Biomedical subjects
R Benjamin
Publications and source records attributed to R Benjamin.
Ocular defects in cerebral palsy.
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Magnetic resonance imaging of malignant fibrous histiocytoma.
The magnetic resonance imaging (MRI) changes in 39 patients with malignant fibrous histiocytoma (MFH) were reviewed retrospectively. Twenty-one sarcomas were in the lower extremity, five each in the upper extremity and trunk, two each in the neck and heart, and one each in the maxillary sinus, sella turcica, tongue, and spermatic cord. The examinations were performed with spin-echo sequences on a 1.5 Tesla Signa Scanner (GE, Milwaukee WI). Twenty-two tumors exhibited intermediate signal intensity on T1-weighted images and 23 were of high signal intensity on T2-weighted images. There was no significant differences in signal intensity of 12 preoperative and 13 recurrent neoplasms. Twelve of 13 patients were correctly diagnosed as having postoperative changes. The MR sensitivity and specificity for detecting a neoplasm were 96% and 83% respectively, but the signal changes were nonspecific for MFH. When compared to CT in 14 patients, MR better defined the extent of the MFH, its relationship to surrounding tissues and vessels, and best differentiated residual or recurrent disease from postoperative changes when examined at least 3 months after surgery.
Malingering with AIDS.
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Identification of HIV-infected transfusion recipients: the utility of crossreferencing previous donor records with AIDS case reports.
An expanded "look-back" program has been developed, in which patients who may have been exposed to HIV through blood transfusion were identified via three triggers: the blood that they received was donated by persons who 1) have subsequently been reported to local health departments as meeting the diagnostic criteria for AIDS, 2) have donated since the introduction of anti-HIV screening and tested positive, or 3) have been found to be infected during investigation of reported transfusion-associated HIV infections. In comparing triggers, cross-referencing the list of patients reported to have AIDS (AIDS case list) proved to be the most efficient approach for identifying HIV-infected donors and transfusion recipients. Of the 7973 AIDS patients reported in eight Northern California counties as of December 1988, 316 (4.0%) were determined to have donated at Irwin Memorial Blood Centers between 1977 and 1985. Despite the logarithmic increase in reported cases of AIDS in the San Francisco Bay area over the last 5 years, the rate of detection of previous donors from AIDS case lists remained between 3.3 and 5.4 percent. These persons accounted for 69 percent of the identified infected donors, and their identification led to notification of 60 percent of potentially exposed recipients and 51 percent of known infected recipients. The crossreferencing of AIDS case listings with blood bank records was equally efficient for regions with low and high AIDS prevalence. National adoption of AIDS case list crossreferencing is recommended as an effective means of identifying previously unidentified infected recipients in an effort to limit the secondary spread of HIV infection.
Effect of the substitution of critical residues on the allorecognition of HLA-B27.
The three-dimensional structure of the HLA class I molecules has highlighted the importance of the "groove" formed by the helices. We used site-directed mutagenesis to construct a series of HLA-B27 mutants with different substitutions at the sites of the conserved amino acid residues of HLA-B27 subtypes, specifically residue 77 which is thought to be critical to the binding site of the molecule, and a residue at the CD8 binding site. We formed an anti-B27 CTL line and derived six anti-B27 clones. Each of the six clones showed a different pattern of reaction, reflecting the diversity of the epitopes recognized. All nine mutants were effective in altering allorecognition by HLA-B27 specific CTL, although positions 45 and 77 caused the most drastic effect. The residue in position 77 is also the last amino acid of the peptide sequence shared with Klebsiella. Our results highlight the importance of certain epitopes in allorecognition that may have important implications for the immunotherapy of autoimmune diseases.
Aberrant oncogene expression in uncultured human sarcoma and melanoma.
Protooncogenes have the ability to induce and/or maintain the transformed state when they are overly expressed or altered by mutation or gene rearrangement. To study the possible involvement of these cellular oncogenes in the neoplastic transformation, we have analyzed their expression in 44 fresh samples obtained from primary, recurrent, or metastatic tumors from patients with a variety of sarcomas and a melanoma. Our analysis was carried out by the northern blot technique using poly (A)+ RNA hybridized with human cellular DNA probes. A normal 2.3-kb c-myc transcript was observed almost universally at various levels. A normal c-k-ras transcript of 5.2-kb was detected at a low level in most of the samples. In three samples we detected aberrant c-k-ras transcripts of 7.0 and 8.5-kb, while in two other samples we found an aberrant lower-molecular-weight transcript of 1.4-kb. N-myc was expressed in only three samples, and in all instances, the transcripts were aberrant (more than 10-kb). A normal 3.7-kb c-sis transcript was expressed at a low level in most of the sarcomas and the melanoma but was uniquely overexpressed in giant cell tumors of bone. C-fos (2.2-kb) was expressed at a low level in almost half of the samples; c-myb was never expressed. We conclude that c-k-ras, n-myc, c-sis, and c-myc are aberrantly or overexpressed in sarcoma/melanoma, and their activation may play a role in the transforming events leading to development and/or progression of these tumors.
Rubidazone in adults with previously treated acute leukemia and blast cell phase of chronic myelocytic leukemia: a Southwest Oncology Group Study.
Rubidazone, a new anthracycline antibiotic, is the benzoyl hydrazone derivative of daunorubicin. The Southwest Oncology Group carried out a phase II study of the drug in 126 patients with previously treated acute leukemia; 116 patients were evaluable. Good-risk patients were given doses of 450 mg/m2, and poor-risk patients were given doses of 300 mg/m2 approximately every 3 weeks. No complete response was observed in 25 patients with chronic myelocytic leukemia blast cell transformation. In the remaining patients the overall complete response rate was 22% and the rate of complete plus partial response was 29%. In good-risk patients these rates were 27% and 35%, respectively. Toxicity was similar to that observed with other anthracyclines except that acute febrile reactions were more pronounced. On the basis of the results, there are plans for a large-scale comparison study of rubidazone versus doxorubicin, each in combination with cytarabine, vincristine, and prednisone.