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L Chiu

Publications and source records attributed to L Chiu.

12 recordsLinked to original sources
PubMed1992

Cognition and the corpus callosum: verbal fluency, visuospatial ability, and language lateralization related to midsagittal surface areas of callosal subregions.

Normal volunteers (28 women), 20-45 years old, completed tests of visuospatial ability, verbal fluency, and language lateralization, and the midsagittal surface areas of the splenium, isthmus, midregion, and genu of the corpus callosum were measured from inversion recovery magnetic resonance images. Multivariate statistics were used to analyze patterns of correlations. Verbal fluency correlated positively with the area of the splenium and with the area of a posterior callosal factor defined largely by the splenium. The posterior callosum, particularly the splenium, also correlated negatively with language lateralization. There were no other consistent brain-behavior relationships. These results are relevant to understanding factors involved in the development of cognitive characteristics that show sex differences and to understanding the neural basis of language lateralization and verbal abilities.

Adult↗
PubMed1991

Spurious hyperkalaemia associated with severe thrombocytosis and leukocytosis.

A patient with marked thrombocytosis and leukocytosis associated with myelofibrosis was found to have spurious hyperkalaemia caused by in vitro cell lysis. Initial failure to recognize the cause of the hyperkalaemia led to an inappropriate and potentially harmful intervention in an effort to optimize the patient's preoperative status.

Aged↗
PubMed1991

Transport of asparagine by rat brain synaptosomes: an approach to evaluate glutamine accumulation.

Isolated rat brain synaptosomes accumulated L-asparagine with a Km value of 348 microM and a Vmax value of 3.7 nmol/mg of protein/min at 28 degrees C. Uptake of L-asparagine was inhibited by the presence of L-glutamine, whereas transport of L-glutamine was blocked by L-asparagine. Alanine, serine, cysteine, threonine, and, in particular, leucine were also inhibitory whereas alpha-(methylamino)isobutyrate, ornithine, lysine, arginine, and glutamate were much less effective blockers. Transport of L-asparagine had a substantial sodium-dependent component, whereas that of the D-stereoisomer was almost unaffected by the presence or absence of the cation. L-Asparagine was accumulated to a maximal gradient, [L-Asn]i/[L-Asn]o, of 20-30, and this value was reduced to 5-6 by withdrawal of sodium or addition of high [KCI]. A plot of log [Na+]o/[Na+]i against the log [L-Asn]i/[L-Asn]o had a slope close to I, which indicates that a single sodium ion is transported inward with each asparagine molecule. It is postulated that uptake of L-asparagine occurs, to a large extent, in cotransport with Na+ and that it utilizes the sodium chemical gradient and the membrane electrical potential as the source of energy. The similarity between the L-asparagine and L-glutamine transport systems and the reciprocal inhibition of influx of the two amino acids suggest that the same mechanism is responsible for glutamine accumulation. This could explain the high [Gln]i maintained by the brain in vivo.

Amino Acids↗
PubMed1990

In vivo moment arm calculations at the ankle using magnetic resonance imaging (MRI).

In vivo moment arm lengths for the Achilles tendon and tibialis anterior (TA) were determined in 10 adult male subjects. Moment arms were measured as the perpendicular distance between the joint center of rotation (CR) and the center of the muscle's tendon on a series of sagittal plane magnetic resonance images. The first set of calculations used a fixed CR and the second a moving CR. The position of the CR was determined using a modification of the graphical method of Reuleaux. For both moving and fixed CR conditions, moment arms increased by approximately 20% for the Achilles tendon and decreased by approximately 30% for the TA when the ankle moved from maximum dorsiflexion to maximum plantarflexion. Moment arms averaged 3.1% greater for the Achilles tendon and 2.5% greater for the TA when calculated using a fixed CR. These data suggest that the averaged moment arm lengths for the Achilles tendon and the TA were relatively unaffected by the use of a fixed vs moving CR.

Achilles Tendon↗
PubMed1990

MRI and diabetic foot infections.

The role of magnetic resonance imaging and plain radiographs in evaluating osteomyelitis in the diabetic foot was studied. Fifty patients were prospectively examined by magnetic resonance imaging and plain radiographs to determine the extent of infection. Thirty-seven patients had positive MRI for osteomyelitis and 19 were positive with conventional radiography. Thirteen patients had negative MRI healed with short course of antibiotics. Five patients with positive MRI received four weeks' course of intravenous antibiotics with two still having persistent infection in the six weeks follow-up. Thirty-two patients underwent surgery with favorable results. Sixty-two bone specimens were obtained for histologic evaluation of osteomyelitis. In cases with histologic proof of diagnosis, magnetic resonance sensitivity was 99%, specificity was 81%, and accuracy was 94%. Thus magnetic resonance imaging was shown to have a high sensitivity, specificity, and accuracy in detecting osteomyelitis.

Adult↗
PubMed1987

Hemangiomas of skeletal muscle: MR findings in five patients.

Skeletal muscle hemangiomas are uncommon tumors of young adults. More than 90% are misdiagnosed preoperatively. Plain-film examinations, bone scans, CT studies, and angiography may not always be specific for this tumor. Seven MR examinations were performed in five young adult patients with pathologically proved skeletal muscle hemangiomas. All five hemangiomas showed high signal intensity on both T1- and T2-weighted images. The signal intensity in these tumors was less than that of subcutaneous fat on relatively T1-weighted images and greater than that of fat on relatively T2-weighted images. Four tumors had a serpiginous pattern. Four patients had focal muscle atrophy. Three patients had all three findings (high signal intensity on both T1- and T2-weighted images, serpiginous pattern, and associated focal muscle atrophy) while the other two patients had at least two of the three findings. These three patients did not undergo angiography or needle biopsies before surgery because the MR findings were highly suggestive of hemangioma. Our experience with this small series of patients suggests that skeletal muscle hemangiomas have a consistent appearance on MR. MR may be able to contribute significantly to the preoperative diagnosis of this tumor and may also supply valuable information about the extent of the lesion.

Adolescent↗
PubMedDate not supplied

MR compatible winged infusion set.

Winged infusion sets are useful for short term venous infusion in a variety of applications and may be used without problem during CT scanning, ultrasound, or most other medical imaging applications. Drawbacks of using these standard winged infusion sets during MR scanning are torque and imaging artifacts. We describe a new MR compatible infusion set that overcomes these problems.

Equipment Design↗
PubMedDate not supplied

MR of hemorrhagic acoustic neuromas.

The magnetic resonance (MR) appearance of hemorrhagic acoustic neuromas has not previously been reported. Four patients with surgically proven acoustic neuromas containing spontaneous hemorrhage were preoperatively evaluated with MR imaging. All patients presented with new onset of symptoms and three had subarachnoid hemorrhage. Signal changes on T1- and T2-weighted spin echo sequences were characteristic for acute, subacute and chronic intraparenchymal hemorrhage. Recognition of hemorrhagic changes on MR is important since more rapid surgical intervention is required in this patient subgroup.

Adult↗
PubMedDate not supplied

MR findings in extracranial cysticercosis.

A patient with disseminated cysticercosis involving orbit, tongue, parotid glands, epicardial fat, muscle, and subcutaneous tissues is presented. Magnetic resonance findings are described with emphasis on intraorbital and extracranial lesions.

Adult↗