Acid-base changes in cerebrospinal fluid of infants with metabolic acidosis.
Explore the source record for details and available documents.
Acid-Base Equilibrium↗
Biomedical subjects
M S Albert
Publications and source records attributed to M S Albert.
Acid-base equilibrium of blood in normal infants.
Explore the source record for details and available documents.
Acid-Base Equilibrium↗
Aqueous shift reagents for high-resolution cation NMR. VI. Titration curves for in vivo 23Na and 1H2O MRS obtained from rat blood.
Frequency shift/concentration calibration curves applicable to the use of shift reagents (SRs) for in vivo 23Na MRS studies can be obtained from experiments with whole blood. Here, they are reported for titrations of rat blood with the SRs DyTTHA3- and TmDOTP5-. There are a number of considerations that must be made in order to derive accurate calibration curves from the experimental data. These include the effects of bulk magnetic susceptibility (BMS, since the SRs are paramagnetic), the effects of water flux (since addition of the SR stock solution to blood renders the plasma hyperosmotic), and the consequences of restricted distribution of the SR anion in the erythrocyte suspension. We give in some detail the BMS shift theory that obtains in this case and show also how it applies to excised perfused organ as well as in vivo studies. Also, we report significant effects of adjuvant Ca2+ additions in the TmDOTP5- titrations. These are very important to the successful use of this SR in vivo. Finally, our considerations of BMS lead naturally to an understanding of its manifestations in the shifts of the 1H2O resonance frequencies of cell suspensions and tissues induced by SRs. Since these are being increasingly reported, and often misinterpreted, we devote an experiment and some discussion to this subject. We show that this phenomenon cannot be used to quantitatively discriminate intra- and extracellular 1H2O signals.
Animals↗
The pattern of age-related differences in electrophysiological activity of healthy males and females.
Age-related differences in quantified electrophysiological measures were examined in 202 subjects (109 females; 93 males) ages 30-80 all of whom were judged to be optimally healthy on a wide variety of criteria. The study utilized both absolute and relative measures from EEG spectral analysis as well as additional measures from long latency-evoked potentials. The same findings were noted for the 109 newly studied females as were reported for 63 previously studied male subjects. Results indicate that there is a broad trend for decreased EEG slow and increased fast activity with age, however, some of the measures change linearly and others are best represented by nonlinear functions. There is no decade where activities remain stable. Overall the pattern of change for males and females is similar, however, gender differences in both the EEG and EP data were present. The females had higher magnitudes for almost all absolute spectral and fast relative spectral measures. However, females demonstrated lower absolute alpha amplitude, lower relative slow activity, and lower late-latency EP data. Moreover, the absolute slow activity measure showed a gender X age interaction, indicating that the females had a different change in pattern of activity with increasing age than the males. Thus, gender-related findings were complex and could not be expressed as simple differences in overall amplitude. Age-related change is not a simple linear process but differs for differing EEG spectral bands, relative, and absolute spectral measures and for males and females. The overall findings contradict the common wisdom that EEG and alpha slow with age and that age related EEG change is on a continuum with findings in Alzheimer's disease where increased slowing predominates.
Adult↗
Effects of age upon interhemispheric EEG coherence in normal adults.
Age-related differences in quantified electrophysiological measures of interhemispheric EEG coherence were studied in 371 subjects (171 males and 200 females), ages 20-80, all of whom were judged to be optimally healthy. Principal components analysis (PCA) was performed on interhemispheric coherence of Laplacian referenced data from eight homologous left-right electrode pairs, from 0.5 to 32 Hz. Regression procedures, using signals from artifact monitoring channels, were used to minimize effects of eye movement and muscle artifact. Forty-six factors described 80% of the total variance, with electrode location the primary source of communality in factor formation. Within 350 right-handed subjects, results indicated a broad trend for decreased interhemispheric coherence with advancing age. Using canonical correlation, the coherence-based factors also successfully predicted spectral variables, previously found to maximally illustrate age-related EEG desynchronization. We speculate that age-related reduction of interhemispheric coherence may in part explain age-related EEG desynchrony and stems from age-related reduction of cortical connectivity. Gender differences of interhemispheric coherence were also evident. Females demonstrated higher interhemispheric coherence than males. Within a smaller subpopulation of 63 subjects (21 left and 42 right handed), there was a gender-by-handedness interaction, with higher interhemispheric coherence in right-handed females than right-handed males and the reverse in left-handed male and female subjects.
Adult↗
Perfusion abnormalities in prodromal AD.
Cerebral perfusion abnormalities in patients with established Alzheimer's disease (AD) are most commonly seen in the temporoparietal cortex. As the disease progresses, this perfusion pattern is increasingly prevalent. Recently, investigators have begun to examine the patterns of perfusion among individuals at risk for AD. To date, such studies have been conducted either in individuals who have a progressive memory difficulty but do not yet meet clinical criteria for AD, or in individuals with a genetic risk factor or family history of AD, either with or without a memory problem. These latter studies suggest that a set of brain regions show decreased perfusion during the prodromal phase of AD, and that a brain network or networks with multiple nodes is affected early in the course of AD. These perfusion abnormalities may also shed light on how AD progresses during the prodromal phase of disease and may ultimately lead to improved diagnosis or methods of monitoring response to treatment.
Alzheimer Disease↗
Special behavioral paradigms in animals to study age-related changes in memory.
Animal models are important to understand age-related changes in humans. However, the models do not always agree about the effects of aging on memory, and some of the results with animals are different from those with humans. Points of similarity and difference are discussed, indicating some directions for future research.
Aging↗
Temporoparietal electrophysiological differences characterize patients with Alzheimer's disease: a split-half replication study.
One hundred and eighty nine subjects were examined by quantified EEG (qEEG) during the resting awake state. Sixty subjects had probable Alzheimer's disease (AD) and were mild to moderately impaired. There were 129 healthy controls. Differences between patients and controls by topographic mapping demonstrated a pattern of group difference maximal posteriorly, primarily in posterior temporal and/or parietal regions. Frontal regions were much less frequently involved. Long-latency evoked potential derived difference showed similar spatial patterns of difference. By EEG spectral analysis, theta was increased and beta decreased for the AD patients. In addition, the qEEG measures were significantly correlated with neuropsychological test scores related to abilities that are impaired in the early stages of disease, such as delayed recall and verbal fluency. To assess replicability the population was split in half. Regions of interest derived from the first half provided numerical measures for discriminant function analysis. A discriminant function, derived from the first half, correctly identified 86% of all second-half subjects (91% controls, 77% AD).
Aged↗
Measurement of 129Xe T1 in blood to explore the feasibility of hyperpolarized 129Xe MRI.
OBJECTIVE: The major obstacle to the use of 129-xenon (I = 1/2) as a new source of contrast in magnetic resonance is its low sensitivity. The hyperpolarized 129Xe-MRI technique using laser optical pumping of rubidium promises to resolve this problem. The potential of xenon-based MRI for the body tissues other than the lung air spaces depends on the 129Xe polarization lifetime (T1) in the blood at a magnetic field of commonly available clinical MRI systems. MATERIALS AND METHODS: Xenon with natural abundance of 129Xe (26%) was dissolved in human blood and studied at 36 degrees C in a 2.35 T 40 cm bore MRI spectrometer (27.6 MHz). Zeeman relaxation (T1) of six blood samples was measured by the progressive saturation method for periods of 4-8 h each. RESULTS: NMR spectra revealed two peaks at 216.0 ppm (A) and 194.0 ppm (B) relative to the xenon gas above the blood volume. Assignment and 129Xe T1 values were 4.5 +/- 1 s for red blood cells (A), 9.6 +/- 2 s for plasma (B) and 11.9 +/- 1.6 s for xenon gas at atmospheric oxygen pressure. Xenon dissolved in distilled water appears at 189.8 ppm and has T1 = 26.3 +/- 1.4 s. CONCLUSION: These relaxation times, though shorter than expected, are comparable to the transport time of blood, and are long enough to encourage use of hyperpolarized xenon for MRI studies in tissues, in addition to lung.
Humans↗
The delirium symptom interview: an interview for the detection of delirium symptoms in hospitalized patients.
To study delirium in hospitalized elderly, a delirium symptom interview (DSI) was developed by an interdisciplinary group of investigators. This interview was administered in an acute care hospital to 50 patients who were over the age of 65 years. Results from the interview were compared to assessments of major symptoms of delirium made independently by a neurologist and a psychiatrist. This interview had good validity and reliability. The sensitivity of the DSI was .90 and the specificity was .80, when compared with the clinical judgment of a psychiatrist and neurologist. Interrater reliability, using lay interviewers, was .90 for the detection of major symptoms of delirium. These results indicate that the DSI could be used by lay interviewers to assess reliably the symptoms of delirium.
Aged↗
Survival and stress: tips from the diary of an educationally mobile handicapped nurse.
Explore the source record for details and available documents.
Adult↗
Health indices as predictors of cognition among older African Americans: MacArthur studies of successful aging.
Using cross-sectional and longitudinal data from the MacArthur Successful Aging Study, this paper examines associations between cognition and indices of health in 224 elderly African Americans 70 to 79 years of age at initial interview. The results indicated that greater average peak expiratory flow was predictive of better cognitive performance at the first interview. One longitudinal analysis showed that gender was the only significant predictor of change (change as a continuous variable) with women tending to slightly improve their cognitive performance over time. When change was treated as a dichotomous variable (e.g., a decline of 6 or more points), lower levels of average peak expiratory flow and education were predictive of decline, and positive self-ratings of current health and changes in health in the past year were important factors in the improvement of cognitive performance. The results indicate that, in addition to education, health is an important predictor of the status and course of cognitive functioning in older African Americans.
Black or African American↗