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Biomedical subjects

B Nelson

Publications and source records attributed to B Nelson.

At least 37 records · Page 2Linked to original sources
PubMed1998

Evaluation of the effects of brushing on the removal of dental plaque.

The ability of three different toothpaste abrasive systems--sodium bicarbonate, hydrated silica, and dicalcium phosphate--to remove dental plaque has been examined. A total of 34 volunteers participated in an independent, double-blind, crossover clinical investigation that compared the amount and percentage of plaque removed with a single brushing with Arm & Hammer Dental Care (sodium bicarbonate), Crest Regular Toothpaste (hydrated silica), and Colgate Regular Toothpaste (dicalcium phosphate) after 48 hours of limited oral hygiene. All three dentifrices removed from 58% to 68% of plaque, but the percentage removed after brushing with Arm & Hammer Dental Care was significantly greater than with either Crest (p = 0.0001) or Colgate (p = 0.0002) during a controlled, 1-minute toothbrushing. The mean amount of plaque removed with Arm & Hammer Dental Care was also significantly greater than that with Crest or Colgate (p = 0.0002 and p = 0.0004, respectively). These results indicate that the abrasive system in Arm & Hammer Dental Care was the most efficient in removing plaque and improving oral hygiene. In the second half of the study, Arm & Hammer Dental Care was compared with Arm & Hammer Peroxicare and Mentadent toothpaste in 45 subjects. All three dentifrices removed from 57% to 70% of the plaque, with Arm & Hammer Dental Care removing significantly more than Mentadent (p = 0.007).

Adolescent↗
PubMed1997

The corticotropin-releasing hormone challenge in depressed abused, depressed nonabused, and normal control children.

Hypothalamic-pituitary-adrenal (HPA) axis disturbances in depressed children with a history of abuse were examined. Thirteen depressed abused, 13 depressed nonabused, and 13 normal control children were given 1.0 microgram/kg of human corticotropin-releasing hormone (CRH) intravenously. Blood samples for corticotropin (ACTH) and cortisol were obtained at nine intervals. When compared to depressed nonabused and normal control children, depressed abused children had significantly greater peak, total, and net ACTH secretion post-CRH. Increased ACTH secretion was only observed in depressed abused children experiencing ongoing chronic adversity (marital violence, emotional abuse, poverty, lack of supports). The pattern of findings of the depressed abused children experiencing ongoing adversity parallels the pattern of HPA axis dysregulation reported in animal studies of chronic stress. They add to a growing body of literature suggesting measures of past trauma and current adversity are important sources of variability in psychobiological correlates of major depression.

Adolescent↗
PubMed1997

Neuroendocrine response to 5-hydroxy-L-tryptophan in prepubertal children at high risk of major depressive disorder.

BACKGROUND: Altered serotonergic function has been observed in prepubertal children and adults with an acute episode of major depressive disorder (MDD). However, it is not known whether these alterations are present prior to the onset of MDD. METHODS: A serotonergic precursor, 5-hydroxy-L-tryptophan (L-5HTP) (oxitriptan) (0.8 mg/kg), was administered through an indwelling catheter to 36 children at high risk of MDD (with high family loading for MDD), 31 children with MDD, and 23 low-risk normal controls (with low family loading for mood disorders and no history of psychopathology). Blood samples for cortisol, prolactin (PRL), and growth hormone were obtained every 15 minutes for 180 minutes, beginning 30 minutes before L-5HTP infusion. RESULTS: Children at high risk of MDD and children with MDD had similar hormonal responses following L-5HTP infusion. After controlling for baseline values, both groups secreted significantly less cortisol and more PRL than did the low-risk normal controls, with the PRL finding being limited to girls. There were no between-group differences in baseline cortisol, PRL, or growth hormone secretion measures. CONCLUSIONS: Before the onset of affective illness, high-risk children had the same pattern of neuroendocrine response to the L-5HTP challenge as did children with MDD. These results extend earlier findings of altered serotonergic regulation in association with early-onset depression and indicate that these alterations may represent a trait marker for depression in children.

5-Hydroxytryptophan↗
PubMed1997

Evaluating the decay gradient for collinearity bias with lateral displacement from the axis of induction.

The misperception of alignment which is found in many geometric illusions can be quantified using relatively simple stimulus configurations. Perceived collinearity of one segment (designated as the test segment) is biased by a second segment (designated as the induction segment), with the size of effect being a function of the relative angle between the two segments. The process can be described as angular induction. The strength of bias is greatest when the induction segment is centered at the tip of the test segment. Tong and Weintraub have reported that lateral displacement from the tip, i.e., at right angles to the axis of the induction segment, produces a sharp drop in the strength of effect. This decline is described as a "decay gradient" for the angular induction. One experiment replicates and provides better quantification of this "decay gradient". Two other experiments examine the decay gradient using a pair of induction segments, one on each side of the tip of the test segment. Displacement of the segments (either in the same direction or in opposite directions) produces substantially the same gradient of effect. Therefore, previous evidence of "tandem boosting" of effect for segment pairs does not depend on collinearity among the stimulus components. Finally, a fourth experiment finds that an induction segment which is at a fixed position and orientation differentially affects the influence of a variable induction segment. At some angles the influence of the variable segment is augmented, and at others it is suppressed. These findings are discussed in a neuroreductionist context, and a simple model for angular induction is presented.

Analysis of Variance↗
PubMed1997

Follicular mucinosis associated with scarring alopecia, oligoclonal T-cell receptor V beta expansion, and Staphylococcus aureus: when does follicular mucinosis become mycosis fungoides?

A diagnosis of alopecia mucinosa, occurring as a single scalp lesion, was made in a 40-year-old white woman who had a history of trauma. Follicular mucinosis, Staphylococcus aureus, and oligoclonal expansion of the T-cell receptor V beta chain genes 6 and 7 were present in the skin. Epidermotropic T-cell skin diseases with oligoclonal T-cell proliferations may be the result of HLA- and cytokine-determined reaction patterns to persistent antigens.

Adult↗
PubMed1997

Effects of choosing academic assignments on a student with attention deficit hyperactivity disorder.

The effects of choosing academic assignments on the undesirable behaviors manifested by a second-grade student with attention deficit hyperactivity disorder were analyzed. This study extended Dunlap et al.'s (1994) research on choice making as a form of antecedent control. A reversal design showed that undesirable behaviors decreased when the student was given a choice of academic assignments.

Attention↗
PubMed1997

Evaluating Müller-Lyer effects using single fin-set configurations.

Four experiments were conducted to study the bias of perceived length for Müller-Lyer configurations that contained a single set of fins (i.e., two segments that join to form a vertex). The experiments manipulated several factors that have been shown to be critical to the effect: (1) version (which way the apex pointed), (2) length of the stimulus span, (3) presence or absence of a line segment in the span being judged, (4) fin length, (5) fin angle, and (6) the zone in which the response was rendered. Using percent error as the index of perceptual distortion, the major finding was that the two versions show an opposite slope for strength of effect as a function of span. When stimulus spans were plotted against response means (not converting to percent error), an almost perfect linear relation was found. These results indicate that the perceptual effects can be modeled as a linear system having two parameters through which the treatments exert their influence. The results are discussed in relation to major theories of mechanism for the Müller-Lyer illusion.

Adult↗
PubMed1996

The relationship between longitudinal clinical course and sleep and cortisol changes in adolescent depression.

This study examined the relationship between longitudinal clinical course and sleep and cortisol findings in adolescent unipolar major depressive disorder (MDD). Subjects were 28 adolescents (15.4 +/- 1.3 years) systematically diagnosed with unipolar MDD and 35 group-matched normal controls who participated in EEG sleep and neuroendocrine studies. Follow-up clinical assessments were conducted 7.0 +/- 0.5 years later in 94% of the original cohort. Although initial group comparisons failed to show significant differences in biologic measures, analyses incorporating clinical follow-up reveal that changes in sleep and cortisol measures are associated with differential longitudinal course. Normal controls who would develop depression after the biologic studies had shown significantly higher density of rapid eye movements (REM) and a trend for reduced REM latency compared to controls with no psychiatric disorder at follow-up. Depressed subjects with a recurrent unipolar course showed a trend towards elevated plasma cortisol near sleep onset compared to MDD subjects with no further episodes during the follow-up interval.

Adolescent↗
PubMed1996

Corticotropin-releasing hormone challenge in prepubertal major depression.

This study investigates cortisol and ACTH (corticotropin) responses to an infusion of human CRH (corticotropin-releasing hormone) in prepubertal children with major depressive disorder (MDD). Following a period of 24 hours of adaptation to the laboratory environment with an intravenous catheter in place, 34 children with MDD and 22 healthy controls received 1 microgram/kg of human CRH at 5:00 PM. Blood samples for cortisol and ACTH were measured at baseline and post-CRH. Overall, there were no significant differences between the MDD and the normal controls in baseline or post CRH stimulation values of either cortisol or ACTH. Melancholic (n = 4) patients had significantly higher baseline cortisol levels than nonmelancholic (n = 24) patients. Compared with the outpatients and the nonmelancholics, the inpatients (n = 10) and the melancholics showed significantly lower total ACTH secretion (effect size: 0.9 and 1.4, respectively) after CRH infusion. These results are consistent with a broad literature suggesting that the HPA axis abnormalities occur less frequently in early-onset depression than reported in adult studies. The pattern of results in the subgroups of inpatients and in melancholic children, however, raise questions about possible continuities with adult studies.

Adolescent↗
PubMed1996

A double-blind, placebo-controlled study of anti-CD5 immunoconjugate in patients with rheumatoid arthritis. The Xoma RA Investigator Group.

OBJECTIVE: To evaluate the efficacy of an anti-CD5 ricin-linked immunoconjugate (CD5-IC) in patients with rheumatoid arthritis (RA). METHODS: A total of 104 evaluable patients were enrolled in a multicenter, double-blind, multiple-dose, placebo-controlled study of CD5-IC. RESULTS: Treatment with CD5-IC in doses up to 8 mg/m2/day for 4 days in 1 month failed to produce marked or prolonged T cell depletion and was no more effective than placebo in ameliorating disease manifestations. An unexpectedly high placebo response was observed in 48% of the patients. Adverse events were correlated with the dose of CD5-IC, but the treatment was generally well-tolerated. CONCLUSION: At the doses used in this study, CD5-IC was ineffective for treating RA.

Adult↗
PubMed1996

Nocturnal ACTH, cortisol, growth hormone, and prolactin secretion in prepubertal depression.

OBJECTIVE: To examine nocturnal secretion of adrenocorticotropin, cortisol, growth hormone, and prolactin in 38 medically healthy children with prepubertal major depression compared with 28 medically and psychiatrically healthy control children. METHOD: Prior to sampling, subjects underwent an "adaptation night" with the intravenous catheter in place and electroencephalographic (EEG) electrodes for standard all-night polysomnogram. On the following night, plasma samples were obtained every 20 minutes through an indwelling catheter. Hormonal concentrations were measured by specific radioimmunoassay and aligned by EEG-confirmed sleep onset. Areas under the curve were calculated for total secretion and compared using analysis of variance. RESULTS: Prepubertal depressed children had lower cortisol secretion during the first 4 hours after sleep onset compared with controls. Adrenocorticotropin, prolactin, and growth hormone secretion did not differ between groups. Examination of clinical characteristics in depressed children revealed lower nocturnal adrenocorticotropin concentrations in depressed inpatients versus depressed outpatients and in depressed sexually abused versus depressed nonabused children. A significant sex by diagnosis effect revealed lower growth hormone secretion in depressed females compared with depressed males. CONCLUSIONS: In contrast to neuroendocrine challenge studies in these same subjects, nocturnal neuroendocrine measures did not reveal any of the expected group differences. These results emphasize the contrasts between unstimulated and challenge studies of neuroendocrine secretion and of the importance of considering clinical characteristics and maturation influences in biological studies of prepubertal depression.

Adolescent↗
PubMed1996

Childhood and adolescent depression: a review of the past 10 years. Part I.

OBJECTIVE: To qualitatively review the literature of the past decade covering the epidemiology, clinical characteristics, natural course, biology, and other correlates of early-onset major depressive disorder (MDD) and dysthymic disorder (DD). METHOD: A computerized search for articles published during the past 10 years was made and selected studies are presented. RESULTS: Early-onset MDD and DD are frequent, recurrent, and familial disorders that tend to continue into adulthood, and they are frequently accompanied by other psychiatric disorders. These disorders are usually associated with poor psychosocial and academic outcome and increased risk for substance abuse, bipolar disorder, and suicide. In addition, DD increases the risk for MDD. There is a secular increase in the prevalence of MDD, and it appears that MDD is occurring at an earlier age in successive cohorts. Several genetic, familial, demographic, psychosocial, cognitive, and biological correlates of onset and course of early-onset depression have been identified. Few studies, however, have examined the combined effects of these correlates. CONCLUSIONS: Considerable advances have been made in our knowledge of early-onset depression. Nevertheless, further research is needed in understanding the pathogenesis of childhood mood disorders. Toward this end, studies aimed at elucidating mechanisms and interrelationships among the different domains of risk factors are needed.

Adolescent↗
PubMed1996

Management of back pain in athletes.

Back pain affects millions of people. It affects 80% of the population and up to 52% at any given time. Back pain is not limited to sedentary individuals; it has significant effects on athletes as well. Depending upon the sport, incidence rates of back pain occur in athletes from 1.1% to as high as 30%. Athletes differ from the non-athletic population in that their incentives to return to activity are considerably different than non-athletes. The reasons may vary from the will to win through to significant financial considerations. Although reasons for recovery are different, the physiology and mechanics of repair of injured soft tissue in the athlete is the same as for the non-athlete. Proper management of the athlete requires ruling out emergent causes of back pain such as tumour, infection, acute fracture, progressive neurological deficit, visceral sources (e.g. pancreatitis, abdominal aortic aneurysm), and rheumatoid variants. Once a good history and physical is performed, a simple classification system can be utilised to manage the athlete presenting with back pain. This system can be expressed as: (a) regional back pain; (b) radicular leg pain; (c) radicular leg pain with progressive neurological deficit; and (d) cauda equina syndrome. Each of these categories needs to be managed in a specific manner and can provide the healthcare professional with simple, straightforward guidelines for handling the athlete with lower back pain. The key is to return the athlete to the field of play in a safe and timely manner.

Athletic Injuries↗
PubMed1995

Stressful life events and EEG sleep in depressed and normal control adolescents.

EEG sleep measures in 35 depressed and 33 normal control adolescents were examined in relation to stressful life events occurring in the year before sleep studies. There was a significant interaction between stressful life events and diagnostic status for REM latency and total REM time. In the normal controls, the presence of stressful life events was significantly associated with reduced REM latency and increased total REM time. Among the depressed adolescents, there were no significant effects of stressful life events on REM latency or total REM time. The depressed adolescents with no stressful life events (n = 9) had significantly lower REM latency values compared to normal control adolescents with no stressful life events (n = 13)(61.7 +/- 50.0 vs. 132.1 +/- 79.0, p < or = .01). It appears that stressful life events influence at least some measures of adolescent sleep and should be considered in future controlled studies aimed at understanding sleep changes in adolescent depression.

Adolescent↗
PubMed1995

Unipolar depression in adolescents: clinical outcome in adulthood.

OBJECTIVE: This study examined the longitudinal clinical course and adult sequelae of adolescent unipolar major depressive disorder (MDD) using a controlled longitudinal design. METHOD: Subjects were 28 adolescents (15.4 +/- 1.3 years) with systematically diagnosed unipolar MDD and 35 group-matched control subjects who participated in a cross-sectional electroencephalogram sleep and neuroendocrine study. Using standardized instruments, interviewers who were blind to subjects' initial diagnoses conducted follow-up clinical assessments 7.0 +/- 0.5 years later in 94% of the original cohort. RESULTS: The depressed group showed high rates of recurrence of MDD episodes during the interval period (69%). They also had elevated rates of new-onset bipolar disorder (19%). Twenty-three percent of subjects with an initial diagnosis of MDD had no additional depressive episodes after the index assessment. The rate of new onset of depression in the controls was 21%. Low socioeconomic status predicted recurrence of depressive episodes in the MDD group. MDD subjects with recurrence(s) and controls with new onset of depression during the follow-up period had significant psychosocial morbidity, as evidenced by disruption in interpersonal relationships and dissatisfaction with life and decrease in global functioning, compared with both MDD subjects with no further episodes and control subjects who had never been psychiatrically ill. These psychosocial deficits persisted remission from depressive episode(s). CONCLUSIONS: Adolescent unipolar MDD predicts continued risk for recurrences with persistence of depressive episodes and psychosocial morbidity into adulthood. A sizable minority, however, have sustained periods of remission associated with good social adjustment.

Adolescent↗