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Biomedical subjects

A L Williams

Publications and source records attributed to A L Williams.

At least 19 recordsLinked to original sources
PubMed1979

Computed tomography in Behçet disease.

In Behçet disease, CT may demonstrate low attenuation mass lesions with or without contrast enhancement. Since neurologic involvement may precede the typical dermatologic manifestations, Behçet disease should be included in the differential diagnosis of intracranial mass lesions. A case is presented with central nervous system involvement.

Adult↗
PubMed1979

The computed tomographic appearance of the normal pituitary gland and pituitary microadenomas.

With the use of axial and coronal computed tomography (CT), the authors compared the density, contrast enhancement, and dimensions of normal pituitary glands and pituitary microadenomas. The normal gland appears homogeneous, nearly isodense with brain tissue, and it enhances uniformly. Its upper surface is concave downward or flat and its height 2-7 mm. The cavernous sinuses, the third, fourth, and sixth cranial nerves, the infundibulum, and the adjacent carotid arteries are well demonstrated by CT. Abnormal height and upward convexity of the gland are reliable signs of prolactinoma; abnormal density and enhancement are suggestive signs. CT findings in prolactin- and ACTH-secreting tumors may differ. CT is more sensitive and more specific than polytomography in the diagnosis of pituitary adenoma.

Adenoma↗
PubMed1979

Arteriovenous malformation simulating a cyst on computed tomography.

Three cases are described in which an intracerebral arteriovenous malformation (AVM) was accompanied by a cystic component probably resulting from hemorrhage. The 3 patients gave a history of headaches. In cases of low-attenuating nonenhancing CT processes, an AVM must be considered.

Adult↗
PubMed1979

CT detection of demyelinated plaques in multiple sclerosis.

CT images and anatomic slices of two brains containing numerous demyelinated plaques were correlated. Demyelinated plaques smaller than 0.7 cm were not detected by CT. Some larger plaques were misinterpreted as normal structures. These and other considerations suggest that chronic cerebral demyelination cannot be excluded by negative nonenhanced CT scan.

Brain↗
PubMed1979

CT resolution and diagnostic accuracy.

To justify CT purchases and document certificates of need, the clinical effectiveness of CT scanners with different cost and resolution must be compared. The diagnostic accuracy and anatomic detail in three scanners with different resolution were studied. Seventeen patients were studied with both a first or a second generation CT scanner and a third-generation scanner. Appearance of normal and pathologic structures was compared. Cerebral sulci, corticomedullary discrimination, basal cistern vessels, and some pathologic lesions were seen in third generation images that were not seen in the others. Higher resolution scans provide significantly better anatomic detail and accuracy in detecting pathologic processes.

Adolescent↗
PubMed1978

Synthesis and activities of branched-chain aminoacyl-tRNA synthetases in threonine deaminase mutants of Escherichia coli.

Valyl-, isoleucyl-, and leucyl-tRNA synthetase activities were examined in an Escherichia coli K-12 strain that possessed a deletion of three genes of the ilv gene cluster, ilvD, A, and C, and in a strain with the same deletion that also carried the lambdadilvCB bacteriophage. It was observed that the branched-chain tRNA synthetase activities of both strains were considerably less than those of the normal strain during growth in unrestricted medium. Furthermore, during an isoleucine limitation, there was a further reduction in isoleucyl-tRNA synthetase activity and an absence of the isoleucine-mediated derepression of valyl-tRNA synthetase formation in both of these mutants, as compared with the normal strain. In addition, it was observed that these branched-chain synthetase activities were reduced in steady-state cultures of several ilvA point mutants. However, upon the introduction of the ilv operon to these ilvA mutants by use of lambda bacteriophage, there was a specific increase in the branched-chain synthetase activities to levels comparable to those of the normal strain. These results support our previous findings that the stability and repression control of synthesis of these synthetases require some product(s) missing in the ilvDAC deletion strain and strongly suggest this component is some form of the ilvA gene product, threonine deaminase.

Amino Acyl-tRNA Synthetases↗
PubMed1978

Ineffectiveness of prophylactic intrathecal methylprednisolone in myelography with aqueous media.

The effectiveness of prophylactic intrathecal methylprednisone (MP) in preventing arachnoiditis from iocarmate myelography was studied. Monkeys were injected intrathecally with locarmate, MP, or a combination of the two. Twelve weeks later the severity of arachnoiditis was determined in each animal. There was no significant prophylactic effect of intrathecal MP on arachnoiditis from locarmate. Some arachnoiditis was found in control animals treated with MP alone.

Animals↗
PubMed1978

A myelographic technique for cysts in the spinal canal and spinal cord.

A collapsing cord in six patients with hydromyelia and a collapsing intraspinal arachnoid cyst in one patient are demonstrated. The authors describe the technique for two-position gas myelography and demonstrate that both intra- and extra-medullary intraspinal processes may collapse during myelography.

Adolescent↗
PubMed1977

HLA and the sudden infant death syndrome.

HLA phenotypes of 66 parents of 33 infants succumbing to the sudden infant death syndrome (SIDS) were determined using a standard microlymphocytotoxicity method. Heterogeneity testing over all locus antigens revealed a significant difference between the parents and a control group consisting of blood donors and healthy unrelated volunteers. This heterogeneity was still evident when maternal and paternal groups were considered separately with the controls and when compared with each other. Individual A locus antigens displaying frequency deviation from control values included A9 (decreased in husbands), A10 (increased in wives and total parent group), and A28 (increased in wives). The increase in frequency of A10 became highly significant when only parents of children with evidence of laryngitis at post mortem were used for comparison with control values. No difference in B locus antigens between any of the groups was observed. The results obtained are compatible with the view that SIDS is the result of a hypersensitivity reaction to one or more allergens and that genes coding for these specific responses are linked to the HLA complex. Differences observed between the maternal and paternal groups may be explained on the basis of maternal antibody, passively acquired by the infant, which serves a protective role in the respiratory tract, prior to the development of immunocompetence. The production of these antibodies is also dependent on genes linked to the maternal HLA complex.

Female↗