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PubMed1992

Prevalence of dementia and probable senile dementia of the Alzheimer type in the Framingham Study.

We determined the prevalence of dementia and probable senile dementia of the Alzheimer type (SDAT) for biennial Exam 17 of the Framingham cohort (1982/1983). The prevalence of dementia was 30.5/1,000 for men and 48.2/1,000 for women and increased with advancing age. Cases of probable SDAT constituted 55.6% of all dementia cases. THe prevalence of SDAT was 11.7/1,000 for men and 30.1/1,000 for women and also increased with advancing age. Prevalence of dementia and probable SDAT were greater for women than men. The female:male ratio of prevalence for cohort members 75 years of age and older was 1.8 for all cases of dementia and 2.8 for cases of probable SDAT.

Adult↗

PubMed1993

Incidence of dementia and probable Alzheimer's disease in a general population: the Framingham Study.

OBJECTIVE: To determine the incidence of dementia and Alzheimer's disease (AD) in a general population sample. BACKGROUND: Utilizing subjects in the Framingham Study cohort determined to be free of dementia in 1976 to 1978, or on biennial examination 17 in 1982, all new cases of dementia arising in this cohort over a maximum of 10 years of follow-up were ascertained. METHODS: On biennial examination 14/15, a screening neuropsychologic examination was administered to 2,117 subjects, and cases of probable prevalent dementia were identified. Beginning on examination 17 and on all successive biennial examinations, a Mini-Mental State Examination was administered. Subjects previously free of dementia and falling below age-education levels were evaluated by a neurologist and neuropsychologist to determine if dementia was present and to ascertain the dementia type using standard criteria. RESULTS: Five-year incidence of dementia increased with age, doubling in successive 5-year age groups. Dementia incidence rose from 7.0 per 1,000 at ages 65 to 69 to 118.0 per 1,000 at ages 85 to 89 for men and women combined. Incidence of probable AD also doubled with successive quinquennia from 3.5 at ages 65 to 69 to 72.8 per 1,000 at ages 85 to 89 years. Incidence of dementia and of probable AD did not level off with age and was not different in men and women. CONCLUSIONS: In a general population sample, we determined incidence of dementia and of probable AD and will use these incident cases for study of precursors and natural history in this elderly cohort, which has been under close surveillance for over 40 years.

Adult↗

PubMed1996

Predictors of mortality in patients diagnosed with probable Alzheimer's disease.

OBJECTIVE: We sought to identify factors associated with mortality in persons recently diagnosed with probable Alzheimer's disease (AD). BACKGROUND: Predicting mortality in AD in needed both in patient care and public health planning. Previous studies have identified several factors which contribute to mortality in AD, but few longitudinal studies of population-based cohorts exist. METHODS: In a longitudinal follow-up study 327 patients with newly diagnosed probable AD (mean Mini-Mental State Examination [MMSE] score of 20) from a large, stable health maintenance organization were identified. Demographic characteristics, dementia severity, and comorbid conditions were identified at enrollment. Patients were followed longitudinally (median 3.3 years, total 898 person-years). Baseline characteristics were used to predict survival in univariate and multivariate models. RESULTS: Increased mortality was seen in patients with probable AD (9.0 deaths per 100 person-years) compared with the community population adjusted for age and gender (4.3 deaths per 100 person-years). On univariate analysis we found increased age, male gender, impairment on MMSE or Blessed dementia rating scale (DRS), rate of MMSE decline, wandering or agitation, vascular disease, and sensory impairment affecting the ability to read or hear to be moderately associated with decreased survival. After adjusting for age and gender in a multivariate model, Blessed DRS score and sensory impairment affecting the ability to read were independently associated with decreased survival. CONCLUSIONS: Short-term mortality is increased in patients newly diagnosed with probable AD. Measures of dementia severity, measures of general debility, and vascular disease are associated with increased mortality. Of these, general debility and sensory impairment were more strongly associated with shortened survival.

Aged↗

PubMed2003

Clinical outcomes of possible versus probable Alzheimer's disease.

OBJECTIVE: To determine whether Alzheimer's disease (AD) associated with comorbidities or atypical features (possible AD) is marked by differences in clinical course and outcomes compared with uncomplicated AD (probable AD). METHODS: Annual evaluations were made of patients with AD, for up to 11 years. Six hundred forty subjects with AD were clinically classified into two groups: 1) possible AD (n = 208), and 2) probable AD (n = 432). Data on demographics, Mini-Mental State Examination (MMSE), Short Blessed Test (SBT), psychometric performance, and Clinical Dementia Rating (CDR) were collected at baseline. Kaplan-Meier survival curves and Cox proportional hazards models were conducted to evaluate whether possible AD would have different outcomes on dementia progression, nursing home placement, and death compared with probable AD. RESULTS: The possible AD group was slightly younger and less well educated than the probable AD group, but there were no group differences at baseline in MMSE, SBT, and CDR scores. Controlling for age and education, the possible AD group had poorer baseline psychometric performance (p = 0.022). There were no group differences, however, for rate of dementia progression, nursing home admission, and death. CONCLUSIONS: Comorbidities and atypical features in this sample of patients with Alzheimer's disease did not substantially affect dementia outcomes. The primary determinant of the clinical course of dementia in this sample was the presence of clinically diagnosed Alzheimer's disease, independent of the presence or absence of comorbidities or atypical features. Therefore, patients with possible Alzheimer's disease may be considered for inclusion in investigations of Alzheimer's disease, including clinical trials, to improve the generalizability of the findings.

Aged↗

PubMed2006

Livedoid skin reaction probably due to imatinib therapy.

OBJECTIVE: To report 3 cases of skin rash with a peculiar livedoid pattern that were probably associated with imatinib therapy. CASE SUMMARY: In the first case, a 74-year-old male diagnosed with Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML), treated with imatinib 400 mg/day, developed a skin eruption with a livedoid pattern. Systemic corticosteroids were started, and skin lesions improved. The second case involved a 66-year-old male with Ph+ CML who was treated with imatinib 600 mg/day. After initiation of this treatment, he developed a skin rash with a livedoid pattern. The drug treatment was discontinued and then reintroduced. Topical corticosteroid treatment was started, resulting in total remission of the skin lesions. When the imatinib dose was progressively reintroduced, the skin lesions recurred. The patient died as a result of the progression of his disease. In the third case, a 43-year-old male with Ph+ acute lymphoblastic leukemia was treated with imatinib 600 mg/day. After a few days of treatment, the patient developed a skin rash with a livedoid pattern. He died as a result of probable septic shock. DISCUSSION: Imatinib is a tyrosine kinase receptor inhibitor that inhibits BCR/ABL tyrosine kinase. There have been several published articles on cutaneous adverse reactions related to imatinib therapy. The most common cutaneous adverse event of imatinib is a rash with variable clinical presentation. The Naranjo probability scale indicated a probable relationship between imatinib and the rash in all 3 cases reported here. CONCLUSIONS: Adverse reactions to imatinib that affect the skin occur frequently. They are strongly dose dependent, self-limiting, or easily managed by lowering the dose of imatinib and, if necessary, prescribing short-term therapy with a systemic corticosteroid. Clinicians should monitor patients taking imatinib and institute treatment quickly if a rash develops.

Adult↗

PubMed2006

Probability-based differential normalized fluorescence bivariate analysis for the classification of tissue autofluorescence spectra.

Differential normalized fluorescence (DNF) is an efficient and effective method for the differentiation of normal and cancerous tissue fluorescence spectra. The diagnostic features are extracted from the difference between the averaged cancerous and averaged normal tissue spectra and used as indices in tissue classification. In this paper, a new method, probability-based DNF bivariate analysis, is introduced based on the univariate DNF method. Two differentiation features are used concurrently in the new method to achieve better classification accuracy. The probability of each sample belonging to a disease state is determined with Bayes decision theory. This probability approach classifies the tissue spectra according to disease states and provides uncertainty information on classification. With a data set of 57 colonic tissue sites, probability-based DNF bivariate analysis is demonstrated to improve the accuracy of cancer diagnosis. The bivariate DNF analysis only requires the collection of a few data points across the entire emission spectrum and has the potential of improving data acquisition speed in tissue imaging.

Analysis of Variance↗

PubMed2000

Iodine-125 decay in a synthetic oligodeoxynucleotide. I. Fragment size distribution and evaluation of breakage probability.

Lobachevsky, P. N. and Martin, R. F. Iodine-125 Decay in a Synthetic Oligodeoxynucleotide. I. Fragment Size Distribution and Evaluation of Breakage Probability. Incorporation of (125)I-dC into a defined location of a double-stranded oligodeoxynucleotide was used to investigate DNA breaks arising from decay of the Auger electron-emitting isotope. Samples of the oligodeoxynucleotide were also labeled with (32)P at either the 5' or 3' end of either the (125)I-dC-containing (so-called top) or opposite (bottom) strand and incubated in 20 mM phosphate buffer or the same buffer plus 2 M dimethylsulfoxide at 4 degrees C during 18-20 days. The (32)P-end-labeled fragments produced by (125)I decays were separated on denaturing polyacrylamide gels, and the (32)P activity in each fragment was determined by scintillation counting after elution of fragments from the gel. The relative fragment size distributions were then normalized on a per decay basis and converted to a distribution of single-strand break probabilities as a function of distance from the (125)I-dC. The results of three to five experiments for each of eight possible combinations of labels and incubation conditions are presented as a table showing the relative numbers of (32)P counts in different fragments as well as graphs of normalized fragment size distributions and probabilities of breakage. The average numbers of single-strand breaks per (125)I decay are 3. 3 and 3.7 in the top strand and 1.3 and 1.5 in the bottom strand with and without dimethylsulfoxide, respectively. Every (125)I decay event produces a break in the top strand, and breakage of the bottom strand occurs in 75-80% of the events. Thus a double-strand break is produced by (125)I decay with a probability of approximately 0.8.

Base Sequence↗

PubMed1985

Component probability and component reinforcer rate as biasers of free-operant detection.

Six pigeons were trained on multiple schedules whose components were concurrent variable-interval extinction and concurrent extinction variable-interval schedules. In Experiments 1a and 1b the stimuli signaling the components were two different light intensities, and in Experiments 2a and 2b they were two identical intensities. The components of the multiple schedule changed probabilistically after each reinforcer. In Experiments 1a and 2a, the probability of presenting the components was varied over five conditions and a replication. In Experiments 1b and 2b, the component probability was .5 and the component reinforcer rates were varied systematically over five conditions and a replication. The data, analyzed according to the Davison-Tustin behavioral detection model, confirmed that the discriminability of the stimuli signaling the components was high when the stimuli were different, and low when the stimuli were the same. Discriminability, measured by log d, was unaffected by component probability variation and by component reinforcer-rate variation. When discriminability was high, bias, or the response allocation between the two keys, was more strongly affected by variation of reinforcer rate within components than by variation of component probability, but the reverse was found when discriminability was low. The results suggest that free-operant detection performance is controlled by the rates of reinforcers in periods of time in which stimuli signal differential contingencies. These periods comprise the components when the component stimuli are discriminable, and comprise the total session when the components are indiscriminable. An extension of the Davison-Tustin behavioral detection model that incorporates these results is presented.

Journal Article↗

PubMed1990

Motivational effects of smoked marijuana: behavioral contingencies and low-probability activities.

Six adult male research volunteers, in two groups of 3 subjects each, lived in a residential laboratory for 15 days. All contact with the experimenters was through a networked computer system, and subjects' behavior was monitored continuously and recorded. During the first part of each day, they were allowed to socialize. Two cigarettes containing active marijuana (2.7% delta 9-THC) or placebo were smoked during the private work period and the period of access to social activities. Three-day contingency conditions requiring subjects to engage in a low-probability work activity (instrumental activity) in order to earn time that could be spent engaging in a high-probability work activity (contingent activity) were programmed during periods of placebo and active-marijuana smoking. During placebo administration, the contingency requirement reliably increased the amount of time that subjects spent engaged in the low-probability instrumental activity and decreased the time spent engaged in the high-probability activity. During active-marijuana administration, however, the increases in instrumental activity were consistently larger than observed under placebo conditions. The decreases in contingent activity were similar to those seen under placebo conditions. Smoking active marijuana was thus observed to produce increments in instrumental activity under motivational conditions involving contingencies for "work activities."

Adult↗

PubMed1994

Effects of social context, reinforcer probability, and reinforcer magnitude on humans' choices to compete or not to compete.

In the first two experiments, subjects' choices to earn points (exchangeable for money) either by competing with a fictitious opponent or by not competing were studied. Buskist, Barry, Morgan, and Rossi's (1984) competitive fixed-interval schedule was modified to include a second response option, a noncompetitive fixed-interval schedule. After choosing to enter either option, the opportunity for reinforcers became available after the fixed-interval's duration had elapsed. Under the no-competition condition, points were always available after the interval had elapsed. Under the competition condition, points were available based on a predetermined probability of delivery. Experiments 1 and 2 examined how reinforcer probabilities and reinforcer magnitudes affected subjects' choices to compete. Several general conclusions can be made about the results: (a) Strong preferences to compete were observed at high and moderate reinforcer probabilities; (b) competing was observed even at very low reinforcer probabilities; (c) response rates were always higher in the competition component than in the no-competition component; and (d) response rates and choices to compete were insensitive to reinforcer-magnitude manipulations. In Experiment 3, the social context of this choice schedule was removed to determine whether the high levels of competing observed in the first two experiments were due to a response preference engendered by the social context provided by the experimenters through instructions. In contrast to the first two experiments, these subjects preferred the 60-s fixed-interval schedule (formerly the no-competition option), indicating that the instructions themselves were responsible for the preference to compete. This choice paradigm may be useful to future researchers interested in the effects of other independent variables (e.g., drugs, social context, instructions) on competitive behavior.

Adult↗

PubMed1995

Human symbolic matching-to-sample performance: Effects of reinforcer and sample-stimulus probabilities.

Four experiments, each with 6 human subjects, varied the distribution of reinforcers for correct responses and the probability of sample-stimulus presentation in symbolic matching-to-sample procedures. Experiment 1 held the sample-stimulus probability constant and varied the ratio of reinforcers obtained for correct responses on the two alternatives across conditions. There was a positive relation between measures of response bias and the ratio of reinforcers. Experiment 2 held the ratio of reinforcers constant and varied the sample-stimulus probability across conditions. Unlike previous studies that used pigeons as subjects, there was a negative relation between bias and the ratio of sample-stimulus presentations. In Experiment 3, the sample-stimulus probability and the reinforcer ratio covaried across conditions. Response bias did not vary systematically across conditions. In Experiments 1 to 3, correct responses were reinforced intermittently. Experiment 4 used the same procedure as Experiment 3, but all correct responses now produced some scheduled consequence. There was a positive relation between response bias and the ratio of reinforcers. The results suggest that human performance in these tasks was controlled by both the relative frequency of reinforced responses and the relative frequency of nonreinforced responses.

Journal Article↗

PubMed1997

Key-peck probability and topography in a concurrent variable-interval variable-interval schedule with food and water reinforcers.

The relation between variables that modulate the probability and the topography of key pecks was examined using a concurrent variable-interval variable-interval schedule with food and water reinforcers. Measures of response probability (response rates, time allocation) and topography (peck duration, gape amplitude) were obtained in 5 water- and food-deprived pigeons. Key color signaled reinforcer type. During baseline, response rates and time allocations were greater to the food key than to the water key, and food-key pecks had larger gapes and shorter durations. Relative probability measures (for the food key) were increased by prewatering and decreased by prefeeding. Deprivation effects upon topography measures were apparent only when food- and water-key pecks were analyzed separately. Food-key gape amplitudes increased with prewatering and decreased with prefeeding. The clearest effect occurred with prewatering. There were no consistent effects upon water-key gapes. The key color-reinforcer relation was reversed for 3 pigeons to determine how response topography was modulated during the transition from food- to water-key pecks. Reacquisition was faster for the probability than for the topography measures. Analysis of gape-amplitude distributions during reversal indicated that response-form modulation proceeded through the generation of intermediate gape sizes.

Animals↗

PubMed2006

Use of a multivariable model to estimate the probability of discharge in hospitalized foals that are 7 days of age or less.

OBJECTIVE: To create a mathematical model to assist in early prediction of the probability of discharge in hospitalized foals < or= 7 days old. STUDY DESIGN: Prospective study. ANIMALS: 1,073 foals. PROCEDURES: Medical records from 910 hospitalized foals < or = 7 days old for which outcome was recorded as died or discharged alive were reviewed. Thirty-four variables including historical information, physical examination findings, and laboratory results were examined for association with survival. Variables associated with being discharged alive were entered into a multivariable logistic regression model. Accuracy of the model was validated prospectively on data from 163 foals. RESULTS: Factors in the final model included age group, ability to stand, presence of a suckle reflex, WBC count, serum creatinine concentration, and anion gap. Sensitivity and specificity of the model to predict live discharge were 92% and 74%, respectively, in the retrospective population and 90% and 46%, respectively, in the prospective population. Accuracy of an equine clinician's initial prediction of the foal being discharged alive was 83%, and accuracy of the model's prediction was 81%. Combining the clinician's prediction of probability of live discharge with that of the model significantly increased (median increase, 12%) the accuracy of the prediction for foals that were discharged and nonsignificantly decreased (median decrease, 9%) the accuracy of the predication for nonsurvivors. CONCLUSIONS AND CLINICAL RELEVANCE: Combining the clinician's initial predication of the probability of a foal being discharged alive with that of the model appeared to provide a more precise early estimate of the probability of live discharge for hospitalized foals.

Age Factors↗

PubMed1990

Directed attention influences the modification of startle reflex probability.

The present study was designed to investigate the effect of directed attention on elicitation and modification of the startle reflex. 30 adult human subjects received 90 dB(A) broadband noise startle stimuli either alone or preceded by a 60 dB(A) prepulse (either 2000-Hz tone, 1000-Hz tone, or broadband noise). Subjects were instructed to attend to one of the three prepulses during half the trials and to ignore all stimuli during the rest of the trials. The probability of responding while attending to a prepulse was significantly lower than the probability of responding while ignoring the prepulses. Responding to the prepulses was also more probable while subjects were attending to the prepulses, and these effects were more pronounced for tone than for noise prepulses. These results suggest that directed attention can influence the probability of the startle reflex without influencing startle amplitude or latency.

Adolescent↗

PubMed2004

Effects of milk urea nitrogen and other factors on probability of conception of dairy cows.

The objective of this study was to evaluate the relationships between milk urea nitrogen (MUN) and other factors and the probability of conception in dairy cows. Data were retrieved from the Lancaster Dairy Herd Improvement Association (DHIA). A total of 713 dairy herds and 10,271 dairy cows were included in the study. Logistic regression was used to determine the within-herd effects of MUN, milk production, lactation number, and breeding season on the probability of conception for each of 3 services. Within herds, MUN displayed a slight negative association with probability of conception at first service. For example, there was a 2- to 4-percentage unit decrease in conception rate at first service with a 10-mg/dL increase in MUN. In among-herd regression analysis, there was no effect of MUN on probability of conception. These results suggest that MUN may be related to conditions affecting reproduction of individual cows within a herd. Diet formulation usually would affect MUN equally among all cows at a similar stage of lactation in a herd. Because there was no effect of MUN among herds, diet formulation did not appear to affect conception rate.

Animals↗

PubMed2002

The probability of specific diagnoses for patients presenting with common symptoms to Dutch family physicians.

OBJECTIVE: Our goal was to develop reliable data on the probability of specific diagnoses among patients of family physicians (FPs) presenting with common symptoms. STUDY DESIGN: A group of 54 Dutch FPs recorded the reasons for encounter, diagnoses, and interventions for all episodes of care between 1985 and 1995. Diagnoses could be modified during the episode of care, and a modified diagnosis was applied to all episode data. POPULATION: We used the listed patient populations of the 54 Dutch FPs, representing 93,297 patient years, 236,027 episodes of care, and 267,897 patient encounters. OUTCOMES MEASURED: The top 20 diagnoses related to 4 selected presenting symptoms (cough, shortness of breath, general weakness/tiredness, and low back symptom/complaints without radiation), per 100 patients, with 95% confidence intervals, stratified by age. In the standard tables, age-specific cells with fewer than 10 observations were excluded. RESULTS: The availability of an accurate estimate of prior (pretest) probabilities for common symptoms/complaints has great potential value for family practice as an academic discipline and for family physicians in that it can support their medical decision making. Stratifying data by age groups increases the clinical relevance of the prior probabilities. CONCLUSIONS: Though collected by Dutch FPs, the data in our study have a high face validity for other clinicians. Still, FPs in other countries should give priority to collecting their own probability databases.

Adolescent↗

PubMed2000

Probabilities of Developing Cancer over the Whole Life Span of a Japanese.

To obtain a relevant index of the impact of cancer on the Japanese population, considering curable cases as well as mortalities, the probability of developing cancer in the entire life span of a Japanese was estimated. A method based on the cumulative risk of cancer was employed to estimate the probability. This cumulative risk method gave a lifetime probability of developing cancer in any site of 52 % for males and 31 % for females in 1994 up to 85+ years of age. and for the average life expectancy of Japanese, 77 years for males and 84 years for females, 32 % and 26 % respectively. The estimated probabilities provide reasonable and practical indices of the impact of cancer today. This method can be also applied to local estimation if population-based cancer registry data are available.

Journal Article↗

PubMed2004

[Value of the association of D-dimer measurement and the evaluation of clinical probability in a non-invasive diagnostic strategy of pulmonary embolism].

New diagnostic tools in suspected pulmonary embolism complete the classical diagnostic strategy of pulmonary scintigraphy and pulmonary angiography to limit the indications of these two invasive investigations. In a prospective series of 204 consecutive patients with suspected pulmonary embolism the association of D-dimer measurement and clinical probability was assessed for the exclusion of the diagnosis of pulmonary embolism. The D-DI Liatest is a new generation, unitary, rapid and quantitative latex test with a comparative diagnostic performance to that of the reference ELISA test, and well adapted to emergency situations.The clinical probability was assessed by a quantitative score based on past history, clinical symptoms and signs. The positive diagnosis of pulmonary embolism was made by spiral CT scanner and/or pulmonary angiography, associated with Duplex ultrasonography of the leg veins in nondiagnostic results. The prevalence of pulmonary embolism was 42.6% and the absence of anticoagulation in patients considered not to have pulmonary embolism was associated with a thrombo-embolic incidence of 0.9% at 3 months. Fifty-six patients had D-dimer concentrations equal or inferior to the threshold of 500 microg/L; the sensitivity was 99% and the specificity 47% with a negative predictive value of 98% to 100% in cases with a low clinical probability. D-dimer measurement is reliable and has a high cost-benefit value in ambulatory patients with suspected of pulmonary embolism and is even more valuable when the clinical probability of this diagnosis is low.

Female↗