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Biomedical subjects

M C Nelson

Publications and source records attributed to M C Nelson.

At least 19 recordsLinked to original sources
PubMed1993

Partial sequence analysis of 130 randomly selected maize cDNA clones.

As part of a project to identify novel maize (Zea mays L. cv B73) genes functionally, we have partially sequenced 130 randomly selected clones from a maize leaf cDNA library. Data base comparisons revealed seven previously sequenced maize cDNAs and 18 cDNAs with sequence similarity to related maize genes or to genes from other organisms. One hundred five cDNAs show little or no similarity to previously sequenced genes. Our results also establish the suitability of this library for large-scale sequencing in terms of its large insert size, proper insert orientation, and low duplication rate.

Cloning, Molecular↗
PubMed1991

Magnetic resonance appearance of peripheral nerve sheath tumors.

Magnetic resonance imaging (MRI) was used to evaluate 22 histologically proven peripheral nerve sheath tumors, approximately two-thirds of which arose in the lower extremity. The histologic distribution was as follows: 12 schwannomas, 7 neurofibromas, and 3 malignant peripheral nerve sheath tumors (2 of which occurred in patients with neurofibromatosis). Most lesions demonstrated an intermediate to moderately bright signal on T1-weighted images and were minimally inhomogeneous. All lesions were moderately bright on proton-density-weighted images and bright on T2-weighted images, again with variable inhomogeneity. The extent of the tumor was best assessed on proton-density- and T2-weighted images. Smooth margins were noted in 19 lesions. Of the 3 remaining lesions, 2 were malignant (but had been subjected to biopsy prior to MRI), and the other lesion was a plexiform neurofibroma. MRI accurately determined the relationship between the lesion and the adjacent neurovascular structures and muscles, thereby assisting surgical management. On MRI, 5 lesions demonstrated coexistent subtle muscle atrophy along the longitudinal axis of surrounding or distally innervated musculature. This latter finding, together with the presence of a tumor in the vicinity of a large nerve trunk, suggests a peripheral nerve sheath neoplasm.

Adult↗
PubMed1991

Evaluation of the painful shoulder. A prospective comparison of magnetic resonance imaging, computerized tomographic arthrography, ultrasonography, and operative findings.

Twenty-one patients who had had pain in the shoulder for more than three months were evaluated with ultrasonography and magnetic resonance imaging followed by computerized tomographic arthrography. The results of the imaging studies were then compared with the operative findings. Magnetic resonance imaging was found to be the most useful modality for establishment of the etiology of pain in the shoulder due to disease of the rotator cuff, instability associated with abnormality of the glenoid labrum, subacromial impingement, stenosis of the coracoacromial arch, and osteoarthrosis of either the glenohumeral or the acromioclavicular joint. The accuracy of magnetic resonance imaging was found to depend on both the operator and the technique and was decreased in extremely obese patients, due to difficulties in positioning, and in patients who had had a previous operation. Magnetic resonance imaging was more accurate than either computerized tomographic arthrography or ultrasonography in identifying partial-thickness tears (intrasubstance changes in the rotator cuff). Magnetic resonance imaging provided the same level of accuracy as computerized tomographic arthrography in the detection of abnormalities of the glenoid labrum.

Adolescent↗
PubMed1990

Magnetic resonance imaging of peripheral soft tissue hemangiomas.

Ten patients with soft tissue hemangiomas outside the central nervous system were studied with MR imaging. Eight patients were studied at 1.5 Tesla (T) with T1-weighted and triple echo T2-weighted sequences. Two additional patients were imaged on a 0.5-T system. The MR images were correlated with images from other modalities. Histologic diagnosis was obtained in all cases. It was found that prolonged T2-weighted imaging together with standard spin echo T1 and T2 pulse sequences is a good substitute for contrast-enhanced CT and arteriographic evaluation of soft tissue hemangiomas.

Adolescent↗
PubMed1990

Case report 610: Amyloid arthropathy of the left ankle.

In summary, a case of amyloid arthropathy of the left ankle in a 64-year-old patient with multiple myeloma is presented. The asymmetric presentation and site of deposition in the ankle were taken to be unusual. Involvement of both hips and the right shoulder was also suspected on subsequent evaluation. The patient's history and MR studies were essential in establishing the preoperative diagnosis. The extent of involvement, destruction of underlying cartilage, associated effusion and tenosynovitis were optimally defined by the MR images. The MR images also provided preoperative guidance in determining the approach and optimum site of biopsy.

Amyloidosis↗
PubMed1990

The role of MRI in diagnostic imaging of the injured knee.

Clinical evaluation of the acutely injured knee is often supplemented by radiographic studies. Magnetic resonance imaging (MRI) is rapidly replacing other techniques as the study of choice for evaluating knee injuries. MRI can delineate meniscal tears, cruciate and collateral ligament injuries, and tendon, capsule and cartilage problems.

Adolescent↗