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Biomedical subjects

J H Allen

Publications and source records attributed to J H Allen.

49 records · Page 3Linked to original sources
PubMedDate not supplied

Diagnosis of spinal arteriovenous malformation in a pregnant patient by MR imaging.

An intraspinal arteriovenous malformation (AVM) was diagnosed by magnetic resonance imaging in a pregnant patient. Serpentine areas of low signal intensity surrounded by cerebrospinal fluid were considered diagnostic of this surgically verified abnormality. In addition, T2 weighted images helped to determine the extent of the spinal canal occupied by the AVM.

Adult↗
PubMedDate not supplied

MR imaging of recent spinal trauma.

Proper therapeutic management of acute spinal trauma depends considerably on the assessment of the condition of the underlying spinal cord and the relative stability of the surrounding bony architecture. A series of 14 patients who were examined by magnetic resonance (MR) imaging following spinal trauma is presented. Comparison of information gained by MR with that obtained by conventional CT indicates that MR is useful in assessing spinal cord compression, traumatic disk pathology, and post-traumatic intramedullary abnormalities. Computed tomography is more accurate in detecting posterior neural arch fractures and in assessing the number of displaced fragments.

Adolescent↗
PubMedDate not supplied

Latex protein: a hidden "food" allergen?

Avoidance of latex allergens is the primary method to prevent adverse reactions. Natural rubber latex is found in many different products in both the health care industry and in modern society, and consequently results in unexpected exposures of sensitized individuals. The use of latex gloves by food handlers provides one potential route for inadvertent exposure to latex allergens. In this study we have used two immunological methods to determine whether latex proteins are transferred to foods following contact with latex gloves. Direct transfer of latex protein to cheese was visualized using a modified immunoblot method. Sliced cheese was touched with a gloved finger. A nitrocellulose membrane was applied to lift the potential fingerprints and a rabbit anti-latex antiserum was used to visualize the transfer of any latex finger-prints. After handling lettuce with gloves, transferred protein was recovered by extracting the lettuce and quantified using an inhibition ELISA for latex proteins. Fingerprints of latex protein were readily detectable on cheese after contact with powdered latex gloves, but not with vinyl gloves. Furthermore, powdered latex glove use resulted in measurable amounts of latex protein on lettuce with an exposure-dependent increase in the latex protein levels. Lettuce alone or lettuce handled with vinyl gloves was negative for latex protein. The use of latex gloves by food handlers is the source of an indirect food additive in the form of latex proteins. It is recommended that food handlers avoid the use of latex gloves to eliminate inadvertent exposure of latex-sensitive individuals.

Adult↗
PubMedDate not supplied

Craniopharyngioma: CT and MR imaging in nine cases.

Magnetic resonance (MR) imaging and CT examinations were performed in nine patients with surgically proven craniopharyngioma. Computed tomography was found to be superior to MR in detection of calcification and cyst formation. Extent of involvement of adjacent structures (e.g., optic chiasm, third ventricle, and intracavernous carotid artery) was more clearly delineated by MR. Craniopharyngioma fluid collections were found to be uniformly bright on T2-weighted sequences. However, on T1-weighted sequences, the signal intensity of the fluid ranged from hypointense to hyperintense, reflecting the heterogeneous contents of cysts in these tumors. Since calcification and cyst formation are hallmarks of craniopharyngiomas, we believe that CT is more specific than MR in diagnosis of craniopharyngiomas. Magnetic resonance, however, offers a more accurate assessment of the tumor extent.

Adolescent↗
PubMedDate not supplied

Dyke Award. Evaluation of contrast-enhanced MR imaging in a brain-abscess model.

An alpha-streptococcus brain abscess was produced in five dogs and studied with magnetic resonance (MR) imaging (0.5 T) and computed tomography (CT). Non-contrast- and contrast-enhanced CT scans were obtained using gadolinium diethylenetriamine-pentaacetic acid (Gd DTPA) for MR imaging and meglumine iothalamate for CT scanning. Each animal was evaluated in the early and later cerebritis stages of abscess evolution. On MR, the area of cerebritis enhanced after administration of Gd DTPA in a manner similar to that observed with contrast-enhanced CT. However, contrast enhancement was greater on the MR examination. Early lesions in two animals were detected only with contrast-enhanced MR imaging. This experience suggests that intravenously administered agents such as Gd DTPA should increase the diagnostic potential of MR imaging in neurologic diseases, especially those altering the blood-brain barrier.

Animals↗
PubMedDate not supplied

Neuroradiologic applications of intraarterial digital subtraction angiography.

In the neuroradiologic evaluation of 118 patients using intraarterial digital subtraction angiography definite advantages and disadvantages were defined. Advantages include reduction of contrast medium volume, catheter time, and patient risk and discomfort. It also aids in angiographic planning. The paramount disadvantage is less spatial resolution compared with conventional film angiography.

Aged↗
PubMedDate not supplied

Salicylate removal during plasma exchange in normal volunteers.

The removal of salicylate by plasma exchange in normal subjects was studied. Six healthy men volunteers were given aspirin 975 mg every six hours for five days before undergoing plasma exchange. Blood samples for determination of serum salicylate concentrations were obtained from each subject before the 0730 aspirin dose on study days 3-6 and at hourly intervals for several hours before and after plasma exchange, which was performed at approximately 1500 on study day 5. Blood cell counts, serum albumin concentrations, and other blood chemistry values were also evaluated. Salicylate concentrations in serum and in plasma removed by exchange were determined spectrophotometrically. In each subject, serum salicylate concentrations before and after plasma exchange were compared, as were total area under the serum concentration-time curve and salicylate clearance on and off plasma exchange. The mean trough salicylate concentration at 1930 after plasma exchange on day 5 was significantly lower than the mean trough concentration at 1330 before plasma exchange on the same day. The mean AUC during the six-hour period in which plasma exchange occurred was significantly smaller than the AUC in the six-hour period before plasma exchange. Serum albumin concentrations decreased by a mean of 1.7 g/dl as a result of plasma exchange; however, the mean +/- S.D. amount of salicylate removed was only 191.0 +/- 52.4 mg. The amount of salicylate removed by plasma exchange in this study does not appear to be clinically important.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Antihypertensive effect of hydrochlorothiazide administered once or twice daily.

The antihypertensive effect of once and twice daily hydrochlorothiazide administration was compared in 24 ambulatory patients with essential hypertension. Hydrochlorothiazide 100 mg daily taken as a single morning dose or as a twice daily divided dose was administered to 24 previously diagnosed hypertensive patients in a double-blind cross-over fashion for 12 weeks. No patient received other antihypertensive agents or medications known to influence blood pressure. Sitting and standing blood pressure, weight, pulse, tablet count, and subjective complaints of side effects were obtained at study weeks 3 and 6 on each treatment schedule. There was no significant difference between the mean sitting systolic (133 and 131 mm Hg) or diastolic (85 and 84 mm Hg) blood pressure measurements at study weeks 3 and 6 for each treatment schedule. Comparison of standing mean systolic and diastolic blood pressure and mean arterial pressure produced similar results. Subjective complaints of medication side effects, including orthostasis or urinary frequency, did not differ between treatment schedules. This study suggests that hydrochlorothiazide may be effectively administered once daily for the treatment of hypertension.

Adult↗