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Biomedical subjects

D Norman

Publications and source records attributed to D Norman.

At least 91 records · Page 5Linked to original sources
PubMed1993

Patterns of psychiatric comorbidity, cognition, and psychosocial functioning in adults with attention deficit hyperactivity disorder.

OBJECTIVE: Although attention deficit hyperactivity disorder is a common disorder of childhood, its status as a disorder in adults is not clear. The authors reasoned that if the adult diagnosis of the disorder is a valid clinical entity, it should be similar to the childhood disorder with regard to patterns of psychiatric and cognitive findings. METHODS: Eighty-four adults with a clinical diagnosis of childhood-onset attention deficit hyperactivity disorder confirmed by structured interview who were referred for treatment were studied. Findings were compared with those from a preexisting study group of referred children with attention deficit hyperactivity disorder, nonreferred adult relatives of those children who also had attention deficit hyperactivity disorder, and adults without the disorder who were relatives of normal children. Subjects were evaluated with a comprehensive battery of psychiatric, cognitive, and psychosocial assessments. RESULTS: The referred and nonreferred adults with attention deficit hyperactivity disorder were similar to one another but more disturbed and impaired than the comparison subjects without the disorder. The pattern of psychopathology, cognition, and functioning among the adults with attention deficit hyperactivity disorder approximated the findings for children with the disorder. CONCLUSIONS: These results show that referred and nonreferred adults with attention deficit hyperactivity disorder have a pattern of demographic, psychosocial, psychiatric, and cognitive features that mirrors well-documented findings among children with the disorder. These findings further support the validity of the diagnosis for adults.

Adult↗
PubMed1993

Evidence for the independent familial transmission of attention deficit hyperactivity disorder and learning disabilities: results from a family genetic study.

OBJECTIVE: The purpose of the study was to clarify the relationship between attention deficit hyperactivity disorder and learning disabilities. METHOD: The authors assessed learning disabilities in a sample of 140 children with attention deficit hyperactivity disorder and in 120 normal comparison children. They also assessed a sample of the probands' 822 first-degree relatives. RESULTS: The risk for learning disabilities was highest among relatives of probands with both attention deficit hyperactivity disorder and learning disabilities. The two disorders did not cosegregate in families. There was nonrandom mating between spouses with attention deficit hyperactivity disorder and learning disabilities. CONCLUSIONS: The two disorders are transmitted independently in families, and their co-occurrence may be due to nonrandom mating. Attention deficit hyperactivity disorder is likely to be etiologically independent from learning disabilities.

Adult↗
PubMed1992

Hypercarbia-induced changes in cerebral blood volume in the cat: a 1H MRI and intravascular contrast agent study.

Cerebral blood volume changes with arterial carbon dioxide were monitored by proton T1-weighted MR images following administration of the intravascular contrast agent Gd-DTPA labeled with human serum albumin. Without MR contrast, no significant image intensity changes were observed with PaCO2. Following contrast, regional brain image intensities increased significantly over control (0% inspired CO2) in cortical gray, white, and basal ganglia regions with increasing PaCO2 and returned to control intensities upon return to 0% inspired CO2. Imaging of through-plane and in-plane phantoms was performed to assess flow effects. Signal losses of 2 and 6% (relative to no flow) were observed for bulk velocities of 5 mm/s at TE values of 15 ms. An intravascular contrast agent may be useful for MRI monitoring of local cerebral blood volume changes during cerebral perturbations.

Adipose Tissue↗
PubMed1992

Comorbidity between ADDH and learning disability: a review and report in a clinically referred sample.

A widely variable overlap ranging from 10 to 92% has been reported in the literature between attention deficit disorder with hyperactivity (ADDH) and learning disability (LD), most likely a result of inconsistencies in the criteria used to define LD in different studies. The following study seeks to more accurately determine rates of LD in clinically referred children. Using a psychometrically reliable methodological approach, it was expected that the rate of LD in ADDH children would be far more modest than previously reported. Subjects were referred children with ADDH (N = 60), children with academic problems (N = 30), and normal controls (N = 36) of both sexes with available psychological and achievement testing. Using a liberal definition of LD, significant differences were found between the groups (ADDH = 38% versus academic problems = 43% versus normals = 8%; p = 0.002). In contrast, more modest rates were found using two more stringent methods of assessment (23 and 17%; 10 and 3%; 2 and 0%, respectively; p = 0.02). Arithmetic-based LD appears to be equally identified by both stringent methods, whereas the liberal definition overidentified children in all three groups. These findings show that a liberal definition of LD overidentifies LD not only in ADDH children but also in normal children.

Achievement↗
PubMed1992

Cytotoxic brain edema: assessment with diffusion-weighted MR imaging.

To determine whether cytotoxic brain edema is associated with a decrease in diffusion, it was induced in rats, in the absence of ischemia, with an established model of acute hyponatremic encephalopathy. Cytotoxic brain edema secondary to acute hyponatremia was induced with intraperitoneal injections of 2.5% dextrose in water and subcutaneous injection of arginine-vasopressin. Coronal spin-echo magnetic resonance (MR) images were obtained with and without strong diffusion-sensitizing gradients before and after induction of acute hyponatremia. The apparent diffusion coefficient (ADC) was measured at two coronal section locations. In hyponatremic rats, the brain ADC was significantly reduced (P = .0153 and .0001) and was positively correlated with increased total brain water content (P = .0011). Plots of ADC versus total brain water showed a statistically significant inverse linear relationship between ADC and increasing brain water at the anterior coronal section location. The results indicate that the ADC may be a sensitive indicator of cytotoxic brain edema and thus may enable quantitative evaluation of such edema with diffusion-weighted MR imaging.

Animals↗
PubMed1992

In vitro tumor necrosis factor-alpha secretion by monocytes from patients with cystic fibrosis.

Immunoreactive tumor necrosis factor-alpha (TNF-alpha) concentration is increased in plasma from patients with cystic fibrosis and chronic Pseudomonas aeruginosa pulmonary infection. To determine if circulating monocytes could be the source of plasma TNF-alpha, we determined in vitro basal and endotoxin-stimulated TNF-alpha secretion by monocytes. In 10 adult patients studied at the time of a symptomatic respiratory exacerbation, basal secretion of TNF-alpha was significantly less than that for 10 matched healthy controls (median 265 pg/micrograms DNA, nonparametric 95% confidence interval 193 to 463 pg/micrograms DNA versus 575, 298 to 923 pg/micrograms DNA; P less than 0.006), although both groups responded equally effectively to added Escherichia coli endotoxin at greater than or equal to 25 ng/ml. In six patients and six matched controls, monocyte culture was repeated after completion of 2 wk anti-pseudomonal antibiotic treatment in the patients. The reduced basal TNF-alpha secretion in the patients had reversed and was not significantly different to that of controls. This effect mirrored a significant reduction in plasma immunoreactive TNF-alpha in these patients (mean +/- SD, 258 +/- 59.3 pg/ml pretreatment versus 133 +/- 47.8 pg/ml post-treatment; P less than 0.05). These findings suggest that a reversible downregulation of TNF-alpha secretion occurred at the time of a symptomatic respiratory deterioration in the presence of chronic P. aeruginosa infection. This may represent a physiologic regulatory mechanism to maintain a local inflammatory response to chronic pulmonary infection in cystic fibrosis.

Adolescent↗
PubMed1992

Radiologic characteristics and results of surgical management of Rathke's cysts in 43 patients.

Although Rathke's cysts are a relatively common autopsy finding, rarely have they been reported as a clinical entity. Because of recent improvements in neuroradiological imaging, cystic intrasellar and suprasellar lesions are discovered often, leading to questions about proper management. Against this background, we reviewed the data from 43 patients with Rathke's cysts treated by one neurosurgeon over a 13-year period, and present the results here. The 43 patients had a mean age of 34 years, and 77% were female. Headache was the most common symptom, followed by galactorrhea, visual field loss, and hypopituitarism. Computed tomographic (CT) scans were reviewed in 20 cases, magnetic resonance (MR) images were reviewed in 15, and both CT and MR studies were reviewed in 5 cases. Although all Rathke's cysts were discrete and well-defined by both CT and MR imaging, the diversity of locations, CT attenuations, and MR signal intensity make it difficult to establish the diagnosis by radiological criteria. Forty patients underwent transsphenoidal surgery and three underwent craniotomy. There was one recurrence at 25 months requiring a second operation, and the mean follow-up period was 62 months. Seven patients had persistent headaches. For symptomatic lesions suspected to be Rathke's cysts, the recommended treatment is simple drainage of the cyst with biopsy of the wall, when this can be done safely. Follow-up imaging should be minimal for asymptomatic patients, and radiation therapy is not indicated.

Adolescent↗
PubMed1991

Magnetic resonance imaging evaluation of uveal tumors.

We detected seven tumors with magnetic resonance imaging, which demonstrate some of the uses and limitations of this diagnostic technique. In one patient, the correct diagnosis of extraocular extension was demonstrated with magnetic resonance imaging when both clinical and ultrasonographic data were not diagnostic. In another case, an extremely small area of extraocular extension was detected with ultrasound evaluation but was not noted on magnetic resonance imaging. Magnetic resonance imaging is highly reliable in the detection of intraocular tumors. In pigmented uveal melanomas it is both sensitive and highly specific. In amelanotic processes magnetic resonance imaging can identify a mass but cannot always adequately characterize it. Further experience will be necessary to determine the proper role of magnetic resonance imaging in the evaluation of uveal tumors.

Adult↗
PubMed1991

Diffusion-weighted MR imaging of extraaxial tumors.

The clinical usefulness of the application of spin-echo diffusion-weighted imaging in the evaluation of extraaxial cysts and epidermoid tumors is demonstrated in a series of 15 patients. Apparent diffusion coefficient (ADC) images based on intravoxel incoherent motion (IVIM) were obtained with a maximum gradient b value = 100 s/mm2. Lesion ADC was qualitatively compared to external phantoms. In all cases, epidermoid tumors revealed reduced ADC values similar to that of normal brain tissue. On the other hand, all cysts had ADC similar to the stationary water phantom. Lesion delineation was improved due to the replacement of normal pulsatile (very high ADC) cisternal CSF. Direct quantitative measurements of ADC using this technique may not be possible due to unavoidable motion artifact.

Brain↗
PubMed1991

Anisotropy in diffusion-weighted MRI.

Diffusional anisotropy of water protons, induced by nonrandom, directional barriers which hinder or retard water motion, is measurable by MRI. Faster water diffusion was observed when the diffusion-sensitizing gradient direction paralleled the long axes of white matter tracts, indicative of fewer barriers to water motion. Diffusion perpendicular to this axis was as much as four times slower. Anisotropy was seen pre- and postmortem in all axial, sagittal, and coronal planes, with and without cardiac gating. Ordering has also been observed in feline optic nerve and in human peripheral nerves. Utilization of this technique can greatly improve understanding and assessment of demyelinating disorders, of white matter infarcts and neoplasms, and of neonatal brain and spinal cord development.

Animals↗
PubMed1991

Inflammatory markers in cystic fibrosis.

Plasma neutrophil elastase-alpha 1 antiproteinase complex, lactoferrin and C-reactive protein (CRP) were determined over a 15-month period in 26 patients with cystic fibrosis, of whom 21 were chronically infected with Pseudomonas aeruginosa. Median concentrations of both neutrophil products and CRP were greater in patients who were clinically stable than in healthy subjects without cystic fibrosis. CRP concentrations increased further at the onset of symptomatic exacerbations. Thirty-five courses of intravenous antibiotics and 22 courses of oral ciprofloxacin were reviewed and revealed similar improvements in clinical scores and lung function tests for both forms of treatment. Intravenous antibiotics reduced the plasma concentrations of both neutrophil products and CRP, while oral ciprofloxacin only significantly reduced the concentration of neutrophil elastase-alpha 1 antiproteinase complex. Plasma concentrations of inflammatory markers were significantly greater in exacerbations associated with fever and leukocytosis. Statistical modelling demonstrated negative within-patient relationships between lung function and both CRP and lactoferrin, and positive relationships between the three inflammatory markers. Neutrophil granule products and CRP reflect the pulmonary inflammatory state in cystic fibrosis and may be of value in monitoring treatment.

Adolescent↗
PubMed1991

Effect of age on fever response to recombinant tumor necrosis factor alpha in a murine model.

Certain elderly humans show a blunted fever response to infection. A study was designed using a murine model to assess the influence of age on the febrile response to the endogenous pyrogen, tumor necrosis factor alpha (TNF alpha). Twenty (10 young: 4-6 months; 10 old: 24-28 months) BALB/c mice were injected with 50 ng of TNF alpha into the intraperitoneal space; the experiments were repeated one week later with 100 ng TNF alpha. Control animals received intraperitoneal injections of pyrogen-free phosphate buffered saline. Temperatures were measured rectally at baseline and at 10-minute intervals for 90 minutes post-injection using a thermistor probe and temperature gauge. In the majority of the time intervals following injection, the mean temperature changes of young mice were significantly higher than old mice for both 50 ng and 100 ng doses of TNF alpha. Similarly, peak temperature changes from baseline were consistently higher in young animals following injection of TNF alpha. Moreover, the peak temperature changes in young mice after 50 ng TNF alpha injection were significantly higher than those in old mice following a 100 ng injection of TNF alpha. These findings confirm that (a) TNF alpha has a role in the pathogenesis of fever; (b) aging alters significantly the febrile response; and (c) a mechanism of this age-related blunted febrile response may involve TNF alpha.

Aging↗