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Biomedical subjects

D Norman

Publications and source records attributed to D Norman.

At least 55 records · Page 3Linked to original sources
PubMed1998

Vascular deprivation-induced necrosis of the femoral head of the rat. An experimental model of avascular osteonecrosis in the skeletally immature individual or Legg-Perthes disease.

The blood supply of rats' femoral heads was severed by cutting the ligamentum teres and stripping the periostium. Histologically, necrosis of the marrow was apparent on the 2nd postoperative day, necrosis of the bone on the 5th postoperative day and fibrous ingrowth on the 7th postoperative day. During the following 5 weeks, progressive resorption of the intertrabecular necrotic debris and necrotic bony trabeculae and subchondral bone plate and, concurrently, appositional and intramembranous new bone formation resulted in remodeling of the femoral heads. In 2 of 7 femoral heads, replacement of the necrotic bone by viable bone was complete at the 42-day postoperative interval. Also, the articular cartilage of the deformed and flattened femoral heads was undergoing degenerative changes. Reduplicating the pathogenically inferred clinical settings of blood supply deprivation, it is proposed that this model, in a small laboratory animal, satisfies the requirements sought for preclinical studies of treatment modalities of avascular osteonecrosis in man.

Animals↗
PubMed1998

Alzheimer disease: quantitative H-1 MR spectroscopic imaging of frontoparietal brain.

PURPOSE: To replicate previous hydrogen-1 magnetic resonance (MR) spectroscopic imaging findings of metabolic abnormalities in patients with Alzheimer disease (AD), to verify that metabolic abnormalities are not an artifact of structural variations measured at MR imaging, to determine whether metabolic changes correlate with dementia severity, and to test whether MR imaging and MR spectroscopic imaging findings together improve ability to differentiate AD. MATERIALS AND METHODS: MR spectroscopic imaging and MR imaging were performed in 28 patients with AD and 22 healthy elderly subjects. Spectroscopic imaging data were coregistered with MR imaging segmentation data to obtain volume-corrected metabolite concentrations. RESULTS: Consistent with previous results, N-acetyl aspartate (NAA) levels were statistically significantly reduced in frontal and posterior mesial cortex of AD patients, presumably due to neuronal loss. NAA level reductions were independent of structural variations measured at MR imaging and, in parietal mesial cortex, were correlated mildly with dementia severity. Spectroscopic imaging findings of NAA level combined with MR imaging measures did not improve discrimination power for AD relative to that of MR imaging alone. CONCLUSION: Reduced NAA levels in frontoparietal brain are of limited use for diagnosis of AD. However, they are not an artifact of structural variations and thus may provide useful information for the understanding of the pathologic processes underlying AD.

Aged↗
PubMed1997

[Postoperative ulnar nerve palsy of the elbow].

Ulnar nerve neuropathy of the elbow is a recognized complication of surgery involving general anesthesia. In 13 patients, aged 21-76 years, ulnar nerve palsy developed at various times and of varying degrees of severity during the postoperative period. Diagnosis was based on clinical and electrophysiological findings. 3 patients had subclinical entrapment of the ulnar nerve. All were treated conservatively by rest, splinting and physical therapy: 10 improved slowly with time and 3 were operated on, but only 1 recovered fully. Preventive measures, such as proper positioning on the operative table, use of elbow pads, avoiding adduction of the arm, pronation of the forearm and prolonged elbow flexion, may reduce the incidence of ulnar nerve palsy. Unfortunately, treatment of established lesions has yielded mixed results.

Adult↗
PubMed1997

Ten-year results of the Oregon program with 295 consecutive heart transplants in the Pacific Northwest.

BACKGROUND: The Oregon Cardiac Transplant Program provides a regional service. Since December 4, 1985, 284 patients, including 14 children, from Oregon, Washington, Idaho, Alaska, and Hawaii, underwent 295 orthotopic heart transplantation procedures at the Oregon Health Sciences University. Eleven patients underwent transplantations twice. METHODS: Detailed, up-to-date follow-up data were available on all patients. All patients have been followed up prospectively for transplant-related complications. RESULTS: The most common recipient diagnoses were coronary artery disease (50%) or idiopathic cardiomyopathy (33%). The mean age of the recipients was 48 +/- 15 years (range, 3 months to 68 years). Donor hearts were retrieved from a procurement area of a 1,500-mile radius that involved Oregon, Washington, Idaho, Nevada, Utah, California, and Canada. The mean donor age was 28 +/- 11 years and the donor heart ischemia time was 180 +/- 56 minutes. The median recipient waiting time was 75 days. Operative mortality was 6%. One-year, 5-year, and 10-year actuarial patient survival rates are 86 +/- 2%, 74 +/- 3%, and 59 +/- 5%, respectively. The majority of survivors are in very good functional status. CONCLUSIONS: Now, more than 10 years into its existence, the Oregon Heart Transplant Program has fulfilled its goal of providing a most effective treatment option for patients with end-stage heart disease in the region.

Adolescent↗
PubMed1997

External fixation for severe open fractures of the humerus caused by missiles.

OBJECTIVE: To evaluate the use of external fixation of the humerus after missile injuries. DESIGN: Retrospective. SETTING: University medical center. PATIENTS: Twenty-six soldiers with twenty-six open Gustilo type III fractures. INTERVENTIONS: Immediate external fixation. MAIN OUTCOME MEASURES: Clinical, functional, social, and rehabilitation criteria were evaluated. RESULTS: Excellent in fourteen patients (61%), good in four (17%), fair in three (13%), and poor in two (9%). All fractures eventually healed. CONCLUSION: External fixation is the preferred initial treatment for stabilizing severe open missile fractures of the humerus. Its use, together with radical debridement of dead bone, has reduced the incidence of chronic infection and improved the prognosis of vascular repairs. As a result, the rate of morbidity and upper limb amputation has been reduced significantly, compared with our previous experience.

Adult↗
PubMed1997

1H MRSI of normal appearing white matter in multiple sclerosis.

The primary goal of this study was to determine if differences in proton magnetic resonance spectroscopy signals exist between normal appearing white matter (NAWM) of multiple sclerosis (MS) patients and white matter of control subjects. Water suppressed proton magnetic resonance spectroscopic imaging was used to determine the signal intensities of N-acetylated moieties (NA, predominantly N-acetylaspartate (NAA) the putative neuronal marker), creatine and phosphocreatine (Cr), and cholines (Ch) in 19 MS patients (15 relapsing-remitting and four secondary progressive) and 19 age matched control subjects. NA/Cr was significantly reduced (P < 0.001) in MS NAWM (1.8 +/- 0.2; x +/- s.d.) distant from MRI detected lesion areas compared to white matter of control subjects (2.1 +/- 0.2). This reduction was due to an increase in Cr from 0.39 +/- 0.04 (arbitrary units) in controls to 0.45 +/- 0.05 in MS patients. There was no significant change in NA or Ch in MS NAWM compared to controls. NA/Cr, distant from MRI lesion, was negatively correlated with total brain lesion volume as measured from T2-weighted MRI. We interpret the reduced NA/Cr in MS NAWM to indicate diffuse microscopic disease.

Adult↗
PubMed1997

Evidence for association of HLA-A2 allele with onset age of Alzheimer's disease.

Our earlier studies had suggested a possible association between the HLA-A2 allele and Alzheimer's disease (AD). In the present study we tested the hypothesis that A2 is associated with earlier AD onset. We performed two independent studies: a collaborative study with 111 patients and a confirmatory study with 96 patients. We found similar patterns of reduced age at onset as a function of A2 in both data sets. Overall, A2 was associated with a significant 3-year shift to earlier onset. The effects of A2 and epsilon 4 on age at onset appeared additive. Our results suggest A2, or a closely linked gene, modulates onset age of AD. Association with A2 would suggest an immune/inflammatory response mechanism for AD.

Age of Onset↗
PubMed1997

Changes of hippocampal N-acetyl aspartate and volume in Alzheimer's disease. A proton MR spectroscopic imaging and MRI study.

Hippocampal atrophy detected by MRI is a prominent feature of early Alzheimer's disease (AD), but it is likely that MRI underestimates the degree of hippocampal neuron loss, because reactive gliosis attenuates atrophy. We tested the hypothesis that hippocampal N-acetyl aspartate (NAA: a neuronal marker) and volume used together provide greater discrimination between AD and normal elderly than does either measure alone. We used proton MR spectroscopic imaging (1H MRSI) and tissue segmented and volumetric MR images to measure atrophy-corrected hippocampal NAA and volumes in 12 AD patients (mild to moderate severity) and 17 control subjects of comparable age. In AD, atrophy-corrected NAA from the hippocampal region was reduced by 15.5% on the right and 16.2% on the left (both p < 0.003), and hippocampal volumes were smaller by 20.1% (p < 0.003) on the right and 21.8% (p < 0.001) on the left when compared with control subjects. The NAA reductions and volume losses made independent contributions to the discrimination of AD patients from control subjects. When used separately, neither hippocampal NAA nor volume achieved to classify correctly AD patients better than 80%. When used together, however, the two measures correctly classified 90% of AD patients and 94% of control subjects. In conclusion, hippocampal NAA measured by 1H MRSI combined with quantitative measurements of hippocampal atrophy by MRI may improve diagnosis of AD.

Aged↗
PubMed1997

Cognitive test performance and background music.

This study examined the effects of background music on test performance. In a repeated-measures design 30 undergraduates completed two cognitive tests, one in silence and the other with background music. Analysis suggested that music facilitated cognitive performance compared with the control condition of no music: more questions were completed and more answers were correct. There was no difference in heart rate under the two conditions. The improved performance under the music condition might be directly related to the type of music used.

Acoustic Stimulation↗
PubMed1997

Tissue segmentation of the brain in Alzheimer disease.

PURPOSE: To compare brain tissue in patients with Alzheimer disease with that in elderly control subjects by using high-resolution MR imaging and quantitative tissue-segmentation techniques. METHODS: MR imaging of the brain was performed in 21 patients with Alzheimer disease and 17 control subjects. A computerized segmentation program was used to quantify volumes of ventricular and sulcal cerebrospinal fluid (CSF), white matter, cortical gray matter, and white matter signal hyperintensity. Statistical analysis was performed using analysis of variance. RESULTS: We found a significant decrease in total brain tissue and cortical gray matter and an increase in the ventricular and sulcal CSF in Alzheimer patients compared with control subjects. There was no difference in the volume of white matter. More white matter signal hyperintensities were found in Alzheimer patients, and a significant interaction between age and group was noted. Neuropsychological test scores correlated significantly with sulcal CSF in patients with Alzheimer disease. CONCLUSION: Semiautomated segmentation of MR images of the brains of patients with Alzheimer disease reveals significant brain atrophy attributable to loss of cortical gray matter, which is compatible with the pathologic features of Alzheimer disease. There is also a significant increase in white matter signal hyperintensities. Tissue segmentation may increase our understanding of dementia but, as yet, when used alone, it does not play a role in the premorbid diagnosis of Alzheimer disease.

Aged↗
PubMed1997

Brain atrophy in HIV infection is more strongly associated with CDC clinical stage than with cognitive impairment.

HIV infection often results in MRI-detectable brain atrophy and white matter signal hyperintensities (WMSHs). Magnetic resonance images were obtained from 31 HIV+ male patients and 10 high-risk controls. Variation within the HIV+ group on neuropsychological (NP) impairment and stage of systemic disease were relatively independent, allowing examination of the relative association of MRI measures with NP impairment versus with systemic stage of disease. HIV+ patients compared to high-risk controls evidenced global atrophy, reduced caudate nuclei volume, and a trend to gray matter volume loss but no difference in white matter volume or in WMSHs. These effects were progressive with CDC clinical stage such that patients at CDC stage A had values very close to those of controls, while patients at CDC stage C had the most abnormal values. In contrast, the relationship between these MRI variables and severity of NP impairment was much less dramatic, with the mildly to moderately impaired HIV+ subjects showing MRI volume effects greater than or equal to those of the severely impaired HIV+ subjects. These results suggest that MRI-detectable brain atrophy secondary to HIV infection is not the primary substrate underlying the progressive NP impairment in HIV disease.

AIDS Dementia Complex↗
PubMed1996

[External humeral fixation in war injuries].

Type III open fractures of the humerus caused by high energy missiles or shrapnel in 26 male soldiers were treated by external fixation. 12 suffered from associated injuries involving the head and chest, 12 had 14 nerve injuries, and 4 required simultaneous repair of the brachial artery. Results in 19 examined after an average of 6.5 years were excellent in 22%, good in 52%, fair in 16%, and poor in 10%. The aim of external fixation is functional limb salvage. We think high-energy gunshot fractures should be classified as III-d because of the severe damage to the soft tissue, which differs from that of low-velocity, gunshot fractures or farm injuries. We conclude that external fixation is the preferred form of primary stabilization of severe open fractures of the humerus. It has reduced the incidence of chronic infection and has improved the prognosis of vascular repairs. The treatment of the soft tissues, skin coverage, and ultimately reconstructive surgery are facilitated. Early limb function allows for a better final result. For delayed union and pin-tract infection a different definitive method, such as internal fixation or a plaster case, is required.

External Fixators↗
PubMed1996

Regional gray and white matter metabolite differences in subjects with AD, with subcortical ischemic vascular dementia, and elderly controls with 1H magnetic resonance spectroscopic imaging.

OBJECTIVE: To use 1H magnetic resonance spectroscopic imaging to study differences in neuron density (N-acetylaspartate [NAA]), membrane phospholipid metabolites (choline [Cho]), and creatine-containing metabolites (creatine plus phosphocreatine [Cr]) in subjects with Alzheimer's disease (AD), with subcortical ischemic vascular dementia (SIVD), and elderly controls. DESIGN: Cross-sectional, between groups. SETTING: A Veterans Affairs medical center and university memory clinic. PARTICIPANTS: Forty elderly subjects with AD (n = 14), with SIVD (n = 8), and elderly controls (n = 18). MAIN OUTCOME MEASURES: We used 1H magnetic resonance spectroscopic imaging to acquire spectra from a 80 x 100 x 17-mm volume superior to the lateral ventricles. Spectra were analyzed from voxels in anterior, medial, and posterior gray and white matter using nuclear magnetic resonance-1 and the results were compared between groups using repeated measures analysis of variance (ANOVA), Tukey's test, and individual Student's t tests. RESULTS: Using ANOVA, significantly lower levels of NAA/Cho and NAA/Cr and significantly higher levels of Cho/Cr were observed across both gray and white matter voxels in subjects with AD. Using individual Student's t tests, a significantly lower level of NAA/Cho and a higher level of Cho/Cr were observed in the posterior gray matter in subjects with AD. Using ANOVA in subjects with SIVD, significantly lower gray and white matter NAA/Cr levels were observed. Using Tukey's test, the NAA/Cr level was significantly lower in frontal white matter voxels in subjects with SIVD compared with controls. CONCLUSIONS: Our findings in subjects with AD suggest neuron loss in gray matter, axon loss in white matter, and altered Cho metabolism in posterior brain regions. Our findings in subjects with SIVD are consistent with higher levels of creatine-containing metabolites and/or lower levels of NAA in frontal white matter.

Aged↗
PubMed1996

A prospective 4-year follow-up study of attention-deficit hyperactivity and related disorders.

BACKGROUND: Previous cross-sectional data showed that children and adolescents with attention-deficit hyperactivity disorder (ADHD) are at increased risk of comorbid conduct, mood, and anxiety disorders as well as impairments in cognitive, social, family, and school functioning. However, longitudinal data were needed to confirm these initial impressions. METHODS: Using DSM-III-R structured diagnostic interviews and raters blinded as to diagnosis, we reexamined psychiatric diagnoses at 1- and 4-year follow-ups in children with ADHD and controls. In addition, subjects were evaluated for cognitive, achievement, social, school and family functioning. RESULTS: Analyses of follow-up findings revealed significant differences between children with ADHD and controls in rates of behavioral, mood, and anxiety disorders, with these disorders increasing markedly from baseline to follow-up assessments. In addition, children with ADHD had significantly more impaired cognitive, family, school, and psychosocial functioning than did controls. Baseline diagnosis of conduct disorder predicted major depression and bipolar disorder at follow-up, and anxiety disorders at baseline predicted anxiety disorders at follow-up. CONCLUSION: These results confirm and extend previous retrospective results indicating that children with ADHD are at high risk of developing a wide range of impairments affecting multiple domains of psychopathology such as cognition, interpersonal, school, and family functioning. These findings provide further support for the value of considering psychiatric comorbidity in both clinical assessment and research protocols involving children with ADHD.

Achievement↗
PubMed1996

Vascular complications in lumbar disk surgery: report of four cases.

Vascular injuries in lumbar disk surgery, although rare, are serious complications which may be overlooked due to a broad range of clinical manifestations. It is important that surgeons and radiologists be aware of these potentially fatal complications and develop an appropriate symptom-based diagnostic paradigm. We reviewed 8099 consecutive cases of lumbar disk surgery, performed over a 14-year period at a single institution, for postoperative vascular complications. We identified four patients (0.05%) with lumbar disk surgery-related vascular complications: intraoperative lacerations of the abdominal aorta and median sacral artery, an arteriovenous fistula between the left common iliac artery and vein detected 19 days postdiskectomy, and a partially thrombosed aortic aneurysm with an arteriovenous fistula between the aneurysm and the inferior vena cava, diagnosed 11 months after surgery. The majority of cases in the literature of vascular injury in lumbar disk surgery were reported prior to 1965. Diagnostic approaches described in that period do not reflect the great range of diagnostic techniques available today. Angiography remains the gold standard for diagnosis and guidance as to surgical repair. However, a high index of suspicion based on clinical signs and/or the use of sonography or CT is important in the detection of these complications.

Aged↗
PubMed1996

Postprandial insulin profiles with implantable pump therapy may explain decreased frequency of severe hypoglycemia, compared with intensive subcutaneous regimens, in insulin-dependent diabetes mellitus patients.

PURPOSE: To examine the mechanism of the decreased frequency of severe hypoglycemia with implantable pump therapy compared with subcutaneous intensive therapy. PATIENTS AND METHODS: Eight subjects with insulin-dependent diabetes mellitus (IDDM), enrolled in an implantable insulin pump study, were admitted to the General Clinical Research Center and on 2 separate days were given either a dose of preprandial insulin chosen to maintain normoglycemia for a standard (450 kcal, 50% carbohydrate) breakfast or 1.75 times the dose. The two doses were administered subcutaneously (by syringe or with an external pump) during one inpatient admission and by implantable pump (intraperitoneally, n=6; or intravenously, n=2) during a separate admission. Blood glucose, plasma-free insulin, and neurocognitive function were measured for 4 hours after the meal. RESULTS: Subcutaneous administration resulted in 7 episodes of hypoglycemia (2 with the usual dose and 5 with the 1.75-fold dose), defined as blood glucose less than 50 mg/dL; implantable pump treatment resulted in only 2 episodes, both with the 1.75-fold dose (P <0.05, Fisher's two-tailed test for implantable versus subcutaneous). Compared with subcutaneous delivery, implantable pump therapy provided significantly lower insulin levels during the final 2 hours after administration of the usual dose and the 1.75-fold dose (P <0.005). In addition to the decreased frequency of hypoglycemia, implantable pump therapy resulted in significantly lower area under the glycemia curve during the first 120 minutes with the 1.75-fold dose compared with subcutaneous administration. CONCLUSIONS: The lower frequency of severe hypoglycemia with intensive therapy administered by implantable pump therapy is explained by the more rapid clearance of insulin delivered intraperitoneally or intravenously compared with intensive subcutaneous injection regimens. The lower frequency of severe hypoglycemia with implantable pump therapy compared with subcutaneous therapy demonstrated in clinical trials is confirmed by this study, in which we attempted to induce hypoglycemia.

Adult↗