Dose reduction in computerized tomography.
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Radiation Dosage↗
Biomedical subjects
R Gordon
Publications and source records attributed to R Gordon.
The effect of certain variables on the tumor and tissue distribution of tracers. II. Carrier effect: rapidity of onset and concentrations necessary for initiation and maximum response.
The smallest quantity of carrier Ga and Mn necessary to initiate and maximize a carrier effect was studied in the Morris 7777 rat hepatoma model. The quantity needed for a maximum response did not appear to adversely effect the rats. Not all tissues were equally affected at the same plasma concentrations. If carrier Ga was administered 2 hours following 67Ga injection and the rats sacrificed 30 minutes later, a dramatic change occurred in background activity, which was more pronounced in healthy than malignant tissues. Early viable and nonviable tumor/background ratios were improved by this technique. The data suggest that the use of carrier Ga and Mn might improve early lesion/background ratios in patients. This could be of use if tumor imaging were undertaken with 68Ga or 52mMn with positron detector systems.
Animals↗
The effect of certain variables on the tumor and tissue distribution of tracers. III. Salicylates and vasoactive drugs.
Attempts were made to increase the viable tumor concentration of 54Mn and 67Ga in a rat hepatoma model by administering rat angiotensin, tolazoline, and salicylates. Salicylates increased the tumor concentrations of 54Mn and improved 65Mn viable tumor/background ratios. 67Ga was not affected by the salicylates. The salicylate effect appeared to be mediated by intracellular mechanisms rather than alterations in plasma protein binding. Rat angiotensin slightly increased the concentrations of 67Ga in the tumors but not enough to suggest that it would be useful clinically. Tolazoline did not increase tumor uptake of the tracers.
Animals↗
The effect of certain variables on the tumor and tissue distribution of tracers. IV. False carriers: ferric citrate.
The intravenous administration of Fe+3 -citrate (1.6 mg/kg body weight) was demonstrated to alter the concentration of carrier-free 67Ga and 54Mn in malignant and healthy tissues of the rat, Morris 7777 hepatoma model. When the Fe+3 was injected 2 hours before, simultaneously with, or 2 hours after 67Ga (and the rats sacrificed 4 hours after injection), the 67Ga in most normal tissues decreased, and the viable tumor concentrations increased by 135, 24, and 47%, respectively. Twenty-four hours after a simultaneous administration of Fe+3 and 67Ga, egress of 67Ga from the tumor was much less than from the healthy tissues. These changes resulted in significant improvements in viable tumor to background ratios, especially at 4 hours. These changes induced in the distribution of the two tracers by Fe+3 indicate that some kinetic characteristics are shared. This is discussed in the light of their response to carrier Ga and Mn. The use of Fe+3 shows promise as a means of improving tumor/background ratios for 68Ga and 52mMn, two short-lived positron emitters that can be used with positron scanners. Gallium-67 imaging may also be improved by these techniques. The Fe+3 increases excretion of 67Ga from the animal, and this could result in a lower radiation dose to a patient.
Animals↗
Different allelic patterns at chromosome 11q13 in paired aldosterone-producing tumours and blood DNA.
1. We previously reported loss of heterozygosity (LOH) at region q13 of chromosome 11 in five aldosterone-producing tumours (APT) using restriction fragment length polymorphism (RFLP) analysis, including two from patients with familial hyperaldosteronism. 2. In the present study, microsatellite markers were used to examine 33 informative paired blood and tumour DNA samples from patients with APT for LOH at three loci that map to chromosome 11q13. 3. LOH at one or more loci was detected in seven (21.2%) tumour DNA samples. 4. This study provides further support that mutations at 11q13 may be involved in the underlying pathophysiology of aldosterone-producing tumours of the adrenal cortex.
Adrenal Cortex Neoplasms↗
Interaction of felbamate with several other antiepileptic drugs against seizures induced by maximal electroshock in mice.
The anticonvulsant effects of felbamate (FBM) alone or in combination with phenytoin (PHT), carbamazepine (CBZ), valproate (VPA), or phenobarbital (PB) were investigated against maximal electroshock (MES) seizures in mice. Nonprotective doses of the prototype antiepileptic drugs (AEDs) enhanced the protective effects of FBM against electrically induced seizures, as shown by significant reduction of FBM ED50 values. Toxicity as determined by rotorod test was not significantly potentiated, however, and the protective index (PI = TD50/ED50) of FBM was increased by > 100% for each AED interaction. The increase in anticonvulsant potency of FBM after its combination with nonprotective doses of AEDs could not be accounted for by a pharmacokinetic mechanism.
Animals↗
Computed tomography from ordinary radiographs for teleradiology.
Computed tomography (CT) can be achieved inexpensively using ordinary x-ray equipment available at most primary health care centers. We present here the techniques and initial results of experiments with an overhead x-ray unit and film as means for collecting projection data for CT. Our algorithms include standard ART (algebraic reconstruction technique) and modifications we have derived to prevent streaking artifacts due to the use of a small number of views, and to correct geometric distortion due to limited angular coverage. Our methods enable remote computed tomography via teleradiology.
Technology, Radiologic↗
Combining multiple-imaging techniques for in vivo pathology: a quantitative method for coupling new imaging modalities.
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Magnetic Resonance Spectroscopy↗
Obstruction of the right ventricular outflow tract due to metastatic hypernephroma.
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Adenocarcinoma↗
Different training procedures recruit either one or two critical periods for contextual memory consolidation, each of which requires protein synthesis and PKA.
We have used a combined genetic and pharmacological approach to define the time course of the requirement for protein kinase A (PKA) and protein synthesis in long-term memory for contextual fear conditioning in mice. The time course of amnesia in transgenic mice that express R(AB) and have genetically reduced PKA activity in the hippocampus parallels that observed both in mice treated with inhibitors of PKA and mice treated with inhibitors of protein synthesis. This PKA- and protein synthesis-dependent memory develops between 1 hr and 3 hr after training. By injecting the protein synthesis inhibitor anisomycin or the PKA inhibitor Rp-cAMPs at various times after training, we find that depending on the nature of training, contextual memory has either one or two brief consolidation periods requiring synthesis of new proteins, and each of these also requires PKA. Weak training shows two time periods of sensitivity to inhibitors of protein synthesis and PKA, whereas stronger training exhibits only one. These studies underscore the parallel dependence of long-term contextual memory on protein synthesis and PKA and suggest that different training protocols may recruit a common signaling pathway in distinct ways.
Acoustic Stimulation↗
The emergence of emergence: a critique of "design, observation, surprise!".
Artificial life research begins from the premise that Alife subsumes real life. A criterion for emergence in Alife has been formulated that, however, excludes real life and postulates the need for a real life Designer and an Observer. This in effect nullifies the premise of Alife and takes us back to the argument for God from design of Bishop Paley in 1802. An alternative is to realize that Alife could include two properties: simulated organisms that both design themselves and are the observers. Self-design can come about via evolution in a population of mating organisms, especially via mutations that are gene or higher order duplications. Duplications permit novelty while retaining previously attained functions. The ability to observe can itself evolve, if its construction process evolves. This may now be possible to simulate, if new paradigms for embryogenesis, such as positional information or differentiation waves, prove accurate, or at least sufficiently robust to construct a wide diversity of observational abilities. The evolution of perception, however, may be limited by the physics available to the Alife organisms, which can come in three forms: simulated physics, real physics accessible to robots, or "Cyberspace physics".
Computers↗
Hormone stimulation and chemotherapy in advanced prostate cancer: preliminary results of a prospective controlled clinical trial.
Preliminary evidence suggests that the sensitivity of endocrine-dependent neoplasms to chemotherapy may be enhanced by transient hormonal stimulation of tumor growth. To test this concept, we are conducting a prospective controlled trial in men with stage D2 prostate cancer who have relapsed following orchiectomy. All patients are continuously treated with aminoglutethimide and hydrocortisone to lower adrenal androgen secretion plus cyclic chemotherapy. Patients in the stimulation arm receive, in addition, the synthetic androgen fluoxymesterone for 3 days before and on the day of chemotherapy. Of 41 patients entered to date, 26 are evaluable. Twenty-one (81%) obtained either an objective remission or stabilization of disease with a mean duration of 9+ months and 10 patients still responding. Thus far, the response rate is similar in the control and stimulation groups. Androgen administration was associated with a rise in acid phosphatase and usually a modest flare of symptoms except for 2 patients who developed spinal cord compression. These preliminary data indicate that the combination of aminoglutethimide and chemotherapy has a potent antitumor effect on advanced prostate cancer refractory to orchiectomy. A large number of patients and a longer follow up are needed to assess whether transient androgen administration potentiates the effect of chemotherapy.
Acid Phosphatase↗
Surgical treatment of a solitary giant hemangioma of the liver presenting as an avascular mass.
A clinically silent giant hepatic hemangioma was diagnosed following, and as a result of, minor trauma. Liver scan, arteriography and liver biopsy were suggestive of an avascular mass, but laparotomy established that the tumor was a hemangioma. Surgical treatment and complete recovery followed. These benign primary hepatic tumors are usually discovered incidentially. Their presentation and management are discussed.
Adult↗
A nursery school in a rehabilitation center.
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Child, Preschool↗
Chest xerotomography: evaluation of calcification within lung nodules.
Through the use of a chest phantom and beeswax nodules containing calcium, xerotomography is shown to be a valuable tool in the evaluation of calcifications within lung nodules. The technique gives superior definition of calcium, especially fine calcifications in the 1-2-mm, or less, range. Our results suggest that clinical trials should follow and clinicopathologic correlation be obtained.
Calcinosis↗
[Nuclear state splitting: a working model for the mechanochemical coupling of differentiation "waves" with the controlling genes (master genes)].
The cell state splitter (CSS) model for differentiation, supported by recent evidence, requires that an intracellular mechanical events result in a commitment signal to the nucleus that determines which of two readied gene cascades is to be activated, via their master genes. We show how a link between the mechanochemistry of cell state splitting and the molecular genetics of "nuclear state splitting" might be forged out of well known molecular components of cells.
Animals↗