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Biomedical subjects

R T Brown

Publications and source records attributed to R T Brown.

At least 19 recordsLinked to original sources
PubMed1992

Chemotherapy for acute lymphocytic leukemia: cognitive and academic sequelae.

Iatrogenic cognitive impairments have been reported for survivors of childhood leukemia after prophylactic central nervous system therapy with craniospinal radiation. To determine whether chemotherapy alone might be a source of central nervous system damage, we assessed in a cross-sectional design the cognitive and academic functioning of 48 children with acute lymphocytic leukemia who were at various stages in their treatment or who had completed treatment. The off-therapy patients who had completed a 3-year course of chemotherapy were more impaired in tasks of higher-order cognitive functioning than were those children whose leukemia had been newly diagnosed and those children whose diagnoses had been 1 year earlier. Off-therapy patients also had concomitant diagnosable learning disabilities in mathematics. We recommend appropriate liaison and special education placements, as well as continued evaluation of cognitive and leaning functioning of children treated for moderate-risk acute lymphocytic leukemia who receive chemotherapy alone.

Achievement↗
PubMed1992

Psychiatric and family functioning in children with leukemia and their parents.

The present study reports data from a cross-sectional investigation of the psychiatric and psychosocial functioning of 55 children diagnosed with acute lymphocytic leukemia and their families at three points in time: diagnosis (newly diagnosed), 1 year postdiagnosis, and 1 year after the completion of chemotherapy (off-therapy). Results reveal minimal psychopathology in these children and their parents based on self- and informant-reports and structured diagnostic interviews. These families appear to be functioning adequately and report more family cohesiveness and marital satisfaction after chemotherapy was completed. Coping strategies commonly used by children and their parents include problem-solving, a positive outlook, and good communication. Implications for psychiatric consultation are presented.

Adaptation, Psychological↗
PubMed1992

Compliance with breast self-examination instruction in high school students.

In a prospective study, we measured compliance with breast self-examination, using an anonymous questionnaire, in suburban high school students three months (n = 85) and eight months (n = 54) after group instruction. Post-instruction proficiency in performing the procedure and personal health beliefs regarding breast cancer were also evaluated. At three months, 40% of the group reported practicing breast self-examination at some time since instruction; 12% had performed the procedure timed correctly with their menstrual cycle. At eight months, only two girls (4%) had practiced breast self-examination at least once since the three-month evaluation. Proficiency scores overall were high, with 77% scoring 12 points or above on a 15-item questionnaire; however, scores were significantly lower in the 15-year-olds than in the older adolescents. No significant relationships were found between compliance and most personal health beliefs, previous instruction, or level of knowledge of the procedure. Attention should be directed toward assessing the ability and willingness to practice preventive health behaviors before instruction programs are instituted in this age group.

Adolescent↗
PubMed1992

Update on pregnancy, condom use, and prevalence of selected sexually transmitted diseases in adolescents.

Adolescent pregnancy and its consequences continue as major sources of morbidity in the United States. A teenager who becomes a parent is at a significant disadvantage in becoming a contributing adult, both psychosocially and economically. The physician who cares for adolescents has the responsibility of helping parenting teens to find needed support so that they will be able to overcome this significant hurdle. Attention from public agencies has focused on increasing condom use as one approach to adolescent pregnancy prevention. The major advantage of using condoms is that they also prevent transmission of sexually transmitted diseases. Of note is that level of knowledge about condoms is not related to their use, and engaging in high-risk behaviors is related to a decreased likelihood of condom use. With rates of condom use estimated at less than 50%, rates of sexually transmitted disease remain high, as reported in recent surveys.

Adolescent↗
PubMed1992

A comparison of never-hospitalized and previously hospitalized adolescents: self-esteem and locus of control.

Few empirical studies have been conducted to determine the influence of hospitalization on adolescents' psychosocial processes because younger children are regarded as more vulnerable. Therefore, the purpose of this self-report, retrospective study of 115 adolescents was to compare the self-esteem and locus of control of the never hospitalized to that of adolescents hospitalized during adolescence, prior to adolescence, and during and prior to adolescence. Although no significant differences were found, the findings raise questions about long-term effects of early experiences, especially among lower socioeconomic status youth. Also, general measures of self-esteem and locus of control may be unable to determine situation-specific effects.

Adolescent↗
PubMed1992

Adolescent sexuality and issues in contraception.

The influence of physiologic, psychologic, and cultural influences on human sexuality is reviewed. These factors are considered in the exploration of how adolescents express their sexuality and the consequences of that expression.

Adolescent↗
PubMed1991

Gender differences in a clinic-referred sample of attention-deficit-disordered children.

This study of attention-deficit-disordered children revealed that females were more frequently retained in school and evidenced greater impairment on spatial memory tasks. Moreover, there was a trend for girls to be older at the time of referral. With age, the girls evidenced more severity across a wider array of measures, including cognitive functioning, poorer academic achievement, and more problems with peers.

Achievement↗
PubMed1991

Computed tomography, magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose in multiple system atrophy and pure autonomic failure.

We studied 45 patients who had autonomic failure with computed tomography, magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose to characterize the neuroimaging features of multiple system atrophy and pure autonomic failure and determine the utility of these techniques in distinguishing multiple system atrophy from pure autonomic failure. There were 30 patients with multiple system atrophy and 15 with pure autonomic failure. In the multiple system atrophy group, eight patients had mainly cerebellar signs, seven extrapyramidal and 15 had combinations of cerebellar and extrapyramidal signs. Cerebellar atrophy on computerized tomography and magnetic resonance imaging, signal hypointensity in the posterolateral putamen on magnetic resonance imaging and a generalized reduction in glucose utilization rate with positron emission tomography with [18F]fluorodeoxyglucose, were the main findings and were seen only in the patients with multiple system atrophy. Decreased glucose utilization (hypometabolism) was most prominent in the cerebellum, brainstem, striatum and frontal and motor cortices. These results indicate clear differences, using neuroimaging studies, between multiple system atrophy and pure autonomic failure.

Atrophy↗
PubMed1991

Internalizing and externalizing symptoms and attributional style in youth with diabetes.

The psychiatric functioning of 28 youths with insulin-dependent diabetes mellitus was examined. Measures of psychological functioning were related to age at onset, duration of diabetes, and metabolic control, as assessed by HgbAlC. Children diagnosed with insulin-dependent diabetes mellitus at a later age were considered by teachers to have more behavioral problems. Children who had better metabolic control tended to hold themselves responsible for negative events. It is worthwhile to develop interventions to teach diabetic children a realistic balance between taking appropriate responsibility for controllable negative events without taking undue blame for uncontrollable negative events associated with the disease.

Adaptation, Psychological↗
PubMed1991

Central and peripheral effects of arecoline in patients with autonomic failure.

Increased plasma adrenalin (A) levels following arecoline in normal subjects and patients with multiple system atrophy (MSA) may result from nicotinic adrenal stimulation. Lack of this response in patients with pure autonomic failure (PAF) is consistent with peripheral sympathetic dysfunction. The mechanisms underlying diminished plasma corticotropin (ACTH) responses to arecoline may differ in patients with autonomic failure. Hypothalamic, cholinergic degeneration could prevent the response in MSA whereas patients with PAF do not manifest the normal increase in A which may be required to elicit an ACTH response. The appearance and exacerbation of tremor, vertigo, and pathological affect in the MSA group suggest that some central cholinergic receptors remain functional.

Adrenocorticotropic Hormone↗
PubMed1991

Beta-receptor sensitivity in autonomic failure.

We examined the cardiovascular, plasma norepinephrine (NE), and plasma renin (PRA) responses to isoproterenol infusion in patients with autonomic failure and in normal subjects. Slopes of the blood pressure response/dose relationships were more negative in patients with multiple system atrophy and pure autonomic failure (PAF) than in normal subjects, consistent with impaired baroreflex modulation. A shift to the left in patients with PAF suggests beta-adrenergic receptor supersensitivity. In normal subjects, the increase in plasma NE and PRA was proportional to the log of the plasma isoproterenol level. Isoproterenol infusion did not increase plasma NE or PRA in either patient group despite a reduction in mean blood pressure. Reflexive cardiovascular and renal mechanisms appear to play a role in eliciting the plasma NE and PRA responses to isoproterenol infusion in normal subjects.

Autonomic Nervous System Diseases↗
PubMed1979

Quantitative relationships of the ototoxic interaction of kanamycin and ethacrynic acid.

We determined the range of doses of kanamycin sulfate and ethacrynic acid that results in an ototoxic interaction in guinea pigs. In addition, we determined the time interval between the administration of the two drugs that is needed to produce this interaction. In all cases, the magnitude of the ototoxic lesion was determined by measuring the cochlea's ability to generate both the sensitivity and intensity functions of the ac cochlear potential. In addition, the cochlear pathologic conditions, as determined by counting the number of missing hair cells in the organ of Corti, was found to correlate highly with the ac cochlear potential data. The dosage range of ethacrynic acid during which the interaction occurs is very narrow, while the dose range of kanamycin is very large.

Animals↗
PubMed1979

Methylphenidate in hyperkinetic children: differences in dose effects on impulsive behavior.

This research tested the hypothesis that in hyperactive children a low dose of methylphenidate (0.3 mg/kg) would produce scores superior to those with a high dose (1.0 mg/kg) or placebo on the matching familiar figures test (MFF), a primary index of impulsivity. The hypothesis was based on an earlier finding that the highest percentage of correct responses on a short-term memory task were found in hyperactive subjects who were receiving 0.3 mg/kg of methylphenidate whereas at 1.0 mg/kg the percentage correct returned to the placebo level. The hypothesis was verified in that the low dose reduced the number of errors on the MFF significantly more than did placebo or the high dose. This work demonstrates that, for both learning and impulsivity in hyperactive children, the lower dose of the two doses of methylphenidate studied produced the preferable effect.

Adolescent↗
PubMed1978

Comparative ototoxic liability of netilmicin and gentamicin.

Netilmicin sulfate is a new aminoglycoside antibiotic currently undergoing clinical investigation. All of the aminoglycoside antibiotics now in clinical use are ototoxic. This study was done to determine the ototoxic liability of netilmicin when it is compared directly with gentamicin sulfate. Groups of ten guinea pigs each were given doses of 0, 50, 100, or 150 mg/kg of either gentamicin or netilmicin daily for four weeks. After a two-week stabilization period, the Preyer pinna reflex, the cochlea's ability to generate the ac cochlear potential, and the missing hair cells from the cochleas were determined. Additionally, the pharmacokinetics of both drugs in the plasma and perilymph were determined. Little or no cochlear damage was detected with netilmicin, even at the highest dose, while even the smallest dose of gentamicin produced measurable changes in cochlear function.

Acoustic Stimulation↗