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Biomedical subjects

J M Turrel

Publications and source records attributed to J M Turrel.

31 records · Page 2Linked to original sources

Serum thyroxine concentrations after radioactive iodine therapy in cats with hyperthyroidism.

Thirty-one cats with hyperthyroidism were given one dose of radioactive iodine (131I) IV. Serum thyroxine (T4) concentrations were measured before treatment in all cats, at 12-hour intervals after treatment in 10 cats, and at 48-hour intervals after treatment in 21 cats. Serum T4 concentrations also were measured one month after 131I therapy in 29 cats. Activity of 131I administered was 1.5 to 6.13 mCi, resulting in a dose of 20,000 rads to the thyroid. Serum T4 concentrations before 131I administration were 5.3 to 51.0 micrograms/dl, with a median T4 concentration of 11.0 micrograms/dl. Serum T4 decreased most rapidly during the first 3 to 6 days after treatment. Sixteen cats (55%) had normal serum thyroxine concentrations by day 4 after 131I administration, and 23 cats (74%) were euthyroxinemic by day 8 after treatment. One month after administration of 131I, the 29 cats evaluated were clinically improved, and 24 (83%) of the 29 cats evaluated had normal serum T4 concentrations, 3 cats (10%) remained hyperthyroxinemic, and 2 cats (7%) were hypothyroxinemic. Therefore, administration of 131I was a safe and effective method to quickly decrease serum T4 concentrations in hyperthyroid cats.

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Computed tomographic characteristics of primary brain tumors in 50 dogs.

Fifty histologically identified primary brain tumors in the dog were analyzed by computed tomography to establish criteria for identifying tumor types by computed tomography characteristics. Meningiomas could be distinguished from tumors within the brain parenchyma because they usually were broad-based, peripherally located masses that were enhanced homogeneously with contrast material. Among parenchymal tumors, astrocytomas were not distinguished easily from oligodendrogliomas because both tumors had similar features of ring-like and nonuniform enhancement, and poorly defined tumor margins. Choroid plexus tumors were seen as well-defined, hyperdense masses that had marked, uniform contrast enhancement. Pituitary tumors were distinguished readily by their location, minimal peritumoral edema, uniform contrast enhancement, and well-defined margins. Distinguishing features of other less frequently seen tumors (ependymoma, primitive neuroectodermal tumor, glioma, and neoplastic reticulosis) were not identified.

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Digestion of bentiromide and absorption of xylose in healthy cats and absorption of xylose in cats with infiltrative intestinal disease.

The digestion of bentiromide and the absorption of D-xylose was measured in 17 clinically healthy cats. The plasma xylose concentrations of the healthy cats were compared with values from 9 cats with diffuse infiltrative intestinal disease. The cats were administered 16.7 mg of bentiromide/kg and 0.5 g of xylose/kg via a stomach tube. Plasma samples were obtained before administration and 30, 60, 90, and 120 minutes after administration. The maximum mean plasma p-aminobenzoic acid concentration occurred at 60 minutes, with a value of 386 +/- 134 micrograms/dl (mean +/- SD). The maximum mean plasma xylose concentration also occurred at 60 minutes, with a value of 26.0 +/- 9.2 mg/dl. Plasma concentrations of p-aminobenzoic acid and xylose were lower in healthy cats than those reported for healthy dogs. There was no significant difference between xylose concentrations in healthy cats and cats with infiltrative intestinal disease.

4-Aminobenzoic Acid↗

Central nervous system lymphosarcoma in the dog.

Central nervous system lymphosarcoma was diagnosed in 8 dogs with seizures and clinical signs compatible with multifocal central nervous system involvement. Cerebrospinal fluid analysis showed high white cell counts with abnormal lymphoid cells in all dogs, and high protein concentration in 5 dogs. Two dogs were given systemic anticancer chemotherapy, and 4 dogs were given a combination of systemic chemotherapy, intrathecal cytosine arabinoside, and craniospinal irradiation, resulting in marked improvement of the clinical signs.

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Radioactive iodine therapy in cats with hyperthyroidism.

Eleven cats with hyperthyroidism were treated with radioactive iodine (131I). Previous unsuccessful treatments for hyperthyroidism included hemithyroidectomy (2 cats) and an antithyroid drug (7 cats). Two cats had no prior treatment. Thyroid scans, using technetium 99m, showed enlargement and increased radionuclide accumulation in 1 thyroid lobe in 5 cats and in both lobes in 6 cats. Serum thyroxine concentrations were high and ranged from 4.7 to 18 micrograms/dl. Radioactive iodine tracer studies were used to determine peak radioactive iodine uptake (RAIU) and effective and biological half-lives. Activity of 131I administered was calculated from peak RAIU, effective half-life, and estimated thyroid gland weight. Activity of 131I administered ranged from 1.0 to 5.9 mCi. The treatment goal was to deliver 20,000 rad to hyperactive thyroid tissue. However, retrospective calculations based on peak RAIU and effective half-life obtained during the treatment period showed that radiation doses actually ranged from 7,100 to 64,900 rad. Complete ablation of the hyperfunctioning thyroid tissue and a return to euthyroidism were seen in 7 cats. Partial responses were seen in 2 cats, and 2 cats became hypothyroid. It was concluded that 131I ablation of thyroid tumors was a reasonable alternative in the treatment of hyperthyroidism in cats. The optimal method of dosimetry remains to be determined.

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Radiotherapy of brain tumors in dogs.

Brain tumors in 4 dogs were treated with external beam, megavoltage radiation. X-ray computed tomography was used to localize and characterize brain tumors and to assess treatment response. Total radiation doses were 3,000 or 3,600 rad, given in 5 or 6 fractions over 14 to 19 days. Complete tumor regression, as determined from computed tomography scans, improvement in clinical signs, and reduction in medication, were documented in all irradiated dogs. The median survival time for irradiated dogs was 322 days, which was significantly (P less than 0.05) longer than the median survival time of 56 days in 8 dogs with brain tumors treated symptomatically. The one-year survival rate for the irradiated dogs, after correcting for deaths from intercurrent disease, was 100%. It was concluded that canine brain tumors may be treated effectively by use of megavoltage radiation.

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X-ray computed tomography of brain tumors in cats.

X-ray computed tomography (CT) was used to depict intracranial space-occupying lesions in 5 cats. Computed tomographic findings were confirmed by surgical biopsy in 2 cases and at necropsy in 3 cases. The detailed anatomic information provided by CT scans facilitated surgical removal of a brain tumor in 2 cats, and allowed accurate tumor localization and dose optimization for radiation therapy in 1 cat. It was concluded that CT provides information required for accurate diagnosis and treatment of feline brain tumors.

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Radiotherapy and hyperthermia in the treatment of fibrosarcomas in the dog.

Ten dogs with oral or external nasal fibrosarcoma were treated sequentially with orthovoltage radiation and radiofrequency (RF)-induced hyperthermia. Total radiation doses ranged from 3,200 to 4,800 rad given in 8 to 12 fractions of 400 rad. Immediately after 2 to 4 radiation treatments, hyperthermia was given. Six oral fibrosarcomas were heated to 50 C for 30 sec, using a hand-held RF generator. Four nasomaxillary fibrosarcomas were heated to 43 C for 30 minutes, using a 500-kHz RF generator. Hyperthermia of 50 C resulted in tumor necrosis and infection in 3 dogs and fatal septicemia in 1 dog. Nine of 10 tumors responded to therapy. One year after therapy, 5 dogs were free of disease. Tumor regrowth occurred in 5 dogs. Mean time to tumor regrowth and mean survival time of all dogs were 343 and 398 days, respectively. The results suggested that sequential radiation-hyperthermia is an effective therapeutic regimen for canine fibrosarcoma. It was concluded that this modality not only may be beneficial in the treatment of canine tumors but may be useful for designing new therapeutic approaches to similar tumors in man.

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Relative uptake of low- and high-osmolality contrast media in CT of brain tumors.

The magnitude and time course of contrast enhancement in spontaneous canine brain tumors was determined for two contrast agents: meglumine iothalamate and sodium meglumine ioxaglate. Tumor enhancement during contrast infusion and at 5, 10, 15, 30 and 45 minutes was measured using quantitative computed tomography. Blood iodine was measured using x-ray fluorescence. Peak contrast enhancement occurred during the infusion, and the magnitude was the same for both agents. Per gram of iodine infused, blood iodine was 12.4% higher with ioxaglate than iothalamate. The monoionic dimer ioxaglate is as effective as iothalamate for enhancement of canine brain tumors.

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Probable essential thrombocythemia in a dog.

Essential thrombocythemia (ET) in an 11-year-old dog was characterized by persistently high platelet counts (range, 4.19 X 10(6)/microliters to 4.95 X 10(6)/microliters, abnormal platelet morphology, marked megakaryocytic hyperplasia in the bone marrow, absence of circulating megakaryoblasts, and history of splenomegaly and gastrointestinal bleeding. Increased numbers of megakaryocytes and megakaryoblasts (15% to 20%) in the bone marrow were confirmed by a positive acetylcholinesterase reaction. Another significant finding was the presence of a basophilia in blood (4,836/microliters) and bone marrow. The marked persistent thrombocytosis, absence of reactive (secondary) thrombocytosis, abnormal platelet morphology, and quantitative and qualitative changes in the megakaryocytic series in the bone marrow suggested the presence of a myeloproliferative disease. Cytochemical and ultrastructural findings aided in the diagnosis of ET. The dog was treated with radiophosphorus. The results was a rapid decline in the numbers of megakaryoblasts and megakaryocytes in the bone marrow and platelets and basophils in the peripheral blood. The dog died unexpectedly of acute necrotizing pancreatitis and diabetes mellitus before a complete remission was achieved.

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Relative uptake of low- and high-osmolality contrast media in CT of brain tumors.

The magnitude and time course of contrast enhancement in spontaneous canine brain tumors was determined for two contrast agents: meglumine iothalamate and sodium meglumine ioxaglate. Tumor enhancement during contrast infusion and at 5, 10, 15, 30, and 45 min was measured using quantitative computed tomography. Blood iodine was measured using x-ray fluorescence. Peak contrast enhancement occurred during the infusion, and the magnitude was the same for both agents. Per gram of iodine infused, blood iodine was 12.4% higher with ioxaglate than iothalamate. The monoionic dimer ioxaglate is as effective as iothalamate for enhancement of canine brain tumors.

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