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Biomedical subjects

C E Johnson

Publications and source records attributed to C E Johnson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Internally stabilized spine: optimal choice of frequency-encoding gradient direction during MR imaging minimizes susceptibility artifact from titanium vertebral body screws.

In 18 vertebral bodies with titanium fixation screws and in a phantom model, visualization of the vertebral body marrow was improved and susceptibility artifact was reduced on T1-weighted spin-echo magnetic resonance images when the direction of the frequency-encoding gradient was parallel to the long axis of the screw. A perpendicular direction improved image quality only when the region of interest was adjacent to the tip of the screw. In the phantom, the length of the screw was statistically significantly increased and the width and area were reduced (P <.001) when the gradient was parallel to the long axis of the screw.

Adult↗
PubMed1997

Isradipine therapy in hypertensive pediatric patients.

OBJECTIVE: To evaluate the dosage and effectiveness of isradipine to control acute or chronic hypertension in pediatric patients. DESIGN: Retrospective medical record review. SETTING: University teaching hospital. PARTICIPANTS: Hospitalized pediatric patients aged 1 day to 16 years with hypertension treated with isradipine between January 1994 and March 1996. MEASURES: Patient age, gender, weight, disease states, current medications, isradipine dosage and formulation, pre- and postsystolic, and pre- and postdiastolic blood pressure measurements with each dose of isradipine. RESULTS: Fifty-three patients with a mean age of 5.8 +/- 4.0 years were evaluated. A mean change in the blood pressure measurements taken before the first dose of isradipine compared with the values recorded after the last dose or at discharge for all patients was -11.8% +/- 12.5% and -17.4% +/- 19.6%, respectively, for systolic and diastolic pressure. The mean dosage of isradipine in 46 patients who received regularly scheduled doses was 0.38 +/- 0.22 mg/kg/d. Patients who demonstrated a response received a mean dosage of 0.40 +/- 0.20 mg/kg/d. The total daily dosage was administered in one dose for 1 patient, two doses for 15 patients, three doses for 27 patients, and four doses for 3 patients. CONCLUSIONS: Isradipine was an effective antihypertensive agent to reduce the systolic and/or diastolic blood pressure 10% or more compared with pretreatment measurements in 43 (81%) of 53 pediatric patients. The mean dosage was 0.38 +/- 0.22 mg/kg/d, most frequently administered in two or three equally divided doses, which is higher than the normal recommended dosage for adults.

Adolescent↗
PubMed1997

A long-term prospective study of varicella vaccine in healthy children.

BACKGROUND: Studies in Japan and the United States have shown that varicella vaccine is both safe and efficacious. In 1984, we undertook a 10-year prospective study using a research lot of Oka/Merck varicella vaccine to assess antibody persistence and breakthrough chickenpox rates. In 1987, we began a similar prospective study with lots made in production facilities that ended after 6 years because many children were given a second dose. The purpose of this study is to report humoral antibody persistence and breakthrough chickenpox rates after 6 to 10 years of prospective follow-up. METHODS: One hundred forty-three seronegative children received a research lot (950 plaque-forming units/dose) with 97.9% seroconversion by an assay for fluorescent antibody to membrane antigen (FAMA). One hundred thirty-eight children received production lots (1145 to 3265 plaque-forming units/dose) with 93.5% seroconversion. Yearly chickenpox exposure surveys were completed by phone, and children were seen by a study nurse whenever chickenpox was suspected. A subset in each group had serum collected every 2 years and tested for FAMA antibody. RESULTS: In the research group there have been 25 cases of chickenpox in 137 seroconverters in a period of more than 10 years (yearly rate of 1.7%). In the production lot group there have been 22 cases of chickenpox in 129 seroconverters in a 6-year period (yearly rate of 2.8%). In the research group the median titer rose from 1:16 to 1:64 between 1 and 10 years. In the production group, the median titer did not change between 1, 2, and 4 years. Median antibody titers were compared between the research and production groups at 1, 2, and 4 years and did not differ. The rate of development of modified chickenpox has not increased with time since vaccination, and neither has the case severity. Children with FAMA titers </=8 at 6-weeks' postvaccination were four times more likely to develop chickenpox than those with titers >/=64. CONCLUSIONS: 1) Modified chickenpox has occurred in approximately 2% to 3% of vaccinees per year, regardless of the vaccine lot given. 2) FAMA titers have risen between 1 and 10 years in research lot recipients and remained the same in production lot recipients. 3) The likelihood of modified chickenpox developing is inversely related to the 6-week postvaccination FAMA titer.

Adolescent↗
PubMed1997

Term newborns who are at risk for sepsis: are lumbar punctures necessary?

OBJECTIVES: To determine: (1) whether a lumbar puncture (LP) is indicated in asymptomatic full-term newborns delivered by mothers at risk of intrapartum sepsis; and (2) whether gentamicin improves bacterial coverage for such newborns when used with ampicillin. DESIGN: A retrospective chart review from 1987 through 1993 of all newborns with positive blood and/or cerebrospinal fluid cultures in the first 7 days of life. METHODS: Pregnant women were screened in the second trimester for group B streptococci and given ampicillin during labor if two or more risk factors were present: group B streptococci colonization, maternal fever or leukocytosis, rupture of membranes at more than 18 hours, foul-smelling amniotic fluid, and fetal tachycardia. After sepsis evaluation (LP, blood culture, white blood cell count, and differential), asymptomatic infants received ampicillin and gentamicin for 48 to 72 hours unless cultures grew pathogens. RESULTS: Of approximately 24 452 full-term births in 7 years, 7% (1712) had evaluations for symptoms of sepsis, and 14% (3423) were asymptomatic but had evaluations for maternal risk factors. There were 11 cases of meningitis, all involving symptomatic newborns; 10 of these 11 had positive blood cultures for the same organism. In asymptomatic infants, none of the 3423 had meningitis (95% confidence interval, 0 to 0.0008), although 35 grew contaminants. Of 73 pathogens isolated from blood or cerebrospinal fluid, 7 (9.5%) were resistant to ampicillin. Addition of gentamicin provided coverage for only 2 of these 7 pathogens. Of 5135 infants who received ampicillin and gentamicin, only 2 required gentamicin for improved coverage. CONCLUSIONS: (1) LP is unnecessary in asymptomatic full-term newborns. (2) Empiric coverage for asymptomatic newborns with maternal risk factors need not include gentamicin at all hospitals, because it only improved the coverage of ampicillin alone from 90% to 93% of pathogens, but it exposed more than 5000 infants to the side effects of gentamicin. (3) The presence of leukopenia (<5000 white blood cells/mm) is highly predictive of bacteremia.

Ampicillin↗
PubMed1996

The effects of capitation payment on the organizational structure of medical group practices.

This study explores the effects of capitation payment on the structural elements used by medical group practices to control physician-directed use of resources and the quality of patient care. Forty-five medical groups located in the highly competitive Minneapolis/St. Paul metropolitan area were studied. The range of capitation payment in these medical group practices is from 2% to 87%. Although the practices vary considerably in the extent to which they have developed these control mechanisms, it does not appear that capitation payment is a major factor influencing that pattern. It appears that many of these medical group practices either use less formal mechanisms than those included in this study to control resource use and the quality of care or use none at all. In either event, the data suggest that the effects of capitation payment on the structure of medical practices may be overestimated.

Capitation Fee↗
PubMed1996

Antibody persistence after primary measles-mumps-rubella vaccine and response to a second dose given at four to six vs. eleven to thirteen years.

BACKGROUND: Since 1989 the American Academy of Pediatrics and the ACIP have recommended a second dose of measles-mumps-rubella vaccine (M-M-R-II) at either school entry or age 11 to 13 years. Unfortunately few studies are available to compare responses to vaccine at the two ages. We performed a prospective trial to determine the persistence of antibody to measles, mumps and rubella vaccination in two age groups and the response to a second dose given at either 4 to 6 or 11 to 13 years. METHODS: Thirty-eight children 4 to 6 years old and 57 children 11 to 13 years old were given a second dose of M-M-R-II as they presented for yearly examinations. All had received the first dose at > or = 15 months of age. Measles and rubella antibody were measured by enzyme-linked immunosorbent assay (ELISA) and neutralizing antibody (NT) assay, and mumps antibody was measured by an ELISA method only. An IgM-ELISA antibody assay for measles was used in selected children. Prevaccination and 3- to 4-week post-vaccination sera were obtained. Measles ELISA, measles-neutralizing antibody (NT) and rubella-neutralizing antibody (NT) assays were performed in all children. Seventy-nine of the 95 children had sufficient sera for repeat measles tests, as well as mumps and rubella ELISA determinations. RESULTS: Before the second dose ELISA seropositivity rates for measles and mumps were not significantly different between the two groups. Rubella ELISA seropositivity was 67% in 11- to 13-year-olds, compared with 90% in 4- to 6-year-olds (P < 0.01), suggestive of waning immunity. Rubella NT seropositivity was also lower in 11- to 13-year-olds than in 4- to 6-year-olds (63% vs. 100%, P < 0.01). After revaccination, 100% of the children become seropositive for all 3 antibodies. We performed measles IgM-ELISA testing on all 17 measles-seronegative children, as well as 15 seropositive children and 19 children who were 1 month postvaccination with the first M-M-R-II at 15 months. The purpose was to determine whether the seronegative children were primary or secondary failures. Five of the 17 children with undetectable pre-second dose antibody made IgM measles antibody after revaccination, suggesting that they were primary vaccine failures. CONCLUSIONS: Because all children became seropositive after revaccination, the age of administration can be based on the convenience of vaccine scheduling. However, in view of the apparent decline in rubella antibodies at 11 to 13 years, future studies of rubella vaccination should address the issue of whether earlier boosting leads to greater susceptibility at the time of reproductive age.

Adolescent↗
PubMed1995

Stability of ursodiol in an extemporaneously compounded oral liquid.

The stability of ursodiol in an extemporaneous oral liquid formulation refrigerated at 4 degrees C for 35 days was studied. A suspension was prepared by opening commercially available 300-mg capsules of ursodiol, adding Glycerin, USP, to form a paste, and then adding Simple Syrup, NF. A control solution was prepared from analytical-grade ursodiol powder in simple syrup. The final concentration of ursodiol in both formulations was 60 mg/mL. Three samples of each preparation were stored in 2-oz, amber glass prescription bottles in the dark at 4 degrees C. Immediately after preparation and at 7, 14, 21, 28, and 35 days, samples were visually inspected, tested for pH, and assayed in duplicate by high-performance liquid chromatography. Stability was defined as the retention of more than 90% of the initial concentration. On day 35, the mean percentage of the initial ursodiol concentration remaining was 96.5% in the suspension made from powder-filled capsules, and 100.6% in the suspension made from analytical-grade powder. The color, odor, and pH of the samples did not change appreciably over the study period. An extemporaneously compounded oral liquid preparation of ursodiol in simple syrup was stable under the conditions studied for up to 35 days.

Administration, Oral↗
PubMed1995

Pathophysiology and treatment of alpha 1-antitrypsin deficiency.

The pathophysiology of alpha 1-antitrypsin (AAT) deficiency and the use of alpha 1-proteinase inhibitor therapy in the management of emphysema caused by AAT deficiency are described. AAT deficiency is the most common genetic cause of liver disease in children and emphysema in adults. However, not all patients with AAT deficiency develop hepatic or pulmonary involvement. Changes in the composition of the AAT molecule have been associated with AAT dysfunction in liver disease, whereas lung disease occurs when AAT concentrations are reduced. A definitive diagnosis can be made through serum AAT phenotype determination. Therapy for liver disease induced by AAT deficiency consists of supportive measures. Therapy for pulmonary disease due to AAT deficiency includes AAT augmentation therapy along with supportive measures. The available product, alpha 1-proteinase inhibitor, is derived from fractionated plasma and has similar biological activity to native serum AAT. Clinical trials have demonstrated a positive effect on serum and lung concentrations of AAT with few adverse events. Two recombinant forms of AAT have also been developed; however, few trials have been published evaluating their safety and efficacy in AAT-deficient patients. Many questions remain unanswered concerning AAT deficiency and replacement therapy. AAT augmentation therapy appears to reduce the progression of emphysema in some AAT-deficient patients.

Clinical Trials as Topic↗
PubMed1995

Stability of itraconazole in an extemporaneously compounded oral liquid.

The stability of itraconazole in an extemporaneously compounded oral liquid formulation was studied. A suspension was prepared from the beads contained in commercially available 100-mg itraconazole capsules and sufficient Simple Syrup, NF, to make a final volume of 60 mL. The final concentration of itraconazole in the suspension was 40 mg/mL. Three identical volumes of each suspension were prepared and stored in 2-oz capped, amber glass prescription bottles and refrigerated at 4 degrees C (range, 2-6 degrees C). Immediately after preparation and at 7, 14, 21, 28, and 35 days, samples were visually inspected and assayed in duplicate by high-performance liquid chromatography; the pH of the samples was also determined. On day 35, the mean +/- S.D. percentage of initial itraconazole concentration remaining in the three suspensions was 95.3 +/- 2.2%. The color, odor, and pH of the samples did not change appreciably over the study period. Itraconazole 40 mg/mL in an oral liquid compounded from simple syrup and beads from capsules, stored in amber glass bottles, was stable for 35 days at 4 degrees C.

Administration, Oral↗
PubMed1995

Resolution of middle ear effusion in newborns.

OBJECTIVES: To determine the natural history of middle ear effusion (MEE) in newborns and compare the results of pneumatic otoscopy with tympanometry and acoustic reflex measurements in the evaluation of the middle ear of neonates. DESIGN: A descriptive natural history study with comparison of three evaluation methods for MEE. SETTING: County hospital nursery and pediatric clinic. PARTICIPANTS: Sixty-eight full-term, healthy neonates were studied on day 1 of life; 65 on day 2; and 24 on day 3. Thirty-eight infants returned at 2 weeks of age, and from this group, 23 returned at 2 months of age. INTERVENTIONS: Two independent observers performed otoscopy. An audiologist performed tympanometry and ipsilateral acoustic reflex measurements. Infants were evaluated daily from birth by all three methods for up to 3 days. MAIN OUTCOME MEASURE: The time to resolution of MEE as determined by three methods. RESULTS: In the first 3 hours of life, all babies examined had MEE diagnosed in both ears. By the third day, MEE apparently had resolved in 73% of ears by otoscopy, 88% by acoustic reflex measurements, and 92% by tympanometry. At 2 weeks, MEE was present by otoscopy in 13% (10/75 of ears). These were primarily newly acquired MEEs. Interobserver agreement by otoscopy as determined by kappa scores was moderate on days 1 and 3, poor on day 2, and excellent at 2 weeks and 2 months. CONCLUSIONS: Middle ear effusion diagnosed by otoscopy apparently resolves in 72 hours in most neonates. Interobserver agreement of otoscopists was excellent after babies were discharged from the nursery, suggesting that pneumatic otoscopy can be used to diagnose MEE in neonates this age. Most MEEs that are diagnosed 2 weeks and 2 months after birth are new and asymptomatic.

Acoustic Impedance Tests↗
PubMed1995

Continuous versus intermittent nebulized terbutaline: plasma levels and effects.

The purpose of this investigation was to compare continuous versus intermittent nebulization of a beta 2-agonist, terbutaline, to determine whether differences exist in plasma concentrations or adverse cardiovascular effects of the drug with these two techniques for its administration. Sixteen children 6 to 16 yr of age, admitted for acute asthma, were enrolled in this randomized double-blind clinical trial. Nebulization of 16 mg of terbutaline over an 8-h period was performed either continuously or intermittently, with a dose of 4 mg given over 20 min every 2 h. The peak plasma terbutaline concentration for the intermittent nebulization treatment (INT) group (5.1 +/- 2.1 ng/ml) occurred 1 h after the fourth inhalation treatment and was similar to the peak concentration for the continuous nebulization treatment (CNT) group, which was reached at the end of the 8 h period (4.7 +/- 2.3 ng/ml). The maximum heart rate increase for the INT group (19.6 +/- 18.3 bpm) occurred 1 h after the fourth dose and was similar to the peak observed in the CNT group (19.6 +/- 19.2 bpm), which occurred after 3 h. Similar increases in systolic and decreases in diastolic pressures were observed for the INT and CNT groups. No evidence of serious adverse myocardial complications was seen in either group, as evidenced by measurements of the MB fraction of creatine phosphokinase (CPK-MB) and Holter-monitor recordings. Continuous nebulization of the terbutaline produces similar plasma concentrations and cardiovascular physiologic responses as intermittent nebulization.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Inhalation↗
PubMed1994

Stability of isradipine in an extemporaneously compounded oral liquid.

The stability of isradipine in an extemporaneously compounded oral liquid was studied. A suspension was prepared from the powder of commercially available 5-mg isradipine capsules and sufficient Simple Syrup, NF, to make a final volume of 50 mL. A control suspension was prepared from analytical-grade isradipine powder and Simple Syrup, NF. The final concentration of isradipine in both suspensions was 1 mg/mL. Three identical volumes of each suspension were stored in 2-oz amber glass prescription bottles, which were stored at 4 degrees C. Immediately after preparation and at 7, 16, 22, 28, and 35 days, samples were visually inspected and assayed in duplicate by high-performance liquid chromatography; the pH of the samples was also determined. At least 95% of the initial isradipine concentration remained throughout the study period in all samples of both suspensions. Color, odor, and pH did not change appreciably. Isradipine 1 mg/mL in an oral liquid compounded from Simple Syrup, NF, and powder from capsules was stable for at least 35 days in amber glass bottles at 4 degrees C.

Administration, Oral↗
PubMed1994

Stability of ganciclovir sodium and amino acids in parenteral nutrient solutions.

The stability of ganciclovir sodium and amino acids in parenteral nutrient solutions was studied. Three admixtures of ganciclovir sodium plus parenteral nutrient solution were prepared, one containing ganciclovir sodium 0.83 mg/mL, 1% amino acids, and 10% dextrose injection; one containing ganciclovir sodium 1.4 mg/mL, 2.5% amino acids, and 10% dextrose injection; and one containing ganciclovir sodium 1.4 mg/mL, 5% amino acids, and 25% dextrose injection. The solutions were visually inspected for precipitates, color change, and gas formation and were tested for pH. High-performance liquid chromatography was used to measure the concentration of ganciclovir and 16 amino acids in each admixture immediately and one, two, and three hours after preparation. There was no evidence of visual incompatibility in any of the admixtures, and pH did not vary appreciably during the study. The mean ganciclovir sodium concentration remaining was greater than 100% of the initial concentration for all the admixtures at one, two, and three hours. The mean amino acid concentration remaining in the admixtures with 2.5% or 5.0% amino acids was greater than 90% of the initial concentration for each amino acid at one, two, and three hours. The mean amino acid concentration remaining in the admixture with 1% amino acids was greater than 90% of the initial level at one and two hours. Ganciclovir sodium 0.83 mg/mL was stable for at least three hours in parenteral nutrient solution with 1% amino acids, and ganciclovir sodium 1.4 mg/mL was stable for at least three hours in admixtures with 2.5% or 5% amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗