed continually all year around, yet population size varies seasonally, with population maxima in winter and minima in summer. The population in the chicken coop contains a relatively stable nucleus which may be organized in demes with an excess of females over males and limited territorial mobility. The rest of the mice stay in the population for a short time only and then either die or emigrate. The field population is smaller and more loosely organized than the chicken-coop population, with demes probably forming only during population maxima. For the rest of the time breeding in this population is probably panmictic. At a population minimum in the summer of 1984, H-2 homozygotes happened to predominate over heterozygotes. This situation, however, lasted for a short time only and thereafter there was a continuous, statistically highly significant increase in the proportion of H-2 heterozygotes of one or two types. The increase occurred in both populations but was more apparent in the chicken-coop population. This observation provides the first experimental evidence that heterozygous advantage might be one of the mechanisms maintaining high H-2 polymorphism in natural populations of the house mouse.

Limits of the distal inversion in the t complex of the house mouse: evidence from linkage disequilibria

The suppression of crossing-over and the consequent linkage disequilibrium of genetic markers within the t complex of the house mouse is caused by two large and two short inversions. The inversions encompass a region that is some 15 centiMorgans (cM) long in the homologous wild-type chromosome. The limits of the proximal inversions are reasonably well-defined, those of the distal inversions much less so. We have recently obtained seven new DNA markers (D17Tu) which in wild-type chromosomes map into the region presumably involved in the distal inversions of the t chromosomes. To find out whether the corresponding loci do indeed reside within the inversions, we have determined their variability among 26 complete and 12 partial t haplotypes. In addition, we also tested the same collection of t haplotypes for their variability at five D17Leh, Hba-ps4, Pim-1, and Crya-1 loci. The results suggest that the distal end of the most distal inversion lies between the loci D17Leh467 and D17Tu26. The proximal end of the large distal inversion was mapped to the region between the D17Tu43 and Hba-ps4 loci, but this assignment is rather ambiguous. The loci Pim-1, Crya-1, and the H-2 complex, which have been mapped between the Hba-ps4 and Grr within the large distal inversion, behave as if they recombine from time to time with their wild-type homologs.

Phospholipid changes in the bones of the hypophosphatemic mouse

The mineral and lipid composition of the bones of 35 day old hypophosphatemic (Hyp/Y) and control (+/Y) mice were compared in order to test the hypothesis that phosphate status has an effect on the complexed acidic phospholipid content of developing bones. The Hyp/Y bones were found to be rachitic and osteomalacic, having significantly reduced mineral content. That mineral was shown by X-ray diffraction to consist of larger/more perfect crystals than that in +/Y animals, indicating either a preference for crystal growth rather than new mineral deposition, or an increased mineral turnover. The increased crystal perfection was confirmed by chemical analyses which showed an increased calcium to phosphorus ratio in the Hyp/Y bones. The bones of Hyp/Y animals had significantly reduced complexed acidic phospholipid contents relative to those of control animals. Since these complexes are believed to play a role in vitro and in vivo mineral deposition, it is suggested that the deficiency of these complexes contributes to the mineralization defect. The magnitude of the complexed acidic phospholipid deficiency in the Hyp/Y animals indicates the importance of phosphate for the formation of these lipids. Although the proportion of phosphatidylserine and phosphatidylinositol and lysophospholipids tended to be reduced in the Hyp/Y bones, the absence of other statistically significant phospholipid abnormalities in the bones and brains of these animals suggests that the lipid defect is not systemic, but is associated with a decrease in phosphate at the site of bone formation.

A 180,000 molecular weight glycoprotein substrate of the insulin receptor tyrosine kinase is present in human placenta and in rat liver, muscle, heart and brain plasma membrane preparations

Cell signalling for insulin may include insulin receptor tyrosine kinase catalysing the phosphorylation of one or more cell proteins. Since temporally the insulin receptor will encounter plasma membrane proteins first, we have studied the in vitro phosphorylation of purified plasma membrane preparations. Two proteins were immunoprecipitated with anti-phosphotyrosine antibody from rat liver, muscle, heart and brain membranes and from human placenta membranes: the insulin receptor (detected as a phosphorylated-beta-subunit) and a 180,000 molecular weight protein (pp180). pp180 is a monomeric glycoprotein that in the absence of dithiothreitol migrated in denaturing gels like a 150,000 molecular weight protein. pp180 was a substrate for the insulin receptor: (i) receptor and pp180 phosphorylation followed a similar insulin dose-response, although fold-stimulation of autophosphorylation was greater; and (ii) removal of insulin receptors with monoclonal antibodies prevented subsequent pp180 phosphorylation. Insulin-activated receptors increased the extent, but not the rate, of pp180 phosphorylation; the increased phosphate was incorporated into tyrosine and appeared to do so in three or four of pp180's 12 tryptic phosphopeptides. Some data suggest that pp180 is the same protein in each of the tested tissues. The occurrence of pp180, an insulin receptor substrate, in plasma membranes of several insulin responsive tissues suggests that it has a role in insulin signalling.

Thin-layer chromatography can resolve phosphotyrosine, phosphoserine, and phosphothreonine in a protein hydrolyzate

A solution of propionic acid, 1 M ammonium hydroxide, and isopropyl alcohol (45/17.5/17.5, v/v) was the ascending solvent in the separation of phosphotyrosine, phosphothreonine, and phosphoserine by thin-layer chromatography. The immobile phase was cellulose. The relative migrations were 0.44, 0.38, and 0.2, respectively. A previously described thin-layer system consisting of isobutyric acid and 0.5 M ammonium hydroxide (50/30, v/v) gave very similar relative migrations. To determine the usefulness of thin-layer chromatography in phosphoamino acid analysis, the propionic acid/ammonium hydroxide/isopropyl alcohol solution was used to characterize phosphorylated residues in a plasma membrane protein which is a substrate for the insulin receptor kinase, in insulin receptor phosphorylated histone H2B, and in an in vivo phosphorylated 90000-Da protein from IM9 cells. 32P-labeled proteins were separated by dodecyl sulfate-gel electrophoresis, digested with trypsin, and then hydrolyzed with 6 N HCl, 2 h, 110 degrees C. Following thin-layer chromatography of the hydrolyzates and autoradiography, phosphotyrosine was detected in insulin receptor substrates, and phosphoserine and phosphothreonine were found in the in vivo-phosphorylated protein. This study supports previous reports about the practicality of thin-layer chromatography in phosphoamino acid analysis and it demonstrates that a propionic acid, ammonium hydroxide, isoprophyl alcohol solution may be a useful ascending solvent mixture for this purpose.

t-Specific DNA polymorphisms among wild mice from Israel and Spain

Lehrach and his coworkers have isolated a series of DNA probes that specifically hybridize with different regions of mouse chromosome 17 within the t complex. The probes display restriction fragment length polymorphisms, RFLPs, which are specific for the t haplotypes in all laboratory mouse strains tested thus far. Some of these probes have been used to test wild mice populations for these t-associated DNA forms. It is demonstrated that populations from Germany, Switzerland, Italy, Greece, Yugoslavia, Australia, Costa Rica, and Venezuela contain chromosomes in which all the tested DNA loci display the t-specific polymorphisms. The frequency of mice carrying these chromosomes is as high as 31%. Wild mice from Israel and Spain, on the other hand, carry chromosomes displaying t-specific DNA forms only at one or two of the probed loci, while the other loci carry the wild-type (+) forms. These chromosomes thus resemble the partial t haplotypes known from the study of laboratory mice. One possible interpretation of these findings is that these DNA polymorphisms contributed to the assembly of the complete t haplotypes and that these haplotypes may have originated in the Middle East.

Polymorphism of unique noncoding DNA sequences in wild and laboratory mice

Two DNA probes, D17Tu1 and D17Tu2, were isolated from a genomic DNA library containing only two mouse chromosomes, one of which is chromosome 17, carrying the major histocompatibility complex (H-2), as well as the t complex genes. The D17Tu1 probe was mapped to the centromeric region of chromosome 17 and the D17Tu2 probe to the S region of the H-2 complex. Neither of the two probes appeared to detect any genes, but both contained unique, nonrepetitive sequences. Typing of DNA obtained from a large panel of mice revealed the presence of four D17Tu1 patterns in inbred mouse strains, one very common, one less common, and two present in one strain each. The two common patterns could not be detected in appreciable frequencies in the European wild mice tested (one of the two patterns was, however, found in Australian wild mice). Conversely, the patterns found frequently in European wild mice are absent in the laboratory mice. We therefore conclude that wild mice from the sampled regions of Europe could not have provided the ancestral stocks from which inbred strains were derived. Only one D17Tu1 pattern was found in all the populations of Mus musculus tested, while eight patterns were found in Mus domesticus, with virtually all the populations being polymorphic. We suggest that this difference reflects different modes in which the two species colonized Europe. The distribution of the D17Tu2 patterns in inbred strains correlates with the distribution of H-2 haplotypes.

A plasmamembrane redox system and proton transport in isolated mesophyll cells

Potassium ferricyanide (K(3)Fe[CN](6)) was added to aerated and stirred nonbuffered suspensions of mechanically isolated photosynthetically competent Asparagus sprengeri Regel mesophyll cells. Rates of Fe(CN)(6) (3-) reduction and H(+) efflux were measured with or without illumination. On the addition of 1 millimolar Fe(CN)(6) (3-) to nonilluminated cell suspensions acidification of the medium indicated an H(+) efflux of 1.54 nanomoles H(+)/10(6) cells per minute. Simultaneous Fe(CN)(6) (3-) reduction occurred at a rate of 1.55 nanomoles Fe(CN)(6) (3-)/10(6) cells per minute. Illumination stimulated these rates 14 to 17 times and corresponding values were 26.1 nanomoles H(+)/10(6) cells per minute and 22.9 nanomoles Fe(CN)(6) (3-)/10(6) cells per minute. These two processes appeared to be tightly coupled and were rapidly inhibited when illuminated suspensions were transferred to darkness or treated with 1 micromolar 3-(3,4-dichlorophenyl)-1,1 dimethylurea. Addition of 0.1 millimolar diethylstilbestrol eliminated ATP dependent H(+) efflux in illuminated or nonilluminated cells but had no influence on Fe(CN)(6) (3-) dependent H(+) efflux. Recent reports indicate that a transmembrane redox system spans the plasma membrane of root cells and is coupled to the efflux of H(+). The present report extends these observations to photosynthetically competent mesophyll cells. The results indicate a transport process independent of ATP driven H(+) efflux which operates with a H(+)/e(-) stoichiometry of one.

Low H-2 polymorphism in some Israeli wild mouse populations

Two populations of the wild house mouse, Mus domesticus, found living close to each other (one inhabited a chicken coop and the other an open field at the Educational Farm of the Hebrew University of Jerusalem, East Talpiot, Jerusalem) were studied for their H-2 polymorphism. These two populations were selected because they are well characterized in terms of their ecological parameters; they have been under continuous surveillance for several years. Twenty-seven H-2 homozygous lines were produced by mating wild mice from these two populations with laboratory strains. The H-2w homozygotes were then characterized by serological typing with monoclonal and polyclonal antibodies specific for the known allomorphs controlled by the class I H-2K and H-2D loci or the class II H-2A and H-2E loci. They were also used as donors for immunizations and for the selection of antisera defining the H-2 haplotypes carried by these lines. Four new H-2 haplotypes could be identified: H-2w82 (Kw16 Dw82), H-2w83 (Kw83 Dw16), H-2w84 (Kw84 Dw84), and H-2w85 (Kw83 Dw84), the last haplotype being a recombinant derived from H-2w83 and H-2w84. Antisera defining the new haplotypes were then used for a study of the wild populations. This study revealed that the populations contain only the four identified H-2 haplotypes, having three alleles at the H-2K locus (Kw16, Kw83, Kw84) and three alleles at the H-2D locus (Dw16, Dw82, and Dw84). The alleles occur in the populations with a frequency of 0.12-0.54. There were no significant differences in gene frequencies between the two populations, and the allele frequencies remained more or less stable. There was a significant excess of heterozygotes for at least some of the genes, compared with the frequency expected from Hardy-Weinberg equilibrium. The same antisera were also used to type other populations in the vicinity of Jerusalem. In one population, located 30 km west of Jerusalem, the mice failed to react with any of the reagents. In the other two populations, located 15 km west and 40 km northeast of Jerusalem, three of the four H-2 haplotypes found in East Talpiot were present at high frequencies. It appears, therefore, that only three main H-2 haplotypes and two or three minor ones are present in the area around Jerusalem. This study thus provides the first example of a large mainland population in which the H-2 polymorphism is comparable to that of many other non-H-2 loci.