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Biomedical subjects

G W Small

Publications and source records attributed to G W Small.

At least 91 records · Page 5Linked to original sources
PubMed1995

Predictors of cognitive change in middle-aged and older adults with memory loss.

OBJECTIVE: Previous longitudinal studies of age-related memory loss have focused on objective neuropsychological measures that predict subsequent cognitive change, yet brain metabolic function, self-perception of memory loss, and other measures may also be sensitive indicators of cognitive change. To determine such baseline predictors of change, the authors made longitudinal assessments of middle-aged and older adults with memory loss. METHOD: Forty-two persons (mean age = 60 years, range = 43-81) with memory complaints received comprehensive baseline assessments, including subjective neuropsychological measures, objective measures of visual-spatial memory (the Benton Visual Retention Test) and verbal memory (the Buschke-Fuld Selective Reminding Test), and positron emission tomography scans to determine neocortical glucose metabolism. At an average follow-up of 3 years, the objective neuropsychological measures were again used to quantify the degree of cognitive change. RESULTS: Multiple regression analyses indicated that parietal asymmetry, sex of the subject, and baseline visual-spatial memory score were significant predictors of change in visual-spatial memory; level of education and baseline verbal memory score predicted change in verbal memory. Other neocortical asymmetry scores, age, family history of Alzheimer's disease, cerebral atrophy, and self-ratings of use of mnemonics were not significant predictors of change. CONCLUSIONS: Measures of cerebral metabolism, objective memory performance, sex, and education may predict subsequent cognitive change in middle-aged and older persons with memory loss. Also, the parietal asymmetry found in persons with questionable dementia that progresses to probable Alzheimer's disease may be present very early in the course of age-related cognitive decline.

Adult↗
PubMed1995

The management of depression and anxiety in the elderly.

The most common psychiatric disorders in later life, with the exception of dementia, are depression and anxiety. Often underdiagnosed or simply accepted with resignation as an inevitable part of aging or as an unavoidable complication of other constitutional illnesses, these disorders contribute to excess disability in older patients and further compromise their quality of life. This report discusses depression and anxiety in the growing elderly population--its prevalence, detection methods, diagnostic considerations, and present interventions.

Age Factors↗
PubMed1994

1-beta-D-Arabinofuranosylcytosine stimulates ceramide and diglyceride formation in HL-60 cells.

The effect of 1-beta-D-arabinofuranosylcytosine (ara-C) on phospholipid metabolism was investigated in HL-60 cells. Treatment of cells with ara-C resulted in a time- and dose-dependent increase in the mass of ceramide and diglyceride. When cells were treated with 10 microM ara-C, an increase in the mass of ceramide and diglyceride was detectable at 5 min and reached a plateau at 30 min with a 2-fold increase compared to control cells. Treatment of cells with 10 microM ara-C resulted in the activation of neutral sphingomyelinase with a peak at 30 min that represented a 2-fold increase in specific activity. ara-C also increased expression of the transcription factor NF-kappa B which is related to the control of monocyte differentiation. These findings suggest that ara-C activates phospholipid hydrolytic pathways to generate second messengers that control gene expression and differentiation in the HL-60 cell line.

Cell Differentiation↗
PubMed1994

A sudden outbreak of illness suggestive of mass hysteria in schoolchildren.

OBJECTIVE: To clarify factors contributing to mass illness of sudden onset by studying an outbreak that was apparently triggered by a gaseous odor and that involved a rapid, extensive response by school and fire officials. SETTING: Urban elementary school. MAIN OUTCOME MEASURE: A standardized student questionnaire was designed to identify potential illness predictors. DESIGN: Four weeks following the outbreak, public health officials distributed the questionnaire to all students in regular classes in grades 3 through 6 (N = 319), representing 46% of the estimated 680 students present the day of the outbreak. RESULTS: Seventy-seven percent of the students who completed the questionnaire reported that they experienced physical symptoms during the epidemic. A stepwise regression analysis demonstrated several independent variables that predicted the severity of illness, including the intensity of the odor smelled during the outbreak (P < .0001), becoming sick after the fire trucks arrived (P < .0001), and believing in an environmental cause for the illness (P < .002). CONCLUSIONS: These results indicate that both psychological and environmental factors, real or perceived, may contribute to sudden-onset epidemics of hysteria. Moreover, the response intervention of officials may influence the extent of such outbreaks. Early recognition of psychological causes and dispersion of groups at risk could reduce morbidity and associated health care costs.

Child↗
PubMed1994

Evaluation of three methods for the rapid identification of Staphylococcus aureus in blood cultures.

A total of 445 blood cultures containing Gram-positive cocci in clusters were tested for the presence of Staphylococcus aureus with the Accuprobe, heat-stable thermonuclease, and latex agglutination using Staphaurex. The results show that the Accuprobe, thermonuclease, and Staphaurex correctly identified 95, 96, and 62 of the 100 specimens containing S. aureus. The corresponding specificity for the methods was 99.1%, 100%, and 98.5%, respectively.

Bacteremia↗
PubMed1994

Age-associated memory loss: initial neuropsychological and cerebral metabolic findings of a longitudinal study.

To determine the relationships between clinical and brain function in persons with a familial risk for Alzheimer's disease, the authors assessed subjective and objective cognitive abilities, mood state, and cerebral glucose metabolism (using positron emission tomography) in 43 persons with age-associated memory impairment, with and without first-degree relatives with a clinical diagnosis of Alzheimer's disease. Subjective complaints of memory loss, mood state ratings, and objective memory measures were similar in persons with a family history of Alzheimer's disease (n = 29) compared to those without such a history (n = 14). Metabolic ratios in the frontal regions correlated with a decrease in a specific type of subjective memory complaint (mnemonics usage; p < .001) and some mood state ratings. These results indicate that parietal and temporal hypometabolism is not evident in persons with mild age-related memory complaints, even when such subjects have a familial risk for Alzheimer's disease. Moreover, self-reports of mnemonics usage may be sensitive indicators of decreased frontal lobe function. Longitudinal study will determine whether such clinical and metabolic measures will predict eventual disease progression.

Adult↗
PubMed1994

Central nervous system IgG synthesis rates in Alzheimer disease: possible differences in early-onset and late-onset subgroups.

Central nervous system IgG synthesis rates were determined for 51 patients with autopsy-confirmed Alzheimer disease and 23 age-matched controls. Rates were no different between patients and controls when overall groups were compared. Age-at-dementia-onset data were available on 37 patients. Comparisons of 11 early-onset (< 65 years of age) patients with 26 late-onset patients revealed significantly increased intrathecal IgG synthesis rates for the late-onset group. These results suggest that IgG synthesis may be a contributing pathogenic factor in a subgroup of patients with late-onset Alzheimer disease.

Age Factors↗
PubMed1994

Factitious hemoptysis. Adding to the differential diagnosis.

BACKGROUND: We report a dramatic case of factitious hemoptysis in a 36-year-old black man who presented with hemoptysis and chest pain. METHODS: After an exhaustive evaluation, including many invasive procedures, we discovered that the patient's complaints were fabricated, although the method used to simulate hemoptysis was not determined. Documentation was obtained of at least 23 other hospital admissions with similar complaints. During these hospitalizations, numerous diagnostic procedures were performed, including 16 fiberoptic bronchoscopies and 3 cardiac catheterizations, with negative results. RESULTS: Review of 11 other reported cases of factitious hemoptysis reveals that these patients are generally young (mean age, 32 years; range, 21 to 47 years) and often health-care workers (4 of 12 cases) and that the method of simulating hemoptysis, if discovered, usually involves a self-inflicted wound (5 cases). CONCLUSION: A factitious cause should be considered in the differential diagnosis of hemoptysis of unclear etiology, especially when the medical history or the patient's behavior is unusual.

Adult↗
PubMed1993

Near-infrared spectroscopic measurement of glucose in a protein matrix.

A method is described for measuring clinically relevant levels of glucose in a protein matrix by near-infrared (near-IR) absorption spectroscopy. Results from an initial screening of major blood constituents identify protein as a major potential interference to the near-IR measurement of glucose in blood. The interference by protein is caused by relatively high concentrations coupled with strong near-IR absorption bands between 5000 and 4000 cm-1 (2.0-2.5 microns). Calibration models based on a simple univariate calibration procedure are not capable of providing accurate glucose concentrations from an independent set of prediction spectra. By use of the multivariate technique of partial least squares (PLS) regression, glucose concentrations can be determined with a 0.35 mM (6.3 mg/dL) standard error of prediction. The spectral range for this calibration model extends from 4600 to 4200 cm-1, and the optimum number of PLS factors is 14. In addition, calibration models based on a combination of digital Fourier filtering and PLS regression have been constructed and evaluated. Superior calibration models are obtained by using a preprocessing digital filtering step to remove spectral features not associated with glucose. The best overall calibration model was obtained by using a Gaussian-shaped Fourier filter defined by a mean position of 0.03f and standard deviation of 0.007f coupled with a 12-factor PLS regression computed over the spectral range from 4600 to 4200 cm-1. This model provided a standard error of prediction of 0.24 mM (4.3 mg/dL) for an independent set of prediction spectra.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Glucose↗
PubMed1993

Strategies for coupling digital filtering with partial least-squares regression: application to the determination of glucose in plasma by Fourier transform near-infrared spectroscopy.

Protocols are established for coupling digital filtering techniques with partial least-squares (PLS) regression for use in constructing multivariate calibration models from Fourier transform near-infrared absorbance spectra. Calibration models are developed to predict glucose concentrations in bovine plasma samples. Employing a calibration data set of 300 spectra collected from 55 plasma samples and 3 plasma lots, individual calibration models are developed based on four spectral ranges selected from the region 5000-4000 cm-1. A separate test set of 69 spectra collected from 14 plasma samples is used to evaluate the computed models. Gaussian-shaped bandpass digital filters are implemented by use of Fourier filtering techniques and employed to preprocess spectra to remove variation due to the background absorbance of the plasma matrix. PLS regression is used with the filtered spectra to compute calibration models for glucose. The optimization of the filter bandpass parameters is explored through the use of response surface methods. Through these optimization studies, calibration models are developed that achieve standard errors of estimate and standard errors of prediction in the range 0.4-0.5 mM across the concentration range of 2.5-25.5 mM. It is determined that the use of digital filtering as a preprocessing step significantly improves the performance of the resulting calibration models, minimizes the importance of spectral range in the calibration model development, and reduces the required number of PLS factors in each model.

Animals↗
PubMed1993

Gene dose of apolipoprotein E type 4 allele and the risk of Alzheimer's disease in late onset families.

The apolipoprotein E type 4 allele (APOE-epsilon 4) is genetically associated with the common late onset familial and sporadic forms of Alzheimer's disease (AD). Risk for AD increased from 20% to 90% and mean age at onset decreased from 84 to 68 years with increasing number of APOE-epsilon 4 alleles in 42 families with late onset AD. Thus APOE-epsilon 4 gene dose is a major risk factor for late onset AD and, in these families, homozygosity for APOE-epsilon 4 was virtually sufficient to cause AD by age 80.

Aged↗
PubMed1993

Clinical, neuroimaging, and environmental risk differences in monozygotic female twins appearing discordant for dementia of the Alzheimer type.

OBJECTIVE: The study of monozygotic twins can elucidate possible environmental causes for a disease in genetically identical subjects. To this end, we studied a pair of monozygotic female twins appearing discordant for dementia of the Alzheimer type (DAT). DESIGN: Clinical and neuroimaging findings were compared in terms of potential environmental risk factors. SETTING: University referral center. PARTICIPANTS: An 81-year-old female monozygotic twin pair. OUTCOME MEASURES: Clinical assessments, standardized rating scales, and brain imaging studies, including magnetic resonance imaging, positron emission tomography, and electroencephalography, were performed. Neuropsychological tests were performed initially and after 1 year. RESULTS: Although DAT was confirmed clinically in only one twin, neuropsychological and brain imaging studies suggested that the unaffected twin may be developing the prodrome of DAT. The twins' varied life histories suggest that environmental risk factors may contribute to apparent discordance for DAT and possible delay in disease onset for the currently nondemented twin. CONCLUSIONS: These results suggest that both genetic and nongenetic factors influence disease onset and expression. Moreover, review of previous reports of monozygotic twin pairs concordant or discordant for Alzheimer's disease, with adequate family history data, suggest a pattern indicating interactions among age at dementia onset, sex, and familiarity. Such patterns point to hypotheses regarding neurobiologically meaningful Alzheimer's disease subgroups.

Aged↗
PubMed1992

Reliability of drawing regions of interest for positron emission tomographic data.

We determined interrater reliability for two raters who independently used a standard protocol to draw regions of interest (ROIs) on F-18 fluorodeoxyglucose positron emission tomographic data acquired from eight patients with mild to moderate memory impairment. Intraclass correlation coefficients for region sizes (total pixel number) varied among anatomical ROIs (RIs from 0.324 to 0.935). However, correlations calculated from relative metabolic rates (normalized average counts) were consistently high (RI > or = 0.954). The raters also showed high agreement for region recognition on each image plan (kappa = 0.978). These results suggest that rater disagreements in ROI margins have minimal impact on average count densities used to calculate metabolic rates.

Aged↗
PubMed1992

Evaluation of commercial and standard methodology for determination of oxacillin susceptibility in Staphylococcus aureus.

Agar dilution with and without 4% NaCl, broth microdilution with 2% NaCl, the dried MicroScan Rapid Positive MIC 1 panel (Baxter Health Care Corp., West Sacramento, Calif.), the Vitek GPS-SA card (Vitek Systems, Hazelwood, Mo.), and the oxacillin agar screen plate were compared with a DNA probe encoding the mec gene for their abilities to detect oxacillin resistance in 506 clinical isolates of Staphylococcus aureus. The results of testing for the mec gene showed that there were 254 oxacillin-resistant and 252 oxacillin-susceptible isolates of S. aureus. There were 14.2% very major errors with Vitek (a resistant isolate was interpreted as susceptible) and 6.7% very major errors with MicroScan. Fewer major errors were seen: 0.8% with MicroScan (a susceptible isolate was interpreted as resistant) and 0.4% with Vitek. No very major errors but 2.4% major errors occurred by agar dilution with 4% NaCl supplementation, whereas there were 0.8% very major and 0.4% major errors without 4% NaCl supplementation. By broth microdilution there were 2.0% very major and 0.8% major errors. The results of the oxacillin agar screen plate method were 100% concordant with those of the mec gene probe method.

DNA Probes↗