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Biomedical subjects

R A Hanson

Publications and source records attributed to R A Hanson.

At least 19 recordsLinked to original sources
PubMed2004

Abducens length and vulnerability?

BACKGROUND: Several sources have attributed the vulnerability of the abducens nerve to its long intracranial course. However, other anatomic factors likely contribute to the apparent vulnerability of the abducens nerve to mass lesions and trauma. METHODS: The authors performed a two-part anatomic study of the abducens nerve. In the first part of the study, they compared the length of the abducens with another cranial nerve, the trochlear, at the autopsy of 26 pediatric patients. In the second part of the study, the authors used an endoscopic exposure of these two cranial nerves in a preserved human cadaver head. RESULTS: The abducens nerve was consistently approximately one-third the length of the trochlear nerve at all ages that they studied. The endoscopic views revealed the structural and vascular relationships of the abducens nerve in situ. CONCLUSIONS: The authors conclude from these findings and the literature that abducens nerve vulnerability results from factors other than its intracranial length.

Abducens Nerve↗
PubMed2004

Development of a standardized susceptibility test for campylobacter with quality-control ranges for ciprofloxacin, doxycycline, erythromycin, gentamicin, and meropenem.

A standardized agar dilution susceptibility testing method was developed for Campylobacter that consisted of testing on Mueller-Hinton medium supplemented with 5% defibrinated sheep blood in an atmosphere of 10% CO2, 5% O2, and 85% N2. Campylobacter jejuni ATCC 33560 was identified as a quality-control (QC) strain. Minimal inhibitory concentration (MIC) QC ranges were determined for two incubation time/temperature combinations: 36 degrees C for 48 hr and 42 degrees C for 24 hr. Quality-control ranges were determined for ciprofloxacin, doxycycline, erythromycin, gentamicin, and meropenem. For all antimicrobial agents tested at both temperatures, 95-100% of the QC MIC results fell within recommended QC ranges. Twenty-one Campylobacter clinical isolates, encompassing five species of Campylobacter (C. jejuni, C. coli, C. jejuni, subsp. doylei, C. fetus, and C. lari) were tested in conjunction with the C. jejuni QC strain. While C. jejuni and C. coli could be reliably tested under both test conditions, growth of C. jejuni subsp. doylei, C. fetus, and C. lari isolates was inconsistent when incubated at 42 degrees C. Therefore, it is recommended that these species only be tested at 36 degrees C.

Campylobacter↗
PubMed2000

Management of multiple sclerosis across managed care and fee-for-service systems.

OBJECTIVE: To measure and compare care for adults with MS across managed care and fee-for-service (FFS) health systems. METHODS: The authors sampled adults with MS having physician visits over a 2-year period from a group model health maintenance organization (HMO) in southern California, from a midwestern independent practice association (IPA) model managed care plan, and from the FFS portion of the practices of a random sample of southern California neurologists. The authors mailed surveys to subjects in mid-1996; 930 of 1,164 (80%) of those eligible responded. The authors measured sociodemographic and clinical characteristics, management of recent changes in mobility, bladder control, and fatigue, use of a disease-modifying agent, assessment of general health symptoms and issues, and unmet information needs. The authors adjusted comparisons between systems for comorbidity, disease severity, and disease type. RESULTS: The groups differed on most sociodemographic and clinical characteristics. There were few differences in symptom management; differences that did exist tended toward more referrals or treatment for the FFS group. Access to the disease-modifying agent available at the time of the survey did not differ across systems, although patients' perceptions of the rationale for not using the drug did vary. General health issues and symptoms were more often assessed in the FFS and IPA systems than in the HMO, but improvement was needed across all three systems of care. There were substantial unmet information needs in all groups and especially high ones in the FFS and HMO samples. CONCLUSIONS: Strategies to improve care for people with MS should be developed and evaluated, particularly in areas like symptom assessment and meeting patient information needs. Where variations in service delivery exist, longitudinal studies are also needed to evaluate the potential impact on outcomes and to evaluate reasons for variation.

Activities of Daily Living↗
PubMed1996

High-dose corticotropin (ACTH) versus prednisone for infantile spasms: a prospective, randomized, blinded study.

OBJECTIVE: To compare the efficacy of corticotropin (ACTH) (150 U/m2/day) and prednosone (2 mg/kg/day) given for 2 weeks, in suppressing clinical spasms and hypsarrhythmic electroencephalogram (EEG) in infantile spasms (IS). AACTH and prednisone are standard treatments for IS. ACTH at high doses causes severe dose- and duration-dependent side effects, but may be superior to prednisone, based on retrospective or uncontrolled studies. Blinded prospecive studies have shown equal efficacy of prednisone and low-dose ACTH, and low versus high-dose ACTH. DESIGN: A prospective, randomized, single-blinded study. SUBJECTS AND METHODS: Patient population consisted of consecutive infants fulfilling entry criteria, including the presence of clinical spasms, hypsarrhythmia (or variants) during a full sleep cycle video-EEG, and no prior steroid/ACTH treatment. Response required both cessation of spasms and elimination of hypsarrhythmia by the end of the 2-week treatment period, as determined by an investigator "blinded" to treatment. Treatment of responders was tapered off over 12 days; those failing one hormone were crossed-over to the other. RESULTS: OF 34 eligible infants, 29 were enrolled. Median age of patients was 6 months. Twenty-two infants were "symptomatic" with known or suspected cause, and seven were cryptogenic (two normal). Of 15 infants randomized to ACTH, 13 responded by EEG and clinical criteria (86.6%); Seizures stopped in an additional infant, but EEG remained hypsarrhythmic (considered a failure). Four of the 14 patients given prednisone responded (28.6%,, with complete clinical-EEG correlation), significantly less than with ACTH, (chi2 test). CONCLUSIONS: Using a prospective, randomized approach, a 2-week course of high-dose ACTH is superior to 2 weeks of prednsone for treatment of IS, as assessed by both clinical and EEG criteria.

Adrenocorticotropic Hormone↗
PubMed1995

Cerebrospinal fluid corticotropin and cortisol are reduced in infantile spasms.

Infantile spasms respond to ACTH, and levels of the hormone in cerebrospinal fluid of untreated infants with this disorder were found to be lower than in age-matched controls. In this study we analyzed cerebrospinal fluid cortisol and ACTH using improved immunoassays in a larger cohort of infants with infantile spasms. Analysis of 20 patients and 15 age-matched controls revealed significantly lower levels of both ACTH and cortisol in the cerebrospinal fluid. These data, combined with the efficacy of ACTH and glucocorticoids for infantile spasms, support an involvement of the brain-adrenal-axis in this disorder.

Adrenocorticotropic Hormone↗
PubMed1993

Quantitative assessment of human fetal renal blood flow.

OBJECTIVE: Our purpose was to longitudinally quantify human fetal renal blood flow. STUDY DESIGN: Twenty-two normal fetuses underwent a color-pulsed Doppler evaluation of the renal artery. The Doppler waveforms were digitized to assess the velocity-time integral. The size of the vessel was determined during systole with color high-resolution two-dimensional ultrasonography. Renal blood flow was estimated by multiplying the time-velocity integral (i.e., area under the curve) by the area of the renal artery. The combined cardiac output was calculated by adding right and left inflow Doppler-derived volumes. RESULTS: Renal artery size, peak flow velocity, time-velocity integral, and renal blood flow significantly increased with advancing gestational age. The resistivity indexes, such as the systolic/diastolic ratio or the Pourcelot index of the fetal renal artery, did not significantly change with advancing gestational age. The pulsatility index, however, was correlated with gestational age. The percentage of the combined cardiac output to the fetal kidney remained constant throughout gestation. CONCLUSIONS: Color pulsed Doppler can be used to visualize small and deep vascular structures in the human fetus. Renal blood flow increased with advancing gestational age. This increase seems to be related to the increase in the combined cardiac output.

Blood Flow Velocity↗
PubMed1990

Initial parenting attitudes of pregnant adolescents and a comparison with the decision about adoption.

The Adult-Adolescent Parenting Inventory was used to examine the initial parenting attitudes of a sample of pregnant adolescents. In addition, the attitudes about parenting were correlated with the decision of the adolescent to either keep or place the baby for adoption. Pregnant adolescents scored significantly lower on the "expectations for children" construct than all groups of controls. They scored significantly higher than adolescent controls on the "empathy" construct but lower than the adult controls. On the "corporal punishment" construct, they scored significantly lower than nonabused adolescent controls but were similar to abused adolescent controls. On the "role-reversal" construct, they scored significantly higher than abused adolescent controls, lower than adult controls, and about the same as nonabused adolescent controls. Adolescents who placed their babies had significantly lower scores on the role-reversal measure, but the differences between keepers and placers on the expectations, empathy, and corporal punishment dimensions were not significant. The results are discussed in terms of (1) the areas where attitudes about parenting are below appropriate levels, (2) the possibility of competent teenage mothers, and (3) the groundwork necessary for preparing adolescents for parenthood should they elect to keep their babies.

Adolescent↗
PubMed1983

Perspective-taking among offender and nonoffender youth.

Research has shown that adolescents show varying abilities in the area of social perspective-taking. The relative importance of offender and nonoffender status or sex on perspective-taking abilities is still unclear. The purpose of this paper was to investigate differences between male and female offender and nonoffender youth in this area. Subjects of the study were 117, 14- and 15-year-old adolescents, 64 boys and 53 girls from three juvenile facilities and one public high school in the midwest. Perspective-taking was assessed by having subjects take the Rest's Defining Issue Test (DIT) three consecutive times, as himself/herself, as a teacher, and as a police officer. Findings of the study indicated that 14- and 15-year-old offenders and non-offenders did not differ in their perspective-taking ability across three social roles. One explanation for this finding may be that younger adolescents are in developmental transition in this domain of cognitive functioning. Suggestions for future research in this area were made.

Adolescent↗