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Biomedical subjects

C Johnson

Publications and source records attributed to C Johnson.

At least 91 records · Page 5Linked to original sources
PubMed2000

Use of clindamycin disks To detect macrolide resistance mediated by ermB and mefE in Streptococcus pneumoniae isolates from adults and children.

We studied 198 macrolide-resistant S. pneumoniae isolates obtained from adults and children to evaluate whether 2-microgram clindamycin disks can distinguish between isolates manifesting ermB- versus mefE-mediated resistance to clarithromycin and to determine the relative frequency with which each resistance mechanism occurred in these populations. The mefE gene was predominant among 109 isolates from children, occurring in 73.4% versus 50.6% of 89 isolates from adults. Three isolates (1.5%) did not amplify either gene. Among 125 mefE(+) isolates, the MIC of clarithromycin at which 90% of the isolates tested were inhibited, determined by Etest, was 32 microgram/ml versus >256 microgram/ml in 70 ermB(+) isolates. All ermB(+) isolates were highly resistant to clindamycin (MICs >256 microgram/ml), whereas all mefE(+) isolates were susceptible to clindamycin using the 2-microgram disk. Testing S. pneumoniae from the respiratory tract for susceptibility to clindamycin by agar disk diffusion is an easy and inexpensive method to estimate the frequency of resistance mediated by ermB in specific patient populations. Macrolide resistance mediated by ermB is usually of greater magnitude than that due to mefE. Clinical studies are needed to determine the significance of high- versus low-level macrolide resistance in S. pneumoniae.

Adult↗
PubMed2000

Reduced concentrations of thalamic N-acetylaspartate in male patients with schizophrenia.

OBJECTIVE: The authors measured N-acetylaspartate (a putative neuronal marker) in the right and left thalamus of 17 male patients with schizophrenia using in vivo proton magnetic resonance spectroscopic imaging ((1)H MRSI). METHOD: (1)H MRSI was performed on 17 medicated male patients with schizophrenia and 10 male comparison subjects. Concentrations of N-acetylaspartate, creatine, and choline were determined in the thalamic regions bilaterally. RESULTS: The patients with schizophrenia demonstrated significantly lower concentrations of N-acetylaspartate than the comparison subjects in both the right and left thalamic regions. Right thalamic N-acetylaspartate and left thalamic N-acetylaspartate were significantly correlated in the patients but not in the comparison subjects. There was no association between N-acetylaspartate and duration of illness or medication dose. No group differences or lateralized asymmetries in choline or creatine were noted. CONCLUSIONS: The finding of reduced concentrations of N-acetylaspartate bilaterally suggests neuronal dysfunction and/or loss in both the right and left thalamic regions in male patients with schizophrenia.

Adult↗
PubMed2000

Sustained swimming at low velocity following a bout of exhaustive exercise enhances metabolic recovery in rainbow trout.

Sustained swimming at 0.9 BL s(-)(1), where BL is fork body length, following a bout of exhaustive exercise enhanced recovery of metabolite and acid-base status in rainbow trout compared with fish held in still water. The most striking effect of an active recovery was a total absence of the elevation cortisol concentration typically associated with exhaustive exercise. In fish swimming at 0. 9 BL s(-)(1), plasma cortisol levels averaged 20-25 ng ml(-)(1) throughout the 6 h recovery period. In contrast, plasma cortisol increased to a peak level of 128.4+/-11.2 ng ml(-)(1) (mean +/- s.e. m., N=6) in fish recovering in still water. Muscle glycogen was completely resynthesized and lactate cleared within 2 h of exercise in swimming fish compared with more than 6 h required in the fish held in still water. Similarly, blood lactate level and acid-base status were restored more quickly in the swimming fish. These observations suggest that the prolonged recovery usually associated with exhaustive exercise in rainbow trout is due to elevations in plasma cortisol concentration and that the stimulus for cortisol release is not exercise per se, but rather post-exercise inactivity.

Acid-Base Equilibrium↗
PubMed2000

Social categorization and stereotyping: 'You mean I'm one of "them"?'.

What happens when people discover that they are members of a group about which they have previously formed some stereotype? To address this question, procedures previously shown to induce negative stereotypes of minority groups were combined with a social categorization manipulation. Participants in a distinctiveness-based illusory correlation paradigm (Hamilton & Gifford, 1976) either knew nothing about their group membership, or learned that they were a member of the minority group or the majority group either before or after being presented the stereotype-engendering stimulus materials. Results revealed that social categorization into the minority group before stimulus presentation eliminated the perceived stereotype and reversed the evaluative bias, whereas social categorization into the minority group after stimulus presentation had no effect on the perceived stereotype and only a weak effect in reducing the evaluative bias. Social categorization into the majority group either before or after stimulus presentation had little effect on the perceived stereotype and evaluative bias. These results clarify the process underlying the influence of social categorization on stereotype formation, underscore the distinction between affective and cognitive influences on stereotype formation and stereotype change, and offer insights into 'autostereotyping' among members of minority groups.

Humans↗
PubMed2000

Proton magnetic resonance spectroscopy of the human brain in schizophrenia.

In vivo proton magnetic resonance spectroscopy (1H MRS) has been utilized by neuroimaging laboratories in recent years to reliably measure compounds such as N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and to a lesser extent glutamate and glutamine in the human brain. To date, the most consistently replicated findings in schizophrenia are reduced NAA measures in the hippocampal regions. Since NAA is thought to be a neuronal/axonal marker and a measure of neuronal/axonal integrity, hippocampal NAA reductions have been interpreted as strong evidence for neuronal/axonal loss or dysfunction in this brain region. The evidence for neuronal loss or dysfunction based on NAA is less consistent for the frontal cortex and white matter, temporal cortex, basal ganglia, cingulate region, and thalamus in schizophrenia. Furthermore, there are no consistently replicated findings for choline or creatine alterations in any of the brain regions examined in schizophrenia. Finally, significant technical difficulties make reliable measurement of glutamine and glutamate problematic at the present time.

Aspartic Acid↗
PubMed2000

Older adults and financial bequests.

Using data from Aging and Health Dynamics (AHEAD), this research investigated a model predicting an older adult's assessment regarding the chances (from 0 to 100) of leaving a financial bequest. Structural equation modeling analyses revealed three significant predictors of a high assessment (i.e., older age, high sense of control, and high socioeconomic status) and three predictors of a low assessment (i.e., race, physical health problems, and assessment of the chances of medical expenses depleting savings). Whites had higher financial bequests assessments than non-Whites. Physical health problems and the depleting savings assessment exerted negative effects on the financial bequest assessment. Marital status and negative psychological functioning exerted indirect effects through sense of control and through the depleting savings assessment.

Activities of Daily Living↗
PubMed2000

The effects of medical group practice and physician payment methods on costs of care.

OBJECTIVE: To assess the effects of payment methods on the costs of care in medical group practices. DATA SOURCES: Eighty-six clinics providing services for a Blue Cross managed care program during 1995. The clinics were analyzed to determine the relationship between payment methods and cost of care. Cost and patient data were obtained from Blue Cross records, and medical group practice clinic data were obtained by a survey of those organizations. STUDY DESIGN: The effects of clinic and physician payment methods on per member per year (PMPY) adjusted patient costs are evaluated using a two-stage regression model. Patient costs are adjusted for differences in payment schedules; patient age, gender, and ACG; clinic organizational variables are included as explanatory variables. DATA COLLECTION: Patient cost data were extracted from Blue Cross claims files, and patient and physician data from their enrollee and provider data banks. Medical group practice data were obtained by a mailed survey with telephone follow-up. PRINCIPAL FINDINGS: Capitation payment is correlated with lower patient care costs. When combined with fee-for-service with withhold provisions, this effect is smaller indicating that these two clinic payment methods are not interchangeable. Clinics with more physician compensation based on measures of resource use or based on some share of the net revenue of the clinic have lower patient care costs than those with more compensation related to productivity or based on salary. Salary compensation is strongly associated with higher costs. The use of physician profiles and clinical guidelines is associated with lower costs, but referral management systems have no such effect. The lower cost clinics are the smaller, multispecialty clinics. CONCLUSIONS: This study indicates that payment methods at both the medical group practice and physician levels influence the cost of care. However, the methods by which that influence is manifest is not clear. Although the organizational structure of clinics and their use of managed care programs appear to play a role, this influence is less than expected.

Adolescent↗
PubMed2000

Pathways to wellness.

The data you collect is one thing. The way you look at it is far more important. The Wellness Councils of America reports on an innovative program in a state where bad health behaviors abound.

Data Collection↗
PubMed2000

Frequency doubling perimetry and the detection of eye disease in the community.

PURPOSE: Frequency Doubling Technology (FDT) perimetry is a novel perimetric test that provides rapid screening (45 to 60 seconds) and full-threshold (4 to 5 minutes) testing for detection of vision loss. The purpose of this study was to determine the specificity and sensitivity of FDT perimetry for the detection of ocular disease. METHODS: A total of 130 participants (257 eyes of 42 men and 88 women) recruited from the community completed FDT perimetry, standard achromatic automated perimetry (SAP), anterior segment biomicroscopy, tonometry, and dilated ophthalmoscopy. FDT results were considered abnormal if 1 point was abnormal (depressed below the 5% level on the screening protocol C-20-5). SAP was considered abnormal if the glaucoma hemifield test or pattern standard deviation was outside normal limits (P < .05) or a hemifield cluster of 3 depressed points on the pattern deviation probability plot (P < .05) was present. An abnormal eye examination was defined as the presence of an abnormality in the anterior segment, lens, or posterior segment that was likely to cause a visual field defect or the presence of glaucomatous or other optic neuropathy. RESULTS: The mean age (+/- SD) of participants was 55.5 years (+/- 10.3). Ethnic groups, as reported by participants, included 77 (59%) African Americans, 40 (31%) Caucasians, and 13 (10%) in other groups. On clinical examination, 116 eyes (45%) were normal, 9 eyes (3.5%) had a cataract with best corrected visual acuity worse than 20/30, 16 eyes (6%) had open-angle glaucoma, and 17 eyes (7%) had retinal findings or lesions that were likely to cause a visual field defect. For FDT perimetry, 22 (8.6%) of 257 tests were unreliable, and for SAP, 65 (25.3%) of 257 tests were unreliable. The sensitivity and specificity of FDT perimetry for detecting an abnormal clinical examination were 55% and 90% and for detecting an abnormal examination that included an abnormal SAP, 64% and 86%. CONCLUSIONS: FDP demonstrated reasonable discriminatory power for detecting eye disease.

Adult↗
PubMed2000

We made a mistake.

When Annals of Internal Medicine published a paper about the risk-management program at Veterans Affairs Medical Center, Lexington, Ky., readers were surprised at the facility's open policy regarding medication errors. Here's how health care leaders there put their liability on the line for better patient care.

Attitude of Health Personnel↗
PubMed1999

An N-terminal nuclear export signal is required for the nucleocytoplasmic shuttling of IkappaBalpha.

The potent transcriptional activities of Rel/NF-kappaB proteins are regulated in the cytoplasm and nucleus by the inhibitor, IkappaBalpha. The mechanism, by which IkappaBalpha can either sequester NF-kappaB in the cytoplasm or act as a nuclear post-induction repressor of NF-kappaB, is uncertain. We find that IkappaBalpha shuttles continuously between the nucleus and cytoplasm. This shuttling requires a previously unidentified CRM1-dependent nuclear export signal (NES) located within the N-terminal domain of IkappaBalpha at amino acids 45-55. Deletion or mutation of the N-terminal NES results in nuclear localization of IkappaBalpha. NF-kappaB (p65) association with IkappaBalpha affects steady-state localization but does not inhibit its shuttling. Endogenous complexes of IkappaBalpha-NF-kappaB shuttle and will accumulate in the nucleus when CRM1 export is blocked. We find TNFalpha can activate the nuclear IkappaBalpha-NF-kappaB complexes by the classical mechanism of proteasome-mediated degradation of IkappaBalpha. These studies reveal a more dynamic nucleocytoplasmic distribution for IkappaBalpha and NF-kappaB suggesting previously unknown strategies for regulating this ubiquitous family of transcription activators.

3T3 Cells↗
PubMed1999

Use of the selective oral neuraminidase inhibitor oseltamivir to prevent influenza.

BACKGROUND: Safe and effective antiviral agents are needed to prevent infection with influenza A and B virus. Oseltamivir (GS4104), which can be administered orally, is the prodrug of GS4071, a potent and selective inhibitor of influenzavirus neuraminidases. We studied the use of oseltamivir for long-term prophylaxis against influenza in two placebo-controlled, double-blind trials at different U.S. sites during the winter of 1997-1998. METHODS: We randomly assigned 1559 healthy, nonimmunized adults 18 to 65 years old to receive either oral oseltamivir (75 mg given once or twice daily, for a total daily dose of 75 or 150 mg) or placebo for six weeks during a peak period of local influenzavirus activity. The primary end point with respect to efficacy was laboratory-confirmed influenza-like illness (defined as a temperature of at least 37.2 degrees C accompanied by at least one respiratory and at least one systemic symptom). RESULTS: In the two studies combined, the risk of influenza among subjects assigned to either once-daily or twice-daily oseltamivir (1.2 percent and 1.3 percent, respectively) was lower than that among subjects assigned to placebo (4.8 percent; P<0.001 and P=0.001 for the comparison with once-daily and twice-daily oseltamivir, respectively). The protective efficacy of oseltamivir in the two active-treatment groups combined was 74 percent (95 percent confidence interval, 53 to 88 percent) at all the sites combined and 82 percent (95 percent confidence interval, 60 to 93 percent) at sites in Virginia, where the rate of influenza infection was higher than the overall rate. For culture-proved influenza, the rate of protective efficacy in the two oseltamivir groups combined was 87 percent (95 percent confidence interval, 65 to 96 percent). The rate of laboratory-confirmed influenza infection was lower with oseltamivir than with placebo (5.3 percent vs. 10.6 percent, P<0.001). Oseltamivir was well tolerated but was associated with a greater frequency of nausea (12.1 percent and 14.6 percent in the once-daily and twice-daily groups, respectively) and vomiting (2.5 percent and 2.7 percent, respectively) than was placebo (nausea, 7.1 percent; vomiting, 0.8 percent). However, the frequency of premature discontinuation of drug or placebo was similar among the three groups (3.1 to 4.0 percent). CONCLUSIONS: Oseltamivir administered daily for six weeks by the oral route is safe and effective for the prevention of influenza.

Administration, Oral↗
PubMed1999

Clinical and economic assessment of the omeprazole test in patients with symptoms suggestive of gastroesophageal reflux disease.

OBJECTIVE: To evaluate the diagnostic accuracy of a trial of a high-dose proton pump inhibitor (the omeprazole test) in detecting gastroesophageal reflux disease (GERD) in patients with heartburn symptoms. DESIGN: A randomized, double-blind, placebo-controlled, crossover trial. PATIENTS AND SETTING: Forty-three consecutive patients with symptoms suggestive of GERD were enrolled at a Veterans Affairs medical center. MAIN OUTCOME MEASURES: Symptom response to the omeprazole test vs placebo in GERD-positive and GERD-negative patients; sensitivity, specificity, and positive and negative predictive values of the omeprazole test; and cost per correct diagnosis achieved with the omeprazole test compared with traditional diagnostic strategies. RESULTS: Of 42 patients (98%) who completed the study, 35 (83%) were classified as GERD positive and 7 (17%) as GERD negative. Twenty-eight GERD-positive and 3 GERD-negative patients responded to the omeprazole test, providing a sensitivity of 80.0% (95% confidence interval, 66.7%-93.3%) and a specificity of 57.1% (95% confidence interval, 20.5%-93.8%). Economic analysis revealed that the omeprazole test saves $348 per average patient evaluated, and results in a 64% reduction in the number of upper endoscopies performed and a 53% reduction in the use of pH testing. CONCLUSIONS: The omeprazole test is sensitive and fairly specific for diagnosing GERD in patients with typical GERD symptoms. This strategy could result in significant cost savings and decreased use of invasive diagnostic tests.

Adult↗
PubMed1999

Extraction and high-performance liquid chromatographic separation of selected pyrene and benzo[a]pyrene sulfates and glucuronides: preliminary application to the analysis of smokers' urine.

In the study of the complex mixture of urinary metabolites derived from polycyclic aromatic hydrocarbon compounds, it is desirable to simplify the analysis through separation of classes of compounds. We have developed a liquid chromatography (LC) method for the separation of selected sulfate and glucuronide conjugate isomers derived from hydroxybenzo[a]pyrenes (OH-BaP) and hydroxypyrenes. This LC method was utilized in the preliminary analysis of the urine of smokers by combining it with an extraction technique employing tetra-n-butyl-ammonium ion as a coupling agent to generate a 1:1 complex, extractable in chloroform at low pH prior to LC analysis.

Benzo(a)pyrene↗