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Biomedical subjects

B Nelson

Publications and source records attributed to B Nelson.

At least 73 records · Page 4Linked to original sources
PubMed1992

The dexamethasone suppression test in children and adolescents: a review and a controlled study.

Dexamethasone Suppression Test (DST) studies conducted in children and adolescents are reviewed, together with factors hypothesized to explain discrepancies in rates of DST nonsuppression across studies. These factors are then examined in a controlled study of 27 adolescents with major depressive disorder (MDD) and 34 normal controls (NC). Subjects were given 1 mg of dexamethasone at 11:00 PM, and the following day serum samples for cortisol were collected each hr from 8 AM to 11 PM through an indwelling catheter. There were no significant differences found between the MDD and NC subjects on any postdexamethasone cortisol measure. Further, cortisol suppressors and nonsuppressors were not distinguished by any of the hypothesized factors identified from the review, including inpatient status, presence of suicidality, endogenous features, psychotic symptoms, or prior history of MDD. Questions about the appropriateness of the 1 mg dose of dexamethasone (currently the standard dose used with adolescents) are raised, together with a discussion of the effects of stress on DST findings.

Adolescent↗
PubMed1992

Significant factors in the disinfection and sterilization of flexible endoscopes.

BACKGROUND: Many nosocomial infection outbreaks have been linked to improper disinfection of the flexible endoscopes used in hospitals and clinics. The objective of this study was to evaluate the efficacy of scope disinfection with glutaraldehyde and hydrogen peroxide in manual and mechanical protocols. METHODS: Bacillus subtilis and Pseudomonas cepacia were the test organisms. Each channel in two different endoscopes was seeded and evaluated separately. Residual chemical germicide levels in the channels and in the work environment were also measured. RESULTS: Parametric analyses were carried out on log transformations of number of colony-forming units recovered. Repeated measures analysis demonstrated that both the type of disinfectant and the method of washing were significant factors for disinfection. CONCLUSIONS: Hydrogen peroxide proved to be more efficacious than glutaraldehyde for killing or removing B. subtilis in a 10-minute contact period. Automatic disinfection was more efficacious than manual disinfection for killing or removing B. subtilis in a 10-minute contact period. The channel being disinfected also proved to be a significant factor, with carbon dioxide and elevator channels the most difficult to disinfect consistently.

Bacillus subtilis↗
PubMed1992

Dexamethasone suppression test in children with major depressive disorder.

The authors report a study of 24-hour serial cortisol determinations, measured during baseline and after the administration of 0.25 and 0.5 mg of dexamethasone in a sample of predominantly outpatient children with major depressive disorder, nonaffective psychiatric controls, and normal controls. In this sample, 24-hour baseline cortisol and the dexamethasone suppression test (DST) do not discriminate between the three groups. In addition, the authors measured 24-hour serum dexamethasone levels. There were no significant between group differences in serum dexamethasone. These results raise questions as to the utility of this test in the diagnosis of affective disorders in children. Possible reasons for the discrepancies in the dexamethasone suppression test results between in- and outpatient studies are discussed.

Administration, Oral↗
PubMed1992

Regulation of sleep and growth hormone in adolescent depression.

This article reviews findings of sleep, growth hormone (GH), and cortisol measures from a number of separate controlled studies of prepubertal and adolescent depression carried out by Puig-Antich and colleagues since 1978. New data are presented comparing 24-hour GH measures in adolescents with major depressive disorder (MDD) (N = 44; mean age = 14.8 +/- 2.0) to normal control adolescents (N = 37; mean age = 15.3 +/- 1.5). There were no significant overall group differences in summary GH measures between MDD and normal controls. Splitting the MDD group on the basis of suicidality (definite plan or attempt) (N = 20), revealed a significant blunting of sleep GH compared to the nonsuicidal group (N = 24). These results are discussed in the context of the other sleep and neuroendocrine findings in this population, with evidence for dysregulation around sleep onset. The influences of development on sleep and GH regulation are also considered.

Adolescent↗
PubMed1992

The use of Ender nails in femoral shaft fractures: what are the remaining indications?

The use of Ender nails for the treatment of femoral shaft fractures has been described as technically easier and less time consuming than current intramedullary nailing techniques. We reviewed our results with unlocked Ender nails in 26 stable and 17 unstable fracture patterns an average of 3-4 years after injury. Because of continued instability, 42% of the stable and 76% of the unstable groups required adjunctive stabilization in the form of skeletal traction, a cast, or an external fixator. Additionally, nail migration and shortening and loss of motion at the knee were seen in 14 fractures in each group. Although two thirds of the patients with stable fracture patterns obtained good or excellent results, no outcome in the unstable group was rated excellent and only 19% were considered good. We therefore recommend that rigid locked intramedullary nails be used in femoral diaphyseal injuries. The use of Ender nails should be limited to stable fracture patterns and locked with screws or wires. They may be particularly useful for fractures in femora with small medullary canals (less than or equal to 8 mm), fractures below noncemented femoral prostheses, and fractures in young children requiring intramedullary stabilization without injuring the physeal plates.

Adolescent↗
PubMed1992

The dexamethasone suppression test in adolescent outpatients with major depressive disorder.

OBJECTIVE: The purpose of the study was to determine whether the dexamethasone suppression test (DST) would discriminate between outpatient adolescents with major depressive disorder and normal adolescent comparison subjects. METHOD: Depressed patients were accepted into the study only if they fulfilled the Research Diagnostic Criteria for major depressive disorder. The depressed subjects (N = 44) and the normal subjects (N = 38) were studied in the same environment and under the same conditions. The subjects received 1 mg of dexamethasone at 11:00 p.m. The next day, blood for determining plasma cortisol concentrations was drawn through an indwelling catheter every 60 minutes from 8:00 a.m. until 11 p.m. RESULTS: After dexamethasone, the cortisol levels of the adolescents with major depressive disorder and the normal subjects were not significantly different. Only six (14%) of the depressed subjects and one (3%) of the normal subjects showed evidence of nonsuppression (cortisol value greater than 5 micrograms/dl). Analyses of subgroups of the depressed patients based on suicidal tendencies and endogenous subtype also failed to reveal significant differences in cortisol values. Estimates of the severity of depression showed significant negative correlations with cortisol values among the depressed patients. CONCLUSIONS: In contrast with previous studies of adolescent inpatients, the DST did not discriminate between the adolescent outpatients with major depressive disorder and the normal comparison subjects in this study. Possible reasons for the discrepancies, such as severity of the depression and inpatient status, are discussed.

Adolescent↗
PubMed1991

Electroencephalographic sleep measures in prepubertal depression.

Two nights of electroencephalographic (EEG) sleep recording were performed in a group of prepubertal subjects with major depressive disorder (MDD) (n = 36, mean age = 10.4, SD = 1.5) and age-matched normal control children (n = 18, mean age = 10.1, SD = 1.6). All subjects were medically healthy and free of medications at the time of the study. There were no significant group differences for any major sleep variable after the initial adaptation night in this study. One subgroup of MDD subjects (n = 8) showed reduced REM latency on both recording nights, decreased stage 4 sleep, and increased REM time; this subgroup had significantly higher severity scores for depression but did not otherwise appear to be clinically distinct from the rest of the MDD subjects. Overall, the results indicate that the EEG sleep changes associated with depression in adults occurred less frequently in prepubertal MDD subjects.

Adolescent↗
PubMed1991

Thyroid stimulating hormone response to thyrotropin in prepubertal depression.

In an effort to evaluate whether differences exist in the hypothalamic-pituitary-thyroid axis of depressed children, a thyrotropin releasing hormone (TRH) stimulation test was administered to 55 prepubertal subjects who were divided into three groups matched for age and sex: a depressed group (endogenous N = 15, nonendogenous N = 15), a psychiatric nondepressed control group (N = 16), and a normal control group (N = 9). Each subject was tested at two dosages of TRH, 2 micrograms/kg and 7 micrograms/kg. Increasing age and female sex were positively correlated with a greater thyroid stimulating hormone (TSH) response. TSH response to TRH was examined with subjects reclassified by severe suicidal ideation, severe aggression, and parental history of alcoholism. Results of this study are contrasted with the adult psychiatric literature.

Age Factors↗
PubMed1991

Hormonal responses to dextroamphetamine in depressed and normal adolescents.

Because of its neuroendocrine effects, amphetamine infusion has been used as a probe to investigate neurobiological correlates of depressive illness. In two separate studies, a total of 72 adolescents with major depressive disorder and 66 normal adolescents were given dextroamphetamine, 0.15 mg/kg, intravenously. Their cortisol, growth hormone, and prolactin responses were measured. These endocrine responses did not reliably distinguish adolescents with major depressive disorder from those without it, nor did they reliably delineate any specific depressive subgroup. These findings are compared with those from similar studies of adult depression.

Adolescent↗
PubMed1990

Biological and clinical effects of the combination of beta- and gamma-interferons administered as a 5-day continuous infusion.

A phase I trial involving continuous infusion of both beta- and gamma-interferon (IFN-beta and IFN-gamma) was conducted in 20 patients in order to determine whether combinations of high doses of IFN-beta and IFN-gamma were tolerable when administered under conditions which mimic conditions of in vitro antiproliferative studies. Patients received a 5-day continuous infusion of IFN-beta/IFN-gamma, followed by a 9-day rest period. Two cycles were administered. Doses of IFN-beta/IFN-gamma were escalated between 4 dose levels, with 5 patients per dose level. Dose-dependent side effects, consisting primarily of constitutional symptoms typical of those experienced with IFN, were observed. The maximally tolerated dose of continuous IFN-beta/IFN-gamma infusion was 3 x 10(6) units of IFN-beta and 200 micrograms of IFN-gamma. Dose-limiting side effects consisted of severe headache, fatigue, fever, and hepatic toxicity. No clinical responses were observed. Serum IFN was measurable only at the highest 3 dose levels. Only 5 patients (4 at the highest dose level) had total serum levels which exceeded 50 laboratory units/ml (55, 63, 800, 800, and 550 laboratory units/ml, respectively). In order to confirm the biological effectiveness of this schedule, we measured IFN-inducible proteins prior to therapy, 24 h after the initiation of the infusion, and at the completion of the 5-day infusion. 2'-5'-Oligoadenylate synthetase, serum beta 2-microglobulin, neopterin, and p78 levels all increased significantly, and serum tryptophan decreased significantly within 24 h after the initiation of treatment (P less than 0.0001). A dose-response effect was observed for serum beta 2-microglobulin, neopterin, and p78 (P less than 0.02). We retrospectively compared the results of this trial with those of another IFN-beta/IFN-gamma trial in which IFN-beta and IFN-gamma were administered by i.v. bolus. Within the limitations of a retrospective comparison, continuous infusion was less well tolerated than our previous schedule of bolus administration 3 times/week. However, the continuous infusion schedule appeared to be more effective in enhancing 2'-5'-oligoadenylate synthetase levels in mononuclear cells. We conclude that tolerable doses of IFN-beta and IFN-gamma do not result in serum IFN levels which produce significant synergistic antiproliferative responses in vitro. This study and other findings suggest that, unless higher doses can be achieved, combinations of IFN-beta and IFN-gamma are unlikely to have significant therapeutic activity.

2',5'-Oligoadenylate Synthetase↗
PubMed1990

EEG sleep in adolescents with major depression: the role of suicidality and inpatient status.

All night sleep EEG recordings were performed for three consecutive nights in 27 adolescents with a diagnosis of major depressive disorder (MDD) and 30 normal adolescent controls. Group comparisons between the entire MDD group and the normal controls revealed no significant diagnostic group differences for any of the major sleep variables. Analyses within subgroups of MDD adolescents, however, revealed heterogeneity of EEG sleep findings in association with suicidality and inpatient status. The findings of this study suggest that the discrepancies among the EEG sleep studies in adolescent MDD may be accounted for by the relative proportions of inpatients, suicidality, or bipolarity within the MDD sample being studied.

Adolescent↗
PubMed1989

Cortisol secretion in adolescents with major depressive disorder.

Plasma cortisol concentrations were determined every 20 min for 24 h, in a nonstressful environment, among 48 rigorously assessed, mostly outpatient, drug-free adolescent subjects during an episode of major depression (MDD) and among 40 normal adolescent subjects. There were no significant differences in the 24-h mean, peak, or nadir, or the time of the nocturnal rise, in plasma cortisol in the 2 groups. Analyses of different subgroups of MDD adolescents according to suicidality, severity of depression, separation anxiety, psychotic subtype, endogenicity, duration of episode, and sex also revealed no significant group differences. Only one adolescent (with MDD) was identified clearly as a hypersecretor of cortisol. These results indicate that abnormalities of spontaneous cortisol secretion are an unusual finding among adolescents with major depression when studied in a nonstressful environment.

Adolescent↗
PubMed1989

Failure of prediction of liver function test abnormalities with the urine urobilinogen and urine bilirubin assays.

A prospective observational study of 229 cases was conducted in a busy ambulatory care setting to evaluate the sensitivity, specificity, predictive values, and accuracy of spot urine urobilinogen and urine bilirubin assays as screening tests for serum liver function test (LFT) abnormalities. Both urine tests exhibited remarkably similar characteristics overall once they were adjusted to maximize accuracy and predictive values (occurring at a normal or abnormal "threshold," respectively, of 3.4 or 5.07 mumol/d for urobilinogen and 0 or 1+ for urine bilirubin). The percentage of cases correctly identified were 81% to 83% for serum bilirubin assays, 68% to 72% for other LFTs, but only 62% to 63% for screens for cases with at least one abnormal LFT finding. Poor sensitivities (47% to 49%) limited the detection of abnormal findings by the screen; both screens were reasonably specific (79% to 89%), but negative predictive values were suitable (89%) for serum bilirubin results only and were prohibitively lower (49% to 50%) in predicting all patients without LFT abnormalities. We conclude that spot urine urobilinogen and urine bilirubin determinations, although good screens for isolated serum bilirubin elevations, have unacceptable statistical properties as predictors of other LFT results due to a high proportion of false-negative results.

Bilirubin↗
PubMed1989

Implementing differentiated practice: the Sioux Valley Hospital experience.

Historically, nurses with different levels of education have been used interchangeably in acute care hospitals. If nursing is going to be viewed as a preferred career choice and acute care hospitals are to retain staff, nurse administrators must provide a nursing practice model that differentiates scope of practice based on education. The authors discuss how they implemented a system of differentiated practice.

Costs and Cost Analysis↗
PubMed1988

Comparative, multicenter studies of cefixime and amoxicillin in the treatment of respiratory tract infections.

A total of 560 patients were treated in two double-blind, randomized multicenter studies to compare the safety and efficacy of cefixime (400 mg administered once daily) and amoxicillin (250 or 500 mg administered three times daily) for the treatment of bacterial respiratory tract infections. Eighty percent of the 244 patients treated in the lower respiratory tract infections (LRTI) study had acute bronchitis. Streptococcus pneumoniae (13 percent), Haemophilus influenzae (28 percent), and Escherichia coli (10 percent) were the pathogens most frequently isolated from sputum in these patients. Among evaluable patients with positive bacterial culture results at baseline, a favorable clinical response (cured or improved) was obtained in 100 percent of the cefixime-treated patients (22 of 22) and in 96 percent of the amoxicillin-treated patients (23 of 24). Bacteriologic eradication rates were 100 percent and 83 percent for cefixime and amoxicillin, respectively. In the upper respiratory tract infections (URTI) study, 316 patients with pharyngitis (80 percent) or tonsillitis (14 percent) were treated. Group A, beta-hemolytic Streptococcus (69 percent) and H. influenzae (8 percent) were the pathogens most frequently isolated from the throat culture specimens of these patients. Favorable clinical results were obtained in 99 percent of the evaluable cefixime-treated group (n = 73) and in 98 percent of the amoxicillin-treated group (n = 66). The bacteriologic eradication rates were 93 percent and 100 percent, respectively. The adverse experiences reported during both studies were similar in nature and frequency to those reported for other beta-lactam antibiotics with the exception of a higher incidence of altered bowel movement (diarrhea and stool changes) with both drugs. These episodes usually resolved without remedial medication when the treatment was withdrawn. No significant adverse laboratory findings were observed. Results of these trials demonstrate that cefixime at a dosage of 400 mg once daily is an effective and safe oral antibiotic for the treatment of acute respiratory tract infections.

Amoxicillin↗