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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 271 records · Page 15Linked to original sources
PubMed1993

Effects of delayed processing on mammographic phantom object detection.

OBJECTIVES: Delayed processing of films is a common occurrence in mobile mammography screening programs. The effects of such delayed processing on radiologists' detection of phantom test objects are investigated. METHODS: Twelve screen-film combinations were exposed using a phantom and developed after delays of 0, 1, 2, 3, 5, and 7 days. Films were scored by three board-certified radiologists specializing in mammography, based on visibility of calcifications, masses, fibrils, and line pairs. RESULTS: Variance analyses of mean scores indicate that, across screen-film combinations, there are no statistically significant decreases in object detection associated with delayed processing. The analyses do indicate, however, a statistically significant difference in scores unrelated to delay, attributable to the screen-film combination used. CONCLUSIONS: Delayed processing of mammography film does not lead to a decrease in the visibility of phantom test objects, despite large decreases in overall image optical density.

Analysis of Variance↗
PubMed1993

The significance of a positive flow cytometry crossmatch test in primary kidney transplantation.

This study was conducted to determine the efficacy of the T cell flow cytometry crossmatch (T-FCXM) test in 841 first cadaver donor transplants. Results showed one-year graft survival rates were 82% for T-FCXM-negative patients, compared with 75% for T-FCXM-positive patients (P = 0.01). Early one-month graft failure was 13 percentage points higher in those with a positive T-FCXM than those with a negative T-FCXM. The positive crossmatch patients also had more frequent immunological failures. A positive T-FCXM was found in 39% of the sensitized patients (PRA > 10%) and 8% of those who had not been sensitized. Patients with a positive T-FCXM in either category had a 74% graft survival rate. Thus, most of the T-FCXM-positive results occurred in patients with complement-fixing antibodies. It is suggested that flow cytometry crossmatching (FCXM) be used prospectively, despite the fact that many patients with a positive crossmatch did have successful transplants (TXs). In the current climate of a cadaver kidney scarcity and large recipient waiting pools, utilization of kidneys for patients with the highest probability of success seems a most prudent policy.

Antibodies↗
PubMed1993

Suicide among forensic psychiatric patients.

This paper examines the problem of suicide among patients discharged from a Regional Secure Unit. The stereotype that emerges is a young man with anti-social personality traits, suffering from an affective psychosis, with a history of substance abuse and impulsive violence directed both towards himself and others, who is alienated from care staff and social supports because of his provocative and uncooperative behaviour. In contrast with the general population, forensic patients are more likely to commit suicide using a violent method and are more likely to have a suicide verdict recorded by the coroner. The implications of these findings for treatment and preventive interventions are discussed.

Adult↗
PubMed1993

Conditional discrimination and equivalence relations: Control by negative stimuli.

Three adult subjects were taught the following two-sample, two-comparison conditional discriminations (each sample is shown with its positive and negative comparison, in that order): A1-B1B2, A2-B2B1; B1-C1C2, B2-C2C1; and C1-D1D2, C2-D2D1. A teaching procedure was designed to encourage control by negative comparisons. Subjects were then tested for emergent performances that would indicate whether the baseline conditional discriminations were reflexive, symmetric, and transitive. The tests documented the emergence of two classes of equivalent stimuli: A1, B2, C1, D2 and A2, B1, C2, D1. These were the classes to be expected if the negative comparisons were the controlling comparisons in the baseline conditional discriminations. The negative comparisons, however, were not the comparisons that subjects were recorded as having chosen in the baseline conditional discriminations. Differential test results confirmed predictions arising from a stimulus-control analysis: In reflexivity tests (AA, BB, CC, DD), subjects chose comparisons that differed from the sample; one-node transitivity (AC, BD) and "equivalence" (CA, DB) tests also yielded results that were the opposite of those to be expected from control by positive comparisons; symmetry tests (BA, CB, DC), two-node transitivity (AD) tests, and two-node "equivalence" (DA) tests yielded results that were to be expected from control by either positive or negative comparisons.

Journal Article↗
PubMed1993

High-density lipoprotein cholesterol and alcohol consumption in US white and black adults: data from NHANES II.

OBJECTIVES: High-density lipoprotein (HDL) cholesterol is known to be positively related to moderate alcohol consumption from studies in selected populations. This study describes the association in a representative sample of the US adult population. METHODS: Stratification and multivariate regression analyses were used to examine HDL cholesterol levels and alcohol consumption. RESULTS: Fewer women than men reported consumption of alcohol at any frequency. Similar percentages of Whites and Blacks reported alcohol consumption. Age-adjusted mean HDL cholesterol levels were higher among alcohol drinkers than among nondrinkers in all sex-race strata. Mean HDL cholesterol levels of Whites and Blacks of both sexes increased consistently with increased frequency of consumption of beer, wine, and liquor. With age, education, body mass index, smoking, and physical activity controlled for, there were higher age-adjusted HDL cholesterol levels with increasing reported quantities of alcohol consumed. Daily or weekly use of alcohol led to an increase of 5.1 mg/dL in mean HDL cholesterol level, whereas consumption of 1 g of alcohol led to an increase of 0.87 mg/dL. CONCLUSION: Even if there is a causal association between alcohol consumption and higher HDL cholesterol levels, it is suggested that efforts to reduce coronary heart disease risks concentrate on the cessation of smoking and weight control.

Adult↗
PubMed1993

Prevalence of diagnosed diabetes and selected related conditions of six reservations in Montana and Wyoming.

OBJECTIVE: To describe the prevalence of diabetes and related complications in Plains Indians. RESEARCH DESIGN AND METHODS: The medical records of individuals with diagnosed diabetes seen in IHS facilities before 1 January 1987 were reviewed. Records were obtained from primary care clinics and hospitals accessible to the following six reservation communities in Montana and Wyoming: Blackfeet, Crow, Fort Belknap, Fort Peck, Northern Cheyenne, and Wind River. Medical records were reviewed to ascertain accuracy of diagnosis and associated complications. RESULTS: Age-adjusted prevalence rate of diagnosed diabetes was 119/1000 adults > or = 15 yr of age. CONCLUSIONS: Diabetes rates in Plains Indians are higher than rates described for the general U.S. population.

Amputation, Surgical↗
PubMed1993

Handedness and accidents with injury.

As evidence for the hypothesis on the claim of reduced longevity for left-handers, Coren in 1989 reported data which suggested that left-handers were 1.89 times more likely to report injuries which required medical attention. This left-handed group included both left- and mixed-handed individuals. To clarify the results of his study, we repeated in part Coren's study but defined handedness so that groups of right-, mixed-, and left-handed individuals were considered. In contrast to Coren's data, we found that right- and left-handers did not differ significantly in the frequency with which they reported having experienced accidents with injury and that mixed-handers reported being significantly more likely to have had an injury-accident than either right- or left-handers. These data underscore the need to consider mixed-handedness as a separate group in studies of this type.

Accident Proneness↗
PubMed1993

Serum lipids of adults 20-74 years: United States, 1976-80.

This report presents descriptive and analytic data for serum total cholesterol, cholesterol lipoproteins, and triglycerides for adults 20-74 years of age by age, sex, and selected subgroups of the population at risk of developing coronary heart disease. This information is from the second National Health and Nutrition Examination Survey, which was conducted during the years 1976-80.

Adult↗
PubMed1993

Fiberoptic intubation prevents a tracheostomy in a trauma victim.

A 36-year-old male presented with knife-inflicted neck trauma. He was intubated in the emergency department but subsequently experienced an unplanned extubation. Multiple attempts at reintubation were unsuccessful with cricothyrotomy providing lifesaving. The patient was then fiberoptically intubated under controlled conditions sparing the victim from what otherwise would probably have been a tracheostomy.

Adult↗
PubMed1993

Effect of blood transfusion on serum iron and transferrin saturation.

The effect of transfusion of packed red blood cells on serum iron level, total iron-binding capacity, and transferrin saturation was studied. Samples of blood from 37 hemodynamically stable patients were obtained for analysis at various intervals following the transfusion of packed red blood cells. In 10 patients with possible iron deficiency, a significant rise in serum iron level and transferrin saturation occurred during the 24 hours following transfusion, which persisted at a marginally significant level up to 36 hours. In the remaining 27 patients, a significant rise was also noted in serum iron level and transferrin saturation results, but the rise did not persist beyond the 24 hours after transfusion. No change in total iron-binding capacity was noted in either group. These data show that the diagnosis of iron deficiency (based on a transferrin saturation of < 0.16) might be missed if iron studies are performed on patients within 24 hours following packed red blood cell transfusion. Therefore, if serum iron studies are obtained for patients suspected of having iron deficiency anemia, these studies are best done on blood samples obtained before blood transfusion.

Blood Transfusion↗
PubMed1992

1-(2-Aminoethyl)-3-methyl-8,9-dihydropyrano[3,2-e]indole: a rotationally restricted phenolic analog of the neurotransmitter serotonin and agonist selective for serotonin (5-HT2-type) receptors.

A series of rotationally restricted phenolic analogs of the neurotransmitter serotonin has been synthesized with the 5-hydroxyindole portion of serotonin replaced by a dihydropyrano[3,2-e]-indole (1, 3, 4, and 5) and a dihydropyrano[2,3-f]indole (2). The receptor binding profile of these compounds has been studied and compared to the natural substrate serotonin. The dihydropyrano[3,2-e]indole derivatives (1, 3, 4, and 5) possess lower affinity for 5-HT1 receptors but equal or greater affinity for 5-HT2 receptors. Like serotonin, these compounds dose-dependently stimulated phosphatidylinositol turnover in rat brain slices. Moreover, the response to 1-(2-aminoethyl)-3-methyl-8,9-dihydropyrano[3,2-]indole (5, CP-132,484) and 1-(2-aminoethyl)-8,9-dihydropyrano[3,2-e]indole (4) is selectively antagonized by 5-HT2 receptor antagonists establishing these tryptamines as selective 5-HT2 receptor agonists. The high affinity and potency of 5 for 5-HT2 receptors suggests that the C5-hydroxy group in serotonin can function as a hydrogen bond acceptor in a 5-HT2 receptor with a directionality of interaction which is down and away from C6 in serotonin (Figure 5). Furthermore, the potent affinity of these compounds for 5-HT2 receptors coupled with their poor affinity for 5-HT1 receptors indicates that the aminoethyl side chain of serotonin adopts significantly different conformations in 5-HT1 versus 5-HT2 receptors.

Animals↗