Biomedical subjects
G Simmons
Publications and source records attributed to G Simmons.
Radioimmunodetection of cancer with radiolabeled antibodies to alpha-fetoprotein.
Sixteen patients with histologically proven malignant neoplasia were investigated by radioimmunodetection, using goat anti-alpha-fetoprotein (AFP) antibody radiolabeled with 131I. Images of the chest and abdomen were made with a scintillation camera, usually at 24 and 48 hr following injection of 1 to 2.5 mCi of radioiodinated antibody. Computer-assisted processing for the subtraction of 99mTc background radioactivity was used to enhance the detection and localization of tumors visualized by immune scintigraphy. All 12 sites involved by five AFP-producing tumors could be demonstrated by radioimmunodetection, while normal goat immunoglobulin G labeled with 131I failed to show similar results in one of the patients in whom the radioactive AFP antibody achieved tumor radiolocalization. Five patients in whom the tumors were not expected to produce AFP also had their large tumors demonstrated by immune scintigraphy in 6 of 16 tumor sites. The average tumor to non-tumor 131I image count density ratios were 3.20 and 1.96 for the AFP-containing and putatively AFP-deficient tumors, respectively. The image contrast was significantly greater for the AFP-containing tumors, and the subtraction technique enhanced the image contrast more than 2-fold. Based upon these initial results, the sensitivity of the method (true-positive rate) was 100%, its specificity (true-negative rate) was 80%, and the accuracy of the technique was 85%. This study thus indicates that radioimmunodetection of cancer with radioactive AFP antibodies can be useful in the evaluation of patients with AFP-containing neoplasms.
Differential accumulation of Tc-99m DTPA and Tc-99m pyrophosphate within cerebral and cranial lesions: concise communication.
We sought to determine the clinical utility of using a bone-scanning agent in addition to a brain-scanning agent for the imaging of cerebral and cranial lesions. Images were obtained in 51 patients with Tc-99m diethylene-triamine-pentacetic-acid (DTPA) followed by Tc-99m pyrophosphate (PPi) within 2--5 days. The scans were qualitatively analyzed and the lesion-to-background count density ratios were determined from the corresponding brain and skull images. Only four of 20 cerebral infarctions were better demonstrated with PPi, whereas they were better with DTPA in 14 patients. They were equally good in two patients. The average lesion-to-background count-density ratio for infarction was 1.555 +/- 0.335 with DTPA and 1.428 +/- 0.573 with PPi (p < 0.05). Primary brain tumors were better visualized with DTPA in four out of five cases (p < 0.05). Metastases to brain showed up better with DTPA in 15 of 16 patients (p < 0.05), whereas all ten metastases to skull were seen better with PPi (p < 0.01). These results support previous reports regarding the radiopharmaceutical of choice for tumor imaging but not for infarction. This may be due to the differences in blood clearance for the various imaging agents.
Imaging approach in radioimmunodetection.
External in vivo imaging of tumors with radioactively labeled antibodies to tumor-associated antigens requires processing to remove interfering nontarget radioactivity. Processing entails the use of simulated nontarget compounds labeled with a radionuclide physically different from that on the antibody and substraction of the simulated nontarget activity from the nontargeted antibody. A 2-fold increase of the target to nontarget radioactivity is achieved that has made possible a greater than 70% tumor detection rate.
Experimental hyphema clearance in rabbits. Drug trials with 1% atropine and 2% and 4% pilocarpine.
The effect of topical 1% atropine sulfate, 2% pilocarpine hydrochloride, and 4% pilocarpine hydrochloride on the clearance rate of RBCs labeled with chromium 51 (51Cr) that were injected into the anterior chamber of rabbits was determined by monitoring sequential radioactivity counts. Counts were made directly over the anterior chamber. One eye of each animal was treated with either 1% atropine, 2% pilocarpine, or 4% pilocarpine, and the other eye served as a control. None of these drugs significantly altered the clearance rate of 51Cr-labeled RBCs injected into the anterior chamber.
A modified FORTRAN program for the calculation of modulation transfer function.
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The dilemma of family planning in a North Indian State.
An empirical study of the family planning program and its clients in the rural areas of Allahabad Division of Uttar Pradesh in India was undertaken in 1971-1972. While family planning acceptance in this region is low, interviews with villagers and family planning staff suggest that organizational shortcomings of the program may help to explain the low level of acceptance. The reported level of contact between the program field staff and the village population was unexpectedly low. The paper discusses a number of administrative problems within the family planning organization, especially at the level of the primary health center. It is concluded that in designing family planning programs, efforts should be made to minimize organizational requirements.
[Community multidisciplinary approach to a particular focus of active pulmonary tuberculosis].
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Impairment of adaptive tolerance to oxygen toxicity by systemic immunosuppression.
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Radiopharmaceutical dosimetry in pediatrics.
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HIV coreceptors, cell tropism and inhibition by chemokine receptor ligands.
HIV is a persistent virus that survives and replicates despite an onslaught by the host's immune system. A strategy for cell entry, requiring the use of two receptors, has evolved that may help evade neutralizing antibodies. HIV and SIV usually require both CD4 and a seven transmembrane (7TM) coreceptor for infection. At least eleven different 7TM coreceptors have been identified that confer HIV and/or SIV entry. For HIV-1, the major coreceptors are CCR5 and CXCR4, while the role of other coreceptors for replication and cell tropism in vivo is currently unclear. Polymorphisms in the CCR5 gene that reduce CCR5 expression levels, protect against disease progression, suggesting that drugs targeted to CCR5 could be effective. Such therapies however will not work if HIV simply adapts to use alternative coreceptors. In the light of these themes, this review will discuss the following topics: (i) the coreceptors used by primary HIV-1 and HIV-2 viruses, (ii) the properties and coreceptors of HIV-2 strains that infect cells without CD4, (iii) the role of coreceptors in HIV cell tropism and particularly macrophage infection and (iv) the properties of chemokine receptor ligands that block HIV infection.
MRI and clinical findings in rhombencephalosynapsis.
Rhombencephalosynapsis is an unusual disorder characterized predominantly by agenesis/hypogenesis of the cerebellar vermis and fusion of the cerebellar hemispheres. Three cases are reported with emphasis on the MRI and clinical findings. Discussion of the relative importance of the cerebellar anomalies and associated supratentorial abnormalities is included.
Radioimmunodetection of cancer: an update.
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