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Biomedical subjects

A M Wang

Publications and source records attributed to A M Wang.

At least 73 records · Page 4Linked to original sources
PubMed1987

Modern imaging of the masseter muscle: normal anatomy and pathosis on CT and MRI.

Tremendous advances in diagnostic imaging technology have produced computed tomography (CT) and magnetic resonance (MR) imaging--new ways to depict the normal anatomy and pathosis of the masseter muscle. This article reviews the masseter muscle's normal appearance on CT and MR images and demonstrates the clarity with which CT, in particular, is able to depict soft tissue lesions and neighboring bony involvement. Analysis of the strengths, weaknesses, and availability of these new techniques leads to the conclusion that CT is currently the test of choice for imaging masseteric lesions but that MR shows greater promise for the future.

Adult↗
PubMed1987

Localization of the T4 phage ribonucleotide reductase B1 subunit gene and the nucleotide sequence of its upstream and 5' coding regions.

The nucleotide (nt) sequence in a 757-bp [corrected] segment downstream from the intron-containing T4 phage thymidylate synthase gene (td) has been determined. This region was found to contain two open reading frames (ORFs). The first ORF(ORF2) [corrected] 261 bp [corrected] in length, is 24 [corrected] nt downstream from the td gene. The second ORF(ORF3) [corrected]) is 200 bp long at 558 [corrected] nt from the td gene and extends to the end of the Eco RI fragment. The amino acid (aa) sequence (66 aa residues) deduced from the second truncated ORF shows 59% homology to the sequence of the N-terminal portion of the ribonucleotide reductase large subunit of either Escherichia coli (B1 subunit) or mouse (M1 subunit). This tentatively identifies the truncated gene to be the 5' end of the T4 phage ribonucleotide reductase subunit B1 (nrdA) gene and pinpoints its exact location on the T4 phage genomic map. Southern hybridization analysis suggests good sequence homology among the nrdA genes of various T-even phages.

Amino Acid Sequence↗
PubMed1987

Cutaneous protothecosis. A clinicopathologic study.

In what we believe to be the first case of cutaneous protothecosis identified in Taiwan, a 5-year-old Chinese girl presented with a pruritic erythematous plaque on her right upper eyelid. A clinical diagnosis of eczematous dermatitis was made initially, and sporotrichosis was diagnosed subsequently. Later, histopathologic and cultural studies of the lesion finally led to the diagnosis of protothecosis. The recognition of the characteristic sporangia containing symmetrically arranged endospores is the most important initial diagnostic clue of protothecosis. Biochemical assimilation tests and direct immunofluorescence study using species-specific antibodies identified the organism as Prototheca wickerhamii. Systemic ketoconazole treatment proved to be effective for our patient. The in vitro minimal inhibitory concentrations of tetracycline hydrochloride, amphotericin B, and ketoconazole were also determined.

Biopsy↗
PubMed1986

Malignant mesothelioma with brain metastases.

Although malignant mesothelioma is known to spread hematogenously, brain metastases are rare. In the patient presented herein, multiple unilateral symptomatic central nervous system metastases developed that were diagnosed by computed tomography and documented at autopsy. Since malignant mesothelioma is occurring more frequently in the population at risk (asbestos workers), this complication may be observed more commonly in the future.

Brain↗
PubMed1986

Septation and focal dilatation of ventricles associated with cryptococcal meningoencephalitis.

A 35-year-old woman developed temporal lobe seizures. Isolated dilatation of the right temporal horn was demonstrated by computed tomography. She was asymptomatic for the next 10 months while on anticonvulsants before severe headaches, vomiting, and mental confusion prompted hospitalization. Both temporal horns were now dilated, there was marked periventricular edema, and cryptococci were cultured from the ventricular fluid. She succumbed after prolonged systemic and intrathecal antifungal therapy, having developed isolation and dilatation of both frontal horns and third and fourth ventricles. Cryptococcal or other fungal meningoencephalitis should be considered in the differential diagnosis of isolated dilatations of the ventricular chambers as noted in the present case.

Adult↗
PubMed1986

Balloon occlusion of a recurrent carotid-cavernous fistula previously treated by carotid ligations.

A carotid-cavernous fistula recurred 16 years after a Hamby procedure. The recurrence was manifested by subarachnoid hemorrhage originating from dilated draining pial veins. The fistula was closed with a balloon catheter introduced through a patent remnant of the cervical carotid artery. Patients who have previously undergone Hamby trapping and embolization should be reassessed for an occult fistula that could predispose them to intracranial bleeding.

Adult↗
PubMed1985

Molecular cloning of a complementary DNA encoding human macrophage-specific colony-stimulating factor (CSF-1).

Complementary DNA (cDNA) clones encoding human macrophage-specific specific colony-stimulating factor (CSF-1) were isolated. One cDNA clone codes for a mature polypeptide of 224 amino acids and a putative leader of 32 amino acids. This cDNA, which was cloned in the Okayama-Berg expression vector, specifies the synthesis of biologically active CSF-1 in COS cells, as determined by a specific radioreceptor assay, macrophage bone marrow colony formation, and antibody neutralization. Most of the cDNA isolates contain part of an intron sequence that changes the reading frame, resulting in an abrupt termination of translation; these cDNA's were inactive in COS cells. The CSF-1 appears to be encoded by a single-copy gene, but its expression results in the synthesis of several messenger RNA species, ranging in size from about 1.5 to 4.5 kilobases.

Amino Acid Sequence↗
PubMed1985

Molecular cloning of the complementary DNA for human tumor necrosis factor.

Tumor necrosis factor (TNF) is a soluble protein that causes damage to tumor cells but has no effect on normal cells. Human TNF was purified to apparent homogeneity as a 17.3-kilodalton protein from HL-60 leukemia cells and showed cytotoxic and cytostatic activities against various human tumor cell lines. The amino acid sequence was determined for the amino terminal end of the purified protein, and oligodeoxyribonucleotide probes were synthesized on the basis of this sequence. Complementary DNA (cDNA) encoding human TNF was cloned from induced HL-60 messenger RNA and was confirmed by hybrid-selection assay, direct expression in COS-7 cells, and nucleotide sequence analysis. The human TNF cDNA is 1585 base pairs in length and encodes a protein of 233 amino acids. The mature protein begins at residue 77, leaving a long leader sequence of 76 amino acids. Expression of high levels of human TNF in Escherichia coli was accomplished under control of the bacteriophage lambda PL promoter and gene N ribosome binding site.

Amino Acid Sequence↗
PubMed1985

Intracranial meningioma with abnormal localization of bone-seeking radiopharmaceutical: correlation with gross and microscopic pathology.

Meningioma is one of the neoplasms in which there may be extraosseous localization of bone-seeking radiopharmaceuticals. Tumor calcification, calvarial erosion, and the formation of reactive bone have been proposed as the cause of this abnormal tracer localization. We present a patient with a frontal meningioma that was evaluated using 99mTc-methylene-diphosphonate bone scintigraphy, head computed tomography, and skull radiography; the homogeneous density seen in the radiographic studies corresponded to the area of bone-seeking-agent localization shown in the scintigram. At autopsy, bony tissue and a few psammoma bodies were found in the meningioma, and apparently accounted for the bone-tracer localization. There was no calvarial erosion and no formation of reactive bone. If skull-radiographic studies show a homogeneous, radio-opaque lesion with no reactive changes in the adjacent skull, a meningioma showing a localization of a bone-seeking radiopharmaceutical may be predicted to have bone-tissue formation with or without psammoma bodies.

Aged↗
PubMed1984

Computed tomography and conventional radiographs of the craniocervical region in rheumatoid arthritis. A comparison.

Radiographs and computed tomography (CT) scans of 12 patients with rheumatoid arthritis of the cervical spine were reviewed to determine whether CT provides additional information to that obtained from conventional radiography and tomography. Modalities were compared with respect to determination of the extent of erosion, C1-C2 subluxation, atlantoaxial impaction, and soft tissue findings. CT showed greater extent of erosion in 9 of 12 patients. In 11 patients with C1-C2 subluxation, CT and plain radiographs were both useful because it was necessary to demonstrate both sagittal and axial relationships. In the 5 patients with atlantoaxial impaction both CT and plain radiographs demonstrated the abnormal relationships between the odontoid and the foramen magnum. CT showed attenuation of the transverse ligament and the presence or absence of spinal cord compression, whereas plain radiographs did not. Nevertheless, significant new information regarding the spinal cord was obtained by CT in only 1 of the 12 patients. Computed tomography provides additional information about the rheumatoid cervical spine that is unobtainable by conventional modalities. In particular, CT demonstrates bone changes in the axial projection and facilitates evaluation of soft tissue, ligament, and spinal cord involvement. However, CT should be reserved for those instances in which plain radiographs and tomograms do not explain clinical findings.

Aged↗
PubMed1984

Case of the season.

Explore the source record for details and available documents.

Cranial Nerve Neoplasms↗
PubMed1984

Spinal cord or nerve root compression in patients with malignant disease: CT evaluation.

Fifty patients with malignant disease were seen on an emergency basis because they showed clinical signs of spinal cord or nerve root compression. All were studied with high resolution computed tomography (CT) of the spine; in addition, myelography was performed on 10 of the patients. We found that 48 cases (96%) could be accurately diagnosed by CT alone. In two cases (4%) CT was inconclusive, but myelography was diagnostic; one proved to be cerebrospinal fluid seeding with nerve root involvement, and the other showed conus medullaris involvement. In the remaining eight cases studied by both techniques, correlation between CT and myelography was very good.

Adult↗
PubMed1984

Cervical chordoma presenting with intervertebral foramen enlargement mimicking neurofibroma: CT findings.

A cervical chordoma, confirmed at surgery, presented on plain spine films as a focal enlargement of the intervertebral foramen and mimicked the characteristic appearance of cervical neurofibroma. Computed tomography (CT) of the cervical spine was obtained immediately following metrizamide myelography; it demonstrated a soft-tissue mass in the enlarged intervertebral foramen that extended posteriorly to compress the spinal cord and anteriorly to compress the hypopharynx. The mass was sharply demarcated, inhomogeneous, and low in attenuation; CT density measured between those of cerebrospinal fluid and muscle. Although this CT appearance is not specific for cervical chordoma, it is unusual for neurofibroma. Cervical chordoma should be considered in the differential diagnosis of focal enlargement of cervical intervertebral foramina.

Adult↗
PubMed1984

Posterior fossa ependymal cyst and atlantoaxial subluxation in a patient with Down syndrome: CT findings.

A 61-year-old woman with Down syndrome presented with progressive deterioration of gait over 9 months. Cranial CT without and with intravenous administration of contrast material demonstrated a posterior fossa cyst. The cyst did not communicate with the fourth ventricle or subarachnoid spaces as proven by CT following a metrizamide ventriculogram. Surgical fenestration of the cyst into the fourth ventricle was done. In addition, a moderate atlantoaxial subluxation with 2 mm movement from extension to flexion was present, which was thought not to be clinically significant, but which might require a spinal fusion at a future time. Ependymal cells were found as a result of a biopsy of the cyst wall.

Atlanto-Axial Joint↗