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Biomedical subjects

R T Brown

Publications and source records attributed to R T Brown.

At least 91 records · Page 5Linked to original sources
PubMed1988

Low lumbar CSF levels of homovanillic acid and 5-hydroxyindoleacetic acid in multiple system atrophy with autonomic failure.

Low lumbar CSF concentrations of homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in patients with multiple system atrophy attended by autonomic failure (MSA) reflect decreased activity in central dopaminergic and serotonergic pathways. These neurochemical changes are consistent with the neuropathological involvement in MSA and distinguish such patients from those with pure autonomic failure who have normal CSF metabolite levels.

Adult↗
PubMed1988

A controlled trial of methylphenidate in black adolescents. Attentional, behavioral, and physiological effects.

The short-term effects of methylphenidate were examined on behavioral, laboratory, academic, and physiological measures in 11 black male adolescents diagnosed as having attention deficit disorder (ADD). In a double-blind, crossover design with randomized order, the subjects received placebo and each of three methylphenidate doses (0.15 mg/kg, 0.30 mg/kg, and 0.50 mg/kg) for a period of 2 weeks per medication dosage. Significant drug effects were found for the majority of measures. In general, the higher doses resulted in the most beneficial response in behavioral, academic, and laboratory measures of attention and impulsivity. However, a significant linear increase occurred in diastolic blood pressure. The results suggest that methylphenidate is an effective adjunct to the treatment of ADD in adolescents.

Adolescent↗
PubMed1987

Beta-endorphin, ACTH, and catecholamine responses in chronic autonomic failure.

Plasma epinephrine (EPI), norepinephrine (NE), beta-endorphin, and corticotropin (ACTH) responses were measured during insulin-induced hypoglycemia in normal subjects and in patients with either multiple system atrophy (MSA) or idiopathic orthostatic hypotension (IOH). In normal subjects, there was a striking rise in EPI, NE, beta-endorphin, and ACTH following the nadir of hypoglycemia. Both beta-endorphin and ACTH responses were significantly lower than normal in patients with MSA, in contrast to normal levels in IOH patients. No correlation was observed between the degree of adrenergic insufficiency and the beta-endorphin and ACTH responses. The normal peptide responses in IOH are consistent with involvement limited to the peripheral sympathetic nervous system, whereas lesions in the central nervous system in MSA interfere with release of beta-endorphin and ACTH in response to hypoglycemia. The strong correlation between beta-endorphin and ACTH levels is consistent with their common origin. Peripheral adrenergic activity is not essential for beta-endorphin and ACTH release in humans.

Adrenal Glands↗
PubMed1987

Hallucinogens.

This article describes the various hallucinogens with which adolescents may come in contact. Perspective is provided as to the importance of the various hallucinogens and to their effects on adolescent users.

Adolescent↗
PubMed1987

Piagetian conservation and response to cognitive therapy in attention deficit disordered children.

Cognitive therapy is often used in treating attention-deficit-disordered (ADD) children because of its purported ability to address this population's attentional deficits and behavioral difficulties and to create durable therapeutic effects. Nonetheless, research findings on these treatments have been inconsistent. This study sought to explain these inconsistencies by examining the influence of cognitive development on children's ability to benefit from such treatment. The ability to conserve number and substance was shown to influence treatment outcome, as measured by laboratory tasks of cognitive style and impulsivity. No effects were found on standardized academic achievement measures or on behavioral ratings by teachers or parents. Further study of individual development will be important in understanding the outcomes of cognitive therapy.

Attention↗
PubMed1987

Dominantly inherited Alzheimer's disease: cerebral glucose metabolism.

Cerebral glucose metabolic rate (CMRGlu), measured by positron emission tomography, was bilaterally and symmetrically reduced in two patients with autosomal dominant Alzheimer's disease. Supramarginal gyri and temporal lobes were most severely affected. An isolated reduction of CMRGlu in the left supramarginal gyrus was observed in one asymptomatic at-risk subject.

Adult↗
PubMed1987

MRI in autonomic failure.

A significant rank correlation between rigidity and putaminal signal dropout on magnetic resonance imaging (MRI) in patients with multiple system atrophy suggests that putaminal degeneration may cause this clinical finding. Absence of putaminal abnormalities on MRI in patients with pure autonomic failure may prove useful in differentiating these two autonomic disorders.

Aged↗
PubMed1987

Adrenergic dysfunction in hereditary adult-onset leukodystrophy.

We studied the pressor response to norepinephrine infusion in patients with an autosomal dominant adult-onset leukodystrophy. We also examined cardiovascular and catecholamine responses to insulin-induced hypoglycemia. A parallel shift to the left of the norepinephrine dose response curve, in conjunction with low baseline plasma norepinephrine levels, was consistent with denervation supersensitivity, suggesting a distal lesion of sympathetic noradrenergic neurons. Absence of the epinephrine response to insulin-induced hypoglycemia indicated that autonomic neuropathy was attended by severe adrenal medullary dysfunction.

Adult↗
PubMed1987

Interconversion of O-methylated norepinephrine metabolites in humans.

Levo-norepinephrine labeled with tritium was used to study urinary norepinephrine metabolites as an index of whole body norepinephrine turnover. Six healthy volunteers were given intravenous infusions of [ring-2,5,6-3H] levo-norepinephrine, followed by collection of urine for 24 hours. Specific activities were determined by high-performance liquid chromatography for each of the three O-methylated metabolites of norepinephrine in the urine samples, and were then used to calculate the fraction of 4-hydroxy-3-methoxymandelic acid (VMA) formed from 4-hydroxy-3-methoxyphenylglycol (MHPG) and from normetanephrine. These values were used, in conjunction with total excretion of each of these metabolites, to calculate the fraction of MHPG and normetanephrine converted to VMA. The fraction of VMA formed from MHPG was 0.821 +/- 0.020, and that from normetanephrine was 0.179 +/- 0.020. Whereas fractional conversion of normetanephrine to VMA was 0.634 +/- 0.030, that of MHPG to VMA was only 0.507 +/- 0.025. Similar results were obtained when the experiment was repeated in three of the subjects using [8-14C] levo-norepinephrine, suggesting that isotope, specific activity, and position of the label were not determinants of the values obtained. The present results confirm the extent of conversion of MHPG to VMA described by others, and suggest that a higher percentage of normetanephrine than previously reported is converted to VMA.

Adult↗
PubMed1987

Treating the adolescent: the initial meeting.

In this article, we have tried to point out ways in which the initial interview can be facilitated, and in which it can be made to be both a pleasant and informative experience for the adolescent patients, and a productive and enjoyable encounter for the practitioner. The major areas include appropriate attitudes of personnel and the physical environment in which the patient is seen; the way in which a physician can introduce him- or herself to the family; methods of obtaining information from adolescent patients; differences of which one should be aware when interviewing adolescent patients at different developmental levels; and ways in which to establish rapport and to approach especially sensitive issues. Techniques to reduce anxiety in the physical examination and how to conclude the encounter are also reviewed. By using some of the techniques discussed for the initial encounter, and by incorporating those into his or her own style, the ability to care for adolescent patients can be enhance so that the physician can enjoy and, therefore, be willing to address effectively the health needs of adolescent patients.

Adolescent↗
PubMed1986

Methylphenidate and cognitive therapy with ADD children: a methodological reconsideration.

The present double-blind study examined the effects of methylphenidate, cognitive therapy, and their combination in attention deficit-disordered (ADD) children. Four treatment groups were compared on measures of attentional deployment and cognitive style, tests of academic achievement, and behavioral rating scales. In contrast to a previous study conducted in this laboratory, children in this study were not receiving medication during post-testing. Results were interpreted to suggest that measurable effects of stimulant medication dissipate rapidly upon discontinuation of pharmacotherapy. The combination of methylphenidate and cognitive therapy was not found to be any more efficacious than either of the treatments studied alone. Discussion suggests that medication status at follow-up is an essential feature of research design.

Achievement↗
PubMed1986

Insulin-induced hypotension and neurogenic orthostatic hypotension.

Insulin-induced hypoglycemia induced a fall in blood pressure (BP) in patients with idiopathic orthostatic hypotension (IOH) and multiple system atrophy (MSA), but not in control subjects. Only in IOH was there a correlation between plasma norepinephrine (NE) levels and maintenance of BP during the test. The hypotension was not affected by pretreatment with propranolol. Hypotension during insulin-induced hypoglycemia is manifested in patients who lack an adequate NE response. The hypotension, however, may be due to a central action of insulin because not all MSA patients with impaired NE release become hypotensive.

Aged↗
PubMed1986

Methylphenidate and cognitive therapy in children with attention deficit disorder: a double-blind trial.

Stimulant medications have been the treatment of choice for children with Attention Deficit Disorder (ADD), yet long-term benefits have not been found. The present study examined the ability of an adjunctive cognitive behavioral self-control therapy program to improve upon these long-term results. Findings only partially supported the efficacy of the cognitive therapy, as demonstrated on the Matching Familiar Figures Test of impulsivity. However, this improvement did not persist over time. Results are discussed in terms of the need for pediatricians to consider individual differences in therapeutic response across patients.

Adolescent↗
PubMed1985

Decreased sympathetic neuronal uptake in idiopathic orthostatic hypotension.

The disappearance rates from plasma of intravenously administered levo-norepinephrine (l-NE), dextro-norepinephrine (d-NE), and isoproterenol (ISO) were measured in normal subjects and in patients with either multiple-system atrophy (MSA) or idiopathic orthostatic hypotension (IOH). The two isomers, l-NE and d-NE, were removed at similar rates in all groups. In normal subjects, the d and l isomers of norepinephrine were cleared more rapidly than ISO. In patients with IOH, the initial rates of disappearance of the NE isomers from plasma were slower than normal and similar to the rate for ISO disappearance. Plasma NE levels, NE clearance, and the apparent release rate of NE into plasma from sympathetic neurons were significantly lower in patients with IOH than in normal subjects. Only the apparent NE secretion rate was related to the baseline plasma NE level. Sympathetic neuronal dysfunction in IOH is attended by a reduction in the clearance of NE. The very low plasma NE levels, in association with the striking reduction in NE clearance, suggest that in IOH there is a marked decrease in NE release. NE clearance and apparent NE secretion rate are normal in MSA, consistent with a central nervous system dysfunction in regulating the sympathetic nervous system. Neuronal uptake of NE in humans does not appear to be stereoselective.

Adult↗
PubMed1985

Methylphenidate and cognitive therapy: a comparison of treatment approaches with hyperactive boys.

This study of hyperactive boys evaluated the effects of three modes of treatment in relation to an untreated group. The treatments were administered over a 3-month period and included cognitive training, stimulant drug therapy (methylphenidate), and the two treatments combined. A follow-up assessment was conducted approximately 3 months after contact between the training staff and the child had ceased. Analyses of attentional deployment and cognitive style measures, tests of academic achievement, and behavioral ratings showed that only those children in the two medication treatment conditions demonstrated improvement in attentional deployment and behavioral ratings. In the cognitive therapy condition, there were changes only on measures of attentional deployment. The data did not provide evidence indicating that the combined medication and cognitive therapy condition was any more effective than that condition involving medication alone. Discussion provides future guidelines for evaluation of the relative effectiveness of stimulant drug therapy and other psychological treatment modalities.

Achievement↗