Insight into the relationship between brain/behavioral speed and variability in patients with minimal hepatic encephalopathy.

OBJECTIVE: Intra-individual variability (IIV) of response reaction times (RTs) and psychomotor slowing were proposed as markers of brain dysfunction in patients with minimal hepatic encephalopathy (MHE), a subclinical disorder of the central nervous system frequently detectable in patients with liver cirrhosis. However, behavioral measures alone do not enable investigations into the neural correlates of these phenomena. The aim of this study was to investigate the electrophysiological correlates of psychomotor slowing and increased IIV of RTs in patients with MHE. METHODS: Event-related potentials (ERPs), evoked by a stimulus-response (S-R) conflict task, were recorded from a sample of patients with liver cirrhosis, with and without MHE, and a group of healthy controls. A recently presented Bayesian approach was used to estimate single-trial P300 parameters. RESULTS: Patients with MHE, with both psychomotor slowing and higher IIV of RTs, showed higher P300 latency jittering and lower single-trial P300 amplitude compared to healthy controls. In healthy controls, distribution analysis revealed that single-trial P300 latency increased and amplitude decreased as RTs became longer; however, in patients with MHE the linkage between P300 and RTs was weaker or even absent. CONCLUSIONS: These findings suggest that in patients with MHE, the loss of the relationship between P300 parameters and RTs is related to both higher IIV of RTs and psychomotor slowing. SIGNIFICANCE: This study highlights the utility of investigating the relationship between single-trial ERPs parameters along with RT distributions to explore brain functioning in normal or pathological conditions.

A novel method for the determination of the EEG individual alpha frequency.

The individual alpha frequency (IAF) is one of the most common tools used to study the variability of EEG rhythms among subjects. Several approaches have been proposed in the literature for IAF determination, including the popular peak frequency (PF) method, the extended band (EB) method, and the transition frequency (TF) method. However, literature techniques for IAF determination are over-reliant on the presence of peaks in the EEG spectrum and are based on qualitative criteria that require visual inspection of every individual EEG spectrum, a task that can be time consuming and difficult to reproduce. In this paper a novel channel reactivity based (CRB) method is proposed for IAF computation. The CRB method is based on quantitative indexes and criteria and relies on task-specific alpha reactivity patterns rather than on the presence of peaks in the EEG spectrum. Application of the technique to EEG signals recorded from 19 subjects during a cognitive task demonstrates the effectiveness of the CRB method and its capability to overcome the limits of PF, EB, and TF approaches.

Silencing or knocking out the Na(+)/Ca(2+) exchanger-3 (NCX3) impairs oligodendrocyte differentiation.

Changes in intracellular [Ca(2+)](i) levels have been shown to influence developmental processes that accompany the transition of human oligodendrocyte precursor cells (OPCs) into mature myelinating oligodendrocytes and are required for the initiation of the myelination and re-myelination processes. In the present study, we explored whether calcium signals mediated by the selective sodium calcium exchanger (NCX) family members NCX1, NCX2, and NCX3, play a role in oligodendrocyte maturation. Functional studies, as well as mRNA and protein expression analyses, revealed that NCX1 and NCX3, but not NCX2, were divergently modulated during OPC differentiation into oligodendrocyte phenotype. In fact, whereas NCX1 was downregulated, NCX3 was strongly upregulated during oligodendrocyte development. The importance of calcium signaling mediated by NCX3 during oligodendrocyte maturation was supported by several findings. Indeed, whereas knocking down the NCX3 isoform in OPCs prevented the upregulation of the myelin protein markers 2',3'-cyclic nucleotide-3'-phosphodiesterase (CNPase) and myelin basic protein (MBP), its overexpression induced an upregulation of CNPase and MBP. Furthermore, NCX3-knockout mice showed not only a reduced size of spinal cord but also marked hypo-myelination, as revealed by decrease in MBP expression and by an accompanying increase in OPC number. Collectively, our findings indicate that calcium signaling mediated by NCX3 has a crucial role in oligodendrocyte maturation and myelin formation.

Drinking during pregnancy: practices of Cambodian refugees in France and the United States.

This study is part of a larger exploratory study of 155 women of Cambodian national origin who were interviewed in the United States and France. This study reports on data related to frequency of alcohol usage, prevalence of drinking over the trimesters of pregnancy, beverage of choice, whether they spoke either English or French when leaving Cambodia, years of education, and current income. In this sample, Cambodian women residing in France drank more frequently, and drank different substances than those women residing in the United States. With respect to drinking during pregnancy, 37% of the women in France and 23% of the women residing in the United States drank in the first trimester. During the second and third trimesters, however, only 5% of the women in France, compared with 18% of women in the United States, continued drinking. It is suggested that different cultural practices in France and the United States account for differences in initial drinking practices. Three possible explanations were suggested to account for the fact that more Cambodian women residing in the United States, as compared with France, reported continued drinking over the course of their pregnancies: more limited health care access, differential selection policies for admittance, and lower overall socioeconomic status (SES). All French women, unlike American women, are covered by a comprehensive program of maternal and child health care. In addition, the Cambodian women residing in France were older, had more years of education, higher incomes, and a greater percentage spoke French before they left Cambodia. The results emphasize the relationship of socioeconomic factors to substance use and point toward a need for programs designed to educate Cambodian women with respect to the problems associated with drinking during pregnancy.

Depression and anxiety among Cambodian refugee women in France and the United States.

This study reports on Cambodian refugee data related to signs symptomatic of depression and anxiety, the tendency to worry or ruminate over past events (a culture-bound syndrome called "Khoucherang"), and differences that might be influenced by social system and cultural practice. A sample consisting of 155 women of Cambodian national origin were interviewed in their homes in the USA and France. Answers to the research questions were collected by a focused interview to elicit demographic information, and the Hopkins Symptom Checklist (HSCL) in the Cambodian language to elicit depression and anxiety scores. Women residing in France (87%) were significantly more likely to show signs symptomatic of depression than women residing in the USA (65%). Women in the study reported about three times as much depression as the average American woman. Large numbers of women residing in both countries were symptomatic of anxiety (82% on average). Both groups experienced extreme symptoms of the culture-bound syndrome, "Khoucherang," and appeared to be strongly influenced by the different social systems of the two countries.

Southeast Asians: Asian-Pacific Americans at risk for substance misuse.

Projections indicate that by the year 2000 over a million Cambodians, Laotians, and Vietnamese will be living in the United States. There is sparse information relative to the use of substances by these groups due to the absence of national prevalence data. The combined stressors that these refugee groups have faced puts them at high risk for substance misuse. Southeast Asians infrequently use substance misuse and mental health services, which has been perceived as a lack of need for services by these groups. In reality, there is a critical shortage of culturally-appropriate treatment and intervention programs as the prevalence of substance misuse increases in these populations.

Culture, stress and substance use in Cambodian refugee women.

Initial data were generated on the use of alcohol and other drugs by Cambodian refugee women and their families (N = 120) in two sites: Massachusetts and California. Information on frequency and situations surrounding use, and culturally specific use, was elicited. In those families where alcohol was perceived as a problem, the majority of problem drinkers were husbands. About 45% of the East Coast women, however, said they used alcohol for nervousness, stress, headaches, insomnia and pain. In addition, about 15% of the East Coast women reported that a family member used street drugs and was having dependency problems. While use of alcohol or street drugs was not perceived as problematic on the West Coast, over 58% reported using prescription drugs for self-treatment of illnesses other than those targeted by the prescription. When prescription drugs were misused by women, it was most frequently to get an altered state, or "street drug effect". Numerous stressors influence Cambodian women during the pressures of acculturation to the U.S. lifestyle. Some may turn to self-medication in the form of alcohol, prescription sleeping pills, or other drugs. A better understanding of how and why these women make coping choices is needed.

Cultural themes in family stress and violence among Cambodian refugee women in the inner city.

Cambodian refugee women frequently face the cumulative trauma of war experiences and cultural adaptation to the American inner-city environment. This qualitative study investigated cultural beliefs, coping strategies, and management of family stress among Cambodian refugee women living in the inner-city environment. Focused and open-ended interviews were conducted in the informants' homes using the Cambodian language. Stressful and violent events were managed by nonconfrontation and withdrawal. These two themes are hypothesized as the culturally identified means by which inner-city Cambodian refugee women control and harmonize situations of stress. Further study is needed to develop the theoretical base for developing culturally sensitive nursing intervention strategies with this high risk population.

Stress in Cambodian refugee families.

Southeast Asians are a rapidly growing, culturally varied group needing physical and mental health services. The sources, manifestations, and coping strategies associated with stress experienced by this group are not well documented. Interviews were conducted with 120 Cambodian women in this comparative descriptive study to identify their perceptions of stress-related factors confronting families. Memories of the war, financial concerns, and family problems were frequently cited. Somatic manifestations were the most common symptoms. A general sense of inability to cope with stress suggests the need for health care providers to be sensitive to undeclared problems.

Themes in managing culturally defined illness in the Cambodian refugee family.

The Cambodian (Khmer) refugee population in America is considered to be the Indochinese refugee population at highest risk for stress-related health problems resulting from traumatic physical and emotional experiences during the Khmer Rouge holocaust in this Southeast Asian country. In this study, koucharang, described as "thinking too much," was identified by informants as a culture-bound syndrome in response to the violence experienced in Cambodia. It is characterized by behavioral changes and somatic complaints. This study identified two cultural themes used by Cambodian families in the management of this disabling condition. The research is a follow-up from a prior study that examined cultural themes in health care decision making among Khmer women. This study of themes in family management of culturally defined illness was conducted with 120 Cambodian refugee women in Long Beach, California and Lowell, Massachusetts. These geographical areas were selected because the Khmer refugee population in America has relocated primarily to the low-income inner-city areas of southern California and Massachusetts. Nursing strategies for utilizing the identified cultural themes in intervening with the Cambodian family are identified. The community health nurse can build upon the strength of these themes and the resulting culturally dictated practices as he or she provides supportive counseling and health promotion to this highly traumatized population. The emotional risks to the community health nurse in working with the Cambodian refugee family are discussed in the context of maintaining self-integrity in the face of overwhelming tragedy.

Barriers to health care for Vietnamese refugees.

This study was undertaken to determine the dynamics of why Vietnamese refugees may not optimally use existing health services in the United States. A random sample of 75 refugees was interviewed by a bilingual translator. Multivariate analysis of variance was used to analyze the effects of time of arrival on whether the following are barriers to care: not having a translator available in health care facilities, feeling understood by health care providers, being able to understand the written and verbal instructions of providers, and not having a primary provider. The hypothesis, that time-of-arrival groups would differ significantly on these variables, was supported (F = 4.81; df = 8,136; P less than .001). Concern about not having a translator in health care facilities ranked first in distinguishing the groups (F = 17.09; df = 2.71; P less than .001), followed by primary provider (F = 5.68; df = 2.71; P less than .01), feeling understood by the provider (F = 5.15; df = 2.71; P less than .01), and being able to understand written and verbal instructions given by the provider (F = 4.25; df = 2.71; P less than .05). The time-of-arrival groups also differed significantly on supplemental analyses. Subjects expressed willingness to seek more frequent health care if translators were available in health care facilities (F = 18.22; df = 2.72; P less than .001) and to change health care sites to gain a translator (F = 13.74; df = 2.72; P less than .001).