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Biomedical subjects

E J Russell

Publications and source records attributed to E J Russell.

At least 19 recordsLinked to original sources
PubMed2000

The properties of retention intervals and their affect on retaining prospective memories.

Five experiments were conducted to explore how the character of the retention interval affected event-based prospective memory. According to the canons of retrospective memory, prospective performance should have been worse with increasing delays between intention formation and the time it was appropriate to complete an action. That result did not occur. Rather, prospective memory was better with increasing retention intervals in Experiments 1A, 1B, and 3. In manipulating the nature of the retention interval, the authors found that there were independent contributions of retention interval length and the number of intervening activities, with more activities leading to better prospective memory (Experiments 2 and 3). The identical retention intervals did not improve retrospective memory in Experiment 4. Theoretical explanations for these dissociations between prospective and retrospective memory are considered.

Adult↗
PubMed2000

Pituitary hypoplasia in patients with a mutation in the growth hormone-releasing hormone receptor gene.

BACKGROUND AND PURPOSE: Several anatomic abnormalities of the pituitary gland have been described as occurring in association with congenital growth hormone deficiency, including hypoplasia of the adenohypophysis, truncation of the pituitary stalk, and ectopia of the neurohypophysis. Their pathogenesis, however, is obscure. Normal pituitary development is dependent on the sequential expression of a series of ontogenetic factors. Growth hormone-releasing hormone (GHRH) is known to stimulate somatotroph proliferation, and a dwarf mouse model with a mutant GHRH receptor, the "little mouse," has a small anterior pituitary due to hypoplasia of the somatotrophs. We recently described the human homolog of the little mouse (dwarfism of Sindh), caused by a homozygous nonsense mutation in the GHRH receptor gene in a Pakistani kindred. We investigated MR imaging characteristics to gain information regarding the potential role of GHRH in human pituitary organogenesis. METHODS: MR images of the head were obtained of four affected male patients (age range, 22-29 years). Maximal anterior pituitary dimensions were determined from sagittal and coronal images, and pituitary volumes were estimated from cubic and ellipsoid formulae. The measurements were compared with normative values matched for age and sex. RESULTS: The adenohypophysis was small in each of the four patients. The maximal height for the anterior pituitary was 3 mm in three patients and 2 mm in one (mean +/- SD, 2.75 +/- 0.5 mm), which is significantly (P < .001) less than the expected height of 5.6 +/- 1.0 mm for men in this age group. Estimates of anterior pituitary volume in the patients ranged from 75 to 124 mm3 (104 +/- 21 mm3), which corresponds to 35% to 52% of the normal mean volume corrected for small head size (P < .005). No other cranial abnormalities were identified. CONCLUSION: We describe significant hypoplasia of the adenohypophysis occurring in four dwarfs with a nonsense mutation in the GHRH receptor. In addition to isolated growth hormone deficiency and severe dwarfism, affected patients have anterior pituitary hypoplasia, presumably due to somatotroph maldevelopment. Resistance to GHRH explains the hypoplasia of the adenohypophysis--a feature that contributes to growth hormone deficiency in this syndrome. This is one of the few instances in which the molecular basis of pituitary dysmorphogenesis has been identified.

Adult↗
PubMed1999

Current approaches to imaging of the sellar region and pituitary.

Recent advances in MR imaging have enabled the radiologist to view the pituitary gland in its normal and diseased states to a greater extent than ever before. The techniques for obtaining quality images of the sellar region and the normal appearance of the pituitary gland are discussed. This article also discusses the imaging of several pituitary disease processes, with emphasis on pitutiary adenomas and recent advances in diagnosis and follow-up. Current controversies also are addressed.

Adenoma↗
PubMed1999

Persistence of the notochordal canal: MR and plain film appearance.

We report a case of an unusually prominent persistent notochordal canal involving the T12-L5 vertebrae. This rare anatomic variation was discovered as an incidental finding in a patient with lymphoma undergoing MR imaging for evaluation of back pain. MR images showed a vertically oriented canal contiguous with the intervertebral disks traversing the anterior aspect of each affected vertebral body. Plain films showed a sclerotic rimmed central channel that flared at each vertebral endplate to merge with the disk spaces.

Adult↗
PubMed1998

T cell-depleted autologous hematopoietic stem cell transplantation for multiple sclerosis: report on the first three patients.

Multiple sclerosis (MS) is a disease of the central nervous system characterized by immune-mediated destruction of myelin. In patients with progressive deterioration, we have intensified immunosuppression to the point of myeloablation. Subsequently, a new hematopoietic and immune system is generated by infusion of CD34-positive hematopoietic stem cells (HSC). Three patients with clinical MS and a decline of their Kurtzke extended disability status scale (EDSS) by 1.5 points over the 12 months preceding enrollment and a Kurtzke EDSS of 8.0 at the time of enrollment were treated with hematopoietic stem cell (HSC) transplantation using a myeloablative conditioning regimen of cyclophosphamide (120 mg/kg), methylprednisolone (4 g) and total body irradiation (1200 cGy). Reconstitution of hematopoiesis was achieved with CD34-enriched stem cells. The average time of follow-up is 8 months (range 6-10 months). Despite withdrawal of all immunosuppressive medications, functional improvements have occurred in all three patients. We conclude that T cell-depleted hematopoietic stem cell transplantation can be performed safely in patients with severe and debilitating multiple sclerosis. Stem cell transplantation has resulted in modest neurologic improvements for the first time since onset of progressive disease although no significant changes in EDSS or NRS scales are evident at this time.

Adult↗
PubMed1998

Imaging of angiographically occult cerebral vascular malformations.

The angiographically occult vascular malformations represent an important cause of cerebral pathology. The propensity for significant yet often limited symptomatology provides for frequent challenge in clinical management. Understanding in diagnostic evaluation of occult vascular lesions is often limited by varying application of pathologic diagnosis and classification. This article attempts to clarify issues of classification while also discussing imaging evaluation and its role in clinical management.

Brain Neoplasms↗
PubMed1997

Contrast-enhanced magnetization transfer MR of the brain: importance of precontrast images.

PURPOSE: To determine the importance of obtaining precontrast T1-weighted magnetization transfer (MT) MR images for better interpretation contrast-enhanced T1-weighted MT images. METHODS: One hundred fifty-five patients referred for MR imaging of the brain were examined prospectively with noncontrast T1-weighted imaging, noncontrast T1-weighted imaging with MT, contrast-enhanced T1-weighted imaging, and contrast-enhanced T1-weighted imaging with MT. In the patients who had abnormally increased signal intensity on postcontrast images (with or without MT), the four imaging sequences were evaluated with regard to number of lesions and lesional signal intensity. For each of the sequences, two experienced neuroradiologists subjectively graded the lesions on a scale of 1 to 4 (4 being the most conspicuous) with regard to abnormally increased signal intensity. RESULTS: Twenty-two of the 155 patients had increased signal intensity on one or more of the postcontrast sequences. Eight of these 22 patients had increased signal intensity of one or more lesions on images without MT. All these lesions were seen better on images obtained with MT. An additional six of the 22 patients had increased signal intensity of one or more lesions on images obtained with MT that was not detected on images obtained without MT. Eight of the 22 patients had no high signal intensity on noncontrast images with or without MT. One of the eight had increased number and conspicuity of lesions on postcontrast MT images. CONCLUSIONS: A significant number of patients had increased signal intensity on noncontrast T1-weighted images with MT that was not seen on noncontrast T1-weighted images without MT. This high signal intensity was also visible on postcontrast MT images, and would have been mistaken for pathologic enhancement if noncontrast MT images had not been available for comparison.

Adult↗
PubMed1996

Radiation-induced changes in the central nervous system and head and neck.

Radiation therapy of the brain, neck, and spine can be associated with radiation-induced changes that are increasingly evident radiologically. These changes affect the central nervous system (focal necrosis, diffuse white matter injury, atrophy, mineralizing microangiopathy, telangiectasia, optic neuropathy, large vessel vasculopathy), bone (fatty replacement of marrow, osteoradionecrosis, sinus inflammation), and superficial and deep soft tissues and include neoplasia. Focal necrosis, which most commonly occurs at the treatment site, is seen at computed tomography (CT) and magnetic resonance (MR) imaging as a ring-enhancing mass with edema and mass effect, findings similar to those of tumor recurrence. Diffuse white matter injury appears as hypoattenuating (at CT) or hyperintense (at MR imaging) small foci near the frontal or occipital horns or as a confluent band extending from the ventricles to the corticomedullary junction. Fatty replacement of marrow is the most common osseous complication seen on MR images. Osteoradionecrosis, which occurs most often in the mandible, appears as a focal lytic area at CT and with abnormal marrow signal and cortical destruction at MR imaging. The most common changes in the superficial soft tissues of the head and neck, edema and fibrosis, are seen radiologically as skin thickening and increased soft-tissue attenuation with stranding of subcutaneous fat. Meningioma, the most common radiation-induced CNS tumor, can be distinguished from spontaneous meningiomas on the basis of clinical characteristics (eg, presence of focal alopecia and scalp atrophy).

Adolescent↗
PubMed1996

Spinal cord venous infarction following endoscopic sclerotherapy for esophageal varices.

The authors report an unusual case of venous infarction of the spinal cord associated with endoscopic sclerotherapy for esophageal varices. MR imaging findings included signal abnormalities and abnormal enhancement of the affected spinal cord and T-8 vertebral body. A review of the hemodynamic changes associated with portal hypertension and the normal venous drainage of the spinal cord is presented.

Esophageal and Gastric Varices↗
PubMed1996

Osteochondroma of the thoracic spine: an unusual cause of spinal cord compression.

A 24-year-old man with hereditary multiple exostoses had numbness of the lower extremities and difficulty walking. CT displayed a calcified extradural mass lesion within the spinal canal at T-8 causing cord compression. MR imaging showed it to be contiguous with the upper endplate of T-8, suggesting the diagnosis of osteochondroma, a rare cause of cord compression, and distinguishing the lesion from a calcified disk fragment.

Adult↗
PubMed1996

Location of the central sulcus via cortical thickness of the precentral and postcentral gyri on MR.

PURPOSE: To determine whether relative cortical thickness measurements of the precentral and postcentral gyri can be used to differentiate the central sulcus from adjacent cortical sulci. METHODS: Turbo inversion-recovery MR imaging of the entire brain was done with scans parallel to the anterior commissure-posterior commissure line. Cortical thickness was measured in each hemisphere with a jeweler's eyepiece with 0.1-mm gradations. Three measurements were obtained perpendicular to the central, precentral, and superior frontal sulci, as determined by means of established anatomic methods. The ratios of cortical thickness on both sides of the central, precentral, and superior frontal sulci were calculated and compared. RESULTS: The mean ratio of precentral/postcentral gyri was 1.64 for the right hemisphere and 1.53 for the left hemisphere. The mean cortical thickness ratios were as follows: 1.01 for the right hemisphere and 3.01 for the left hemisphere across the precentral sulcus, and 1.03 for the right hemisphere and 0.99 for the left hemisphere across the superior frontal sulcus. CONCLUSION: Cortical thickness measurements across the central sulcus provide a method for locating the primary motor (precentral gyri) and primary somatosensory (postcentral gyri) cortices. The higher mean cortical thickness ratio across the central sulcus corresponds with known cytoarchitectonic relationships.

Adult↗
PubMed1995

High-resolution CT of mastoid sinus pneumocele with external auditory canal stenosis.

A 34-year-old man presented with tinnitus and conductive hearing loss. CT demonstrated an expansile, air-containing cavity contiguous with mastoid air cells, narrowing the external auditory canal. This is a case of symptomatic pneumocele resulting in an air collection beneath external canal lining, possibly related to an abnormality in mastoid fusion.

Adult↗