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Biomedical subjects

C E Johnson

Publications and source records attributed to C E Johnson.

At least 19 recordsLinked to original sources
PubMed2006

Using CT in the diagnosis and management of patients with cerebral vasospasm.

Cerebral vasospasm remains a serious complication of aneurysmal subarachnoid hemorrhage. Efforts in improving its clinical outcome have been focused on early diagnosis and applying effective treatment regimens. Standard diagnostic modalities currently used do not fully address this complex disease. The use of CT angiography and CT perfusion are discussed, with emphasis on its potential role in not only detecting vasospasm, but also in guiding management decisions and assessing clinical outcome.

Angiography↗
PubMed2003

Long term cryostorage of UC blood units: ability of the integral segment to confirm both identity and hematopoietic potential.

BACKGROUND: With the maturation of UC blood banking, cord blood (CB) units stored for years prior to use in transplantation present a new set of issues in clinical transplantation, including interval improvements in immune typing and confirmation of product identity and viability. A preliminary analysis of the transplants supported by the St Louis Cord Blood Bank, looking for an impact of length of CB storage time and transplant outcome was performed. We evaluated the utility of an integral segment containing an aliquot of cryopreserved product that has been exposed to the same post-processing storage conditions as the unit as a quality control tool for CB banking. METHODS: Engraftment and survival following unrelated donor UC blood transplant were evaluated based on length of CB product storage at the St Louis Cord Blood Bank. A strategy of routine testing of the contiguous segment for high-resolution HLA typing (also confirming identity) and CFU analysis was tested in 283 consecutive CB searches. Comparison between CB unit and contiguous segment viability and hematopoietic potential was performed on 30 research CB units that had been stored up to 5 years. RESULTS: There was no statistical difference in engraftment or survival following unrelated donor cord blood transplant employing units banked < 1 year or > 3 years. Confirmatory HLA typing, CFU and viability testing was successfully performed from the same segment as part of a strategy for product release evaluation. When comparing the segment with its corresponding CB unit, the total colony-forming units (CFU) measured in the two was similar (P = 0.51, paired t-test). Three research units purposely sabotaged by an overnight thaw and refreeze had no CFU growth, but viability as measured by Trypan was still 68-98%. DISCUSSION: No deterioration of hematopoietic potential has been detected with storage up to 5 years. The contiguous segment CFU is representative of the product, and thus is a useful tool for quality control and confirmation of product viability. Viability, as measured by Trypan blue dye exclusion may be falsely reassuring.

Blood↗
PubMed2001

Stability of norfloxacin in an extemporaneously prepared oral liquid.

The stability of norfloxacin in an extemporaneously prepared suspension stored at room temperature and under refrigeration was studied over 56 days. A 20-mg/mL suspension was prepared from commercially available 400-mg norfloxacin tablets and equal amounts of Ora-Plus and strawberry syrup to make a final volume of 60 mL. Six identical samples of the suspension were prepared in amber plastic prescription bottles. Three were stored at room temperature (23-25 degrees C) and three under refrigeration (3-5 degrees C). Immediately after preparation and at 7, 14, 28, and 56 days, the samples were assayed in duplicate by stability-indicating high performance liquid chromatography. The samples were also inspected for color and odor changes and the pH of each sample was determined. At least 93% of the initial norfloxacin concentration remained throughout the 56-day study period. The color, odor, and pH of all of the samples did not change appreciably. An extemporaneously prepared suspension of norfloxacin 20 mg/mL was stable for at least 56 days when stored at either 23-25 or 3-5 degrees C.

Anti-Infective Agents↗
PubMed2001

A simple and reliable procedure for cord blood banking, processing, and freezing: St Louis and Ohio Cord Blood Bank experiences.

BACKGROUND: In UC blood banking, volume and RBC reduction of the collected UC blood allows more efficient long-term storage and decreases infusion-related hemolysis and DMSO toxicity. However, high cell yields are imperative. At the St Louis Cord Blood Bank, we have systematically addressed processing/freezing and have developed a simple processing/freezing procedure. METHOD: The methodology is a modification of the hetastarch sedimentation and volume reduction approach of Rubinstein at the New York Placental Blood Program. Cord blood is mixed with a 1:5 v/v ratio of hetastarch. The product is incubated for 45 min in an inverted position in a refrigerated centrifuge (4 degrees C), and then is spun for 5 min at 50 g. RBC concentrate is drained from the bottom. The volume drained is calculated to remove 80% of RBC. The UC blood unit is then resuspended and spun for 13 min at 420 g. Plasma is expressed from the top. RESULTS: A final product volume of 27 mL (range 16-58 mL) was obtained from an original 50-200 mL of UC blood collected. The average yield of total nucleated cells pre- and post-processing was 90% for the first 4055 UC blood units banked. Pre- and post-processing CFU and CD34 yields were tested in a cohort and were similarly conserved. With a processing time of 3 h for a single cord, this process is time efficient and lends itself well to processing several units at the same time. The technique has been exported to other laboratories with similar yields. DISCUSSION: This simple methodology results in reliable yields and is well suited to larger scale banking.

Blood Banking↗
PubMed2001

Use of plasma exchange and heparin during cardiopulmonary bypass for a patient with heparin induced thrombocytopenia: a case report.

Patients with documented history of heparin-induced thrombocytopenia (HIT) pose a difficult problem during surgery using cardiopulmonary bypass (CPB). Several alternatives to heparin exist, but these products either are not approved for use in the United States or have more side effects than heparin. We report on a patient with documented heparin-induced antibody and left main coronary artery disease who underwent uneventful coronary artery bypass surgery and recovery by using preoperative plasmaphresis and limited use of porcine intestinal heparin during CPB.

Acute Disease↗
PubMed2001

The role of antibacterial therapy of acute otitis media in promoting drug resistance.

Treatment of acute otitis media (AOM) is the leading cause of antibacterial use in children in most developed countries. Rates of Streptococcus pneumoniae strains resistant to many classes of antibacterial agents have risen dramatically in many countries over the past 20 years. While more restricted use of antibacterial agents for AOM would almost certainly slow the rise in resistance, AOM is a potentially painful disease and may have suppurative complications such as mastoiditis. In this review, we discuss the prudent use of antibacterial agents for AOM and provide an overview of the epidemiology of S. pneumoniae resistance worldwide. Data from 10 placebo-controlled studies in patients with AOM show that antibacterial treatment is generally associated with a significantly higher cure rate than placebo. Of the three studies which analysed children <2 years of age, cure rates were 28 to 48% for placebo and 41 to 74% with antibacterial agents. Of the studies purporting to show no difference in cure rates between placebo and antibacterial therapy, the diagnostic criteria defining entry into the study were poor; therefore, the studies may have included many children without bacterial disease. Accurate diagnosis of AOM is the key element in reducing unnecessary antibacterial usage. Either pneumatic otoscopy or tympanometry can provide evidence of an effusion and the presence of an opaque, yellow or creamy white bulging eardrum will confirm AOM. Finally, the selection of appropriate antibacterial agents will reduce the rise in resistance. Low dosages of antibacterial agents used for prophylaxis select for resistance, and certain classes of drugs such as the sulfonamides and macrolides appear to do the same even at therapeutic doses. Amoxicillin at high dosages should remain the first-line antibacterial agent. In the future, use of vaccination strategies against pneumococci, influenza, respiratory syncytial virus and non-typeable Haemophilus influenzae will also decrease antibacterial use.

Acute Disease↗
PubMed2001

Subtendinous bone marrow edema patterns on MR images of the ankle: association with symptoms and tendinopathy.

OBJECTIVE: We sought to describe a pattern of subtendinous bone marrow edema on MR images of the ankle and to determine if there is an association with location of symptoms and overlying tendinopathy. MATERIALS AND METHODS: At 1.5 T, 141 MR examinations of the ankle (116 clinical examinations of patients with chronic pain, 25 of asymptomatic control patients) were performed using T1-weighted, proton density-weighted fast spin-echo, and T2-weighted fat-suppressed fast spin-echo sequences. Images were retrospectively reviewed by two musculoskeletal radiologists for presence of bone marrow edema occurring in a subcortical location associated with the course of the medial or lateral tendon groups, as well as focal thickening or increased T2 signal within the tendons. These findings were correlated with clinical information regarding symptom location. The association of subtendinous marrow edema with tendinopathy and symptom location was statistically analyzed. RESULTS: Subtendinous bone marrow edema was present at 26 sites on 24 ankle MR examinations (17%) (at the medial malleolus [n = 17] associated with the posterior tibialis tendon, at the lateral malleolus [n = 6] and the calcaneus [n = 2] associated with the peroneus longus and brevis tendons, and at the cuboid [n = 1] associated with the peroneus longus tendon). These subtendinous bone marrow edema patterns were significantly associated with overlying tendon abnormality medially (p = 0.001) and laterally (p = 0.001), and with symptoms medially (p = 0.0016) but not laterally (p = 0.078). CONCLUSION: On MR images of the ankle, bone marrow edema localized in a subtendinous location is associated with overlying tendinopathy medially and laterally and with ankle pain medially.

Adult↗
PubMed2000

Measles vaccine immunogenicity and antibody persistence in 12 vs 15-month old infants.

HYPOTHESIS: Maternal measles immunity in the United States today is primarily vaccine induced, with corresponding lower antibody titers in infants, as compared to infants born in an earlier era to mothers with naturally acquired measles immunity. We hypothesized that, due to lower titer of passively transferred maternal measles antibody, administration of measles vaccine at 12 months of age would result in seroconversion and antibody persistence comparable to vaccination at 15 months of age. POPULATION: Children at both an urban hospital and a suburban clinic. METHODS: Informed consent was obtained from mothers for the infants to receive M-M-R(R)II vaccine at either 12 or 15 months and to have serum samples obtained before vaccination and 4 weeks post-vaccination (PV). Between 9 and 39 months PV, a third serum sample was obtained from 28% of seroconverters. A diary of adverse experiences was kept for 3 weeks PV. Sera were assayed by a microneutralization assay (NT) and an enzyme immunoassay (EIA) for measles antibody. RESULTS: Both age groups tolerated vaccination well with minor and transient side effects. Forty-four of 47 (94%) 12-month-old infants seroconverted by NT, compared to 45 of 46 (98%) 15-month-olds (p=NS). There was no statistically significant decline in median NT titers or EIA titers in nineteen 12-month-olds and thirteen 15-month olds followed for 9-39 months PV. CONCLUSION: This study showed comparable serologic responses in 12- vs 15-month-old infants born to measles vaccine-immune mothers; however, the sample size was too small to have adequate power and further study is indicated. Titers of antibody were constant in both the 12-month-old and the 15-month-old infants, over a 9-39 month period, suggesting that waning immunity over this period of time is not a problem in either age group.

Age Factors↗
PubMed2000

Telephone counseling as adjuvant treatment for nicotine replacement therapy in a "real-world" setting.

BACKGROUND: Physicians prescribing nicotine replacement therapy (NRT), or health plans covering NRT, often want their patients to receive adjuvant behavioral treatment. However, how to do that in a "real world" is unclear. This paper reports results from a public health program that uses proactive telephone counseling as support for physician advice and provides adjuvant treatment for NRT users. METHODS: Participants were NRT users (N = 8,832) who called the California Smokers' Helpline, a statewide cessation service that provides proactive counseling, one session before NRT use and multisessions after the smokers received NRT. After receiving NRT, some participants discontinued the counseling while others continued with follow-up sessions. A subset of the 8,832 participants (n = 664) was interviewed 13 months later for quitting status. RESULTS: After receiving NRT, 79% of the participants continued with counseling and received 4.2 sessions on average, while 21% of them received only one session. Overall, 82.8% of all participants made a quit attempt. Nicotine patch users were more likely to make an attempt than nicotine gum users (85.2% vs 66.3%), but the relapse probability was the same for these attempts. Those who received multiple counseling were more likely to make an attempt than those receiving single counseling (84.4% vs 77.1%) and were more likely to stay quit for 1 year (25.6% vs 16.1%). CONCLUSIONS: Proactive telephone counseling is a promising adjuvant treatment for NRT users in a "real-world" setting: a convenient referral service for supporting health plans or physicians who advise their patients to quit smoking.

Adolescent↗
PubMed2000

A holistic model for matching high-tech hearing aid features to elderly patients.

Successful hearing aid fittings using high-technology features for elderly patients require consideration of factors beyond results obtained from routine audiologic evaluations. A holistic hearing aid selection, fitting, and evaluation approach that considers patient characteristics from communication, physical, psychological, and social assessment domains is presented here along with a checklist and flowcharts for matching high-tech hearing aid features to older persons who are hearing aid candidates.

Aged↗
PubMed2000

Children's phoneme identification in reverberation and noise.

This study assessed the effects of reverberation, noise, and their combination on listeners' identification of consonants and vowels in naturally produced nonsense syllables presented at different sensation levels (re: speech recognition threshold). A secondary purpose of this study was to assess listeners' identification of voicing, manner, and place of articulation for consonants at 50 dB SL in the reverberation, noise, and combined conditions. Listeners, aged 6-30 years, identified consonant-vowel-consonant-vowel (CVCV) stimuli presented at four different sensation levels (re: speech recognition threshold) of 30, 40, 50, and 60 dB SL in 4 listening conditions: (a) an optimal listening situation (no reverberation, no noise), (b) reverberation only (1.3 seconds), (c) noise only (+13 dB S/N against a multitalker babble), and (d) reverberation plus noise. Results showed that all listener groups achieved maximum consonant identification performance at 50 dB SL. Vowel identification scores were unaffected by SL. Statistical analyses revealed that children's ability to identify consonants varied according to listening condition. For example, children's consonant identification abilities reached adult-like levels of performance at about age 14 years in the reverberation-only and noise-only listening conditions. However, in the reverberation-plus-noise listening condition, children's consonant identification abilities do not mature until the late teenage years. The ability to identify vowels, on the other hand, develops much earlier. A feature analysis of the consonant data showed that for all 3 features (voicing, manner, and place), identification scores were highest in the control condition, similar for the reverberation-only and noise-only conditions, and lowest in the reverberation-plus-noise condition. Voicing was easier for listeners to identify than manner or place of articulation features in reverberation and noise. Taken together, these results suggest that the ability to identify speech in reverberation and noise reaches adult-like level of performance at different ages for different components of the speech signal.

Adolescent↗
PubMed2000

The transformative process of residency education.

The author explores a model for transformative learning proposed by the education scholar Victoria Marsick. He begins by outlining Marsick's eight principles (or outcomes) of transformative learning: increased autonomy; increased independence; the ability to separate one's feelings and opinions from those of others; the ability to critically and respectfully examine the views of others; the ability to set personal and professional goals; the ability to see how one's actions affect the system in which one works; the ability to balance and choose among conflicting priorities and at some point transcend self-interest; and the ability to acknowledge one's role in constructing one's reality. Using illustrative examples from his experiences as a resident and a teacher of residents, the author describes each principle of the transformative model. He then suggests how educators can use these principles to ensure a transformative residency experience by which novice professionals become reflective and confident practitioners.

Clinical Competence↗
PubMed2000

Bacteriologic and clinical efficacy of amoxicillin/clavulanate vs. azithromycin in acute otitis media.

OBJECTIVES: To compare the bacteriologic and clinical efficacy of amoxicillin/clavulanate and azithromycin in patients with acute otitis media (AOM), particularly the ability to eradicate the predominant AOM pathogens from middle ear fluid as assessed by mandatory second tympanocentesis. METHODS: In this single blind study 238 infants and children with AOM were randomized to receive amoxicillin/clavulanate (45/6.4 mg/kg/day in two divided doses for 10 days) or azithromycin (10 mg/kg on Day 1, then 5 mg/kg daily on Days 2 through 5). Tympanocentesis was performed before the first dose and repeated on Day 4, 5 or 6. Clinical response was assessed at end of therapy between Days 12 and 14 and at follow-up between Days 22 and 28. RESULTS: Amoxicillin/clavulanate was significantly more likely to eradicate all bacterial pathogens [83% (54 of 65) vs. 49% (35 of 71), P = 0.001] and Haemophilus influenzae [87% (26 of 30) vs. 39% (13 of 33), P = 0.0001] from middle ear fluid than was azithromycin. Amoxicillin/clavulanate was also more likely to eradicate Streptococcus pneumoniae, but the difference was not statistically significant [90% (18 of 20) vs. 68% (13 of 19) [corrected], P = 0.095]. On Days 12 to 14, signs and symptoms were more likely to resolve completely or improve in all culture-positive patients [86% (60 of 70) vs. 70% (51 of 73), P = 0.023] and in those with H. influenzae infections [91% (30 of 33) vs. 65% (22 of 34), P = 0.010] who received amoxicillin/clavulanate compared with those who received azithromycin. Otherwise there were no significant differences between groups in clinical outcomes on Days 12 to 14 or at follow-up. CONCLUSIONS: Our findings indicate that amoxicillin/clavulanate has superior bacteriologic and clinical efficacy compared with azithromycin in children with AOM.

Amoxicillin-Potassium Clavulanate Combination↗
PubMed2000

A centralised telephone service for tobacco cessation: the California experience.

OBJECTIVE: To provide an overview of the California Smokers' Helpline, an increasingly popular telephone program for tobacco cessation in California since 1992. As many states, regions, and nations are contemplating various telephone programs as part of large scale anti-tobacco campaigns, this paper presents a practical model. DESIGN: The Helpline provides Californians with free cessation services that include counselling, self help quit kits, and cessation related information. Services are provided in six spoken languages plus a line for the hearing impaired. The program is promoted statewide by media campaigns, health care providers, local tobacco control programs, and the public school system. SETTING: The Helpline is centrally operated through the University of California, San Diego and provides services statewide via telephone. RESULTS: The Helpline has served over 100 000 tobacco users and has become the chief cessation resource for the Comprehensive Tobacco Control Program in California. Media was the most important referral source for Helpline callers (50%), followed by health care providers (20%). About one third of the callers were ethnic minorities and 17% were 24 years old or younger. Compared to California smokers in general, the callers were more dependent on nicotine and more likely to live with other smokers, but they were also more likely to have tried to quit recently and were more ready to try again. Two randomised trials have demonstrated the efficacy of the Helpline's counselling protocol. CONCLUSION: A centralised helpline operation can be an accessible and effective service for tobacco users and should be included in any large scale, comprehensive tobacco control program.

Adolescent↗
PubMed2000

The utility of screening chest radiographs for flight physicals.

Previous studies have shown low efficacy of screening chest radiographs in various populations. Findings of approximately 3,500 screening chest radiographs performed for flight duty were reviewed to determine the rate of detection of significant abnormalities. There were abnormal findings in 107 chest radiographs (3%). Fifty-five of these (1.6% of total), after additional evaluation, were found to be false positive. Only two medically significant conditions were found in the screening population. Based on our data, routine screening of flight duty applicants does not appear to be justified.

Adolescent↗
PubMed1999

Stability of levofloxacin in an extemporaneously compounded oral liquid.

The stability of levofloxacin in an extemporaneously compounded oral liquid was studied. A suspension of levofloxacin 50 mg/mL was prepared from commercially available 500-mg levofloxacin tablets and equal amounts of Ora-Plus and Strawberry Syrup, NF, to make a final volume of 60 mL. Six identical volumes of the suspension were prepared in amber plastic prescription bottles. Three bottles were stored at 23-25 degrees C, and three were stored at 3-5 degrees C. Immediately after preparation and at 8, 15, 29, and 57 days, samples were visually inspected and assayed in duplicate by high-performance liquid chromatography; pH was also determined. At least 99% of the initial levofloxacin concentration remained in all samples throughout the study period. The color, odor, and pH of all the samples did not change appreciably. An extemporaneously compounded oral liquid formulation of levofloxacin 50 mg/mL in a 1:1 mixture of Ora-Plus and Strawberry Syrup, NF, was stable at 23-25 or 3-5 degrees C for up to 57 days.

Anti-Infective Agents↗
PubMed1999

Urticaria following varicella vaccine associated with gelatin allergy.

An uncommon reaction to varicella vaccine has been urticaria. Based on two reports of urticaria believed to be due to gelatin in recipients of measles-mumps-rubella vaccine, we suspected gelatin as the cause of generalized urticaria in two children after varicella vaccination. Intradermal testing with gelatin yielded a wheal and flare reaction in both children. We conclude that children known to be allergic to gelatin should not receive Oka/Merck varicella vaccine (VARIVAX).

Allergens↗