Biomedical subjects

J E Obradovich

Publications and source records attributed to J E Obradovich.

13 recordsLinked to original sources

PubMed2001

Granular cell tumor of the canine central nervous system: two cases.

Although pure granular cell tumors have been reported in various sites in the dog, only one tumor has been reported in the central nervous system. Two dogs presented with neurologic signs had brain lesions detected by magnetic resonance imaging in the area of the olfactory bulbs and frontal cortex. In both dogs, a clinical diagnosis of a granular cell tumor was made from tissues obtained from stereotactic biopsies guided by computed tomography. Surgical removal of the tumors was followed by histopathologic, ultrastructural, and immunocytochemical characterization. Although not conclusive, these studies indicated that the granular cells were not of leucocyte origin but may have been derived from the meninges. One dog died 12 months after surgery, and the other was alive 4 months later.

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PubMed1998

Imaging proliferation in vivo with [F-18]FLT and positron emission tomography.

Positron emission tomography (PET) is now regularly used in the diagnosis and staging of cancer. These uses and its ability to monitor treatment response would be aided by the development of imaging agents that can be used to measure tissue and tumor proliferation. We have developed and tested [F-18]FLT (3'-deoxy-3'-fluorothymidine); it is resistant to degradation, is retained in proliferating tissues by the action of thymidine kinase 1 (TK), and produces high-contrast images of normal marrow and tumors in canine and human subjects.

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PubMed1998

Efficacy of pyridoxine to ameliorate the cutaneous toxicity associated with doxorubicin containing pegylated (Stealth) liposomes: a randomized, double-blind clinical trial using a canine model.

A cutaneous reaction termed palmar-plantar erythrodysesthesia (PPES) or hand-foot syndrome can be dose limiting for Doxil, a doxorubicin containing pegylated (Stealth) liposome. The objective of this study was to determine the ability of concomitant pyridoxine therapy to prevent the development of PPES during Doxil therapy. Forty-one dogs with non-Hodgkin's lymphoma were randomized in a double-blind fashion to receive either oral pyridoxine or placebo daily during Doxil chemotherapy (1.0 mg/kg, i.v., every 3 weeks for a total of five treatments). Cutaneous toxicity was determined by clinical and histological scoring. No difference was observed in remission rates (71.4 versus 75%) achieved between groups. The likelihood of developing serious PPES and having to decrease or discontinue Doxil therapy was 4.2 times (relative risk) greater in placebo group dogs than in pyridoxine group dogs (P = 0.032). Pyridoxine did not completely abrogate PPES; however, it occurred later and less dramatically than in placebo-treated dogs and resulted in fewer treatment delays or discontinuations, allowing a higher cumulative dose of Doxil to be received. Compared to the 5.0 mg/kg cumulative target dose, pyridoxine-treated dogs received a median cumulative dose of 4.7 mg/kg (mean, 4.1 mg/kg), and the placebo-treated dogs received a median of 2.75 mg/kg (mean, 2.9 mg/kg; P < 0.028). A trend (P = 0.084) toward prolongation of remission length was observed in dogs receiving pyridoxine, which was likely attributable to their ability to receive more Doxil without delay or discontinuation. We conclude that pyridoxine is effective in delaying the onset and severity of PPES in this canine model.

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PubMed1996

Assessment of potential doubling time (Tpot), argyrophilic nucleolar organizer regions (AgNOR), and proliferating cell nuclear antigen (PCNA) as predictors of therapy response in canine non-Hodgkin's lymphoma.

The predictive potential of several proliferation indices for therapeutic outcome was investigated in 55 dogs with spontaneously occurring non-Hodgkin's lymphoma (NHL). Indices included potential doubling time (Tpot), argyrophilic nucleolar organizer region (AgNOR) frequency, and proliferating cell nuclear antigen labeling index (PCNA-LI). All tumors were of intermediate- or high-grade histology as assessed by the Working Formulation, and all dogs presented with disease of advanced clinical stage. All tumors were treated with an identical chemotherapeutic protocol. Tpot determination by a bromodeoxyuridine (BrdU) delayed-biopsy technique was readily applied in the dog. AgNOR frequency and PCNA-LI were easily obtained from archival, formalin-fixed, paraffin-embedded canine tissues. When accounting for all other prognostic variables by employing multivariate analysis, Tpot (p=0.017), and AgNOR frequency (p=0.021), but not PCNA-LI, were predictive of first remission duration. AgNOR frequency (p=0.033) was also predictive of survival time, and the predictive potential of Tpot approached significance (p=0.076). We conclude that Tpot and AgNOR frequency can be used as predictors of outcome in dogs with NHL, and spontaneous NHL in the dog may have significant potential as a model for further characterization of the association between tumor cell kinetics and chemoresponsiveness.

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PubMed1995

Liposome-encapsulated muramyl tripeptide phosphatidylethanolamine adjuvant immunotherapy for splenic hemangiosarcoma in the dog: a randomized multi-institutional clinical trial.

Canine splenic hemangiosarcoma (HSA) is a spontaneous tumor with high metastatic potential. Despite surgical excision, most dogs die within 2 months of diagnosis as a result of widespread visceral metastasis. This study was designed to determine the efficacy of liposome-encapsulated muramyl tripeptide phosphatidylethanolamine (L-MTP-PE) when used in combination with splenectomy and systemic chemotherapy for the treatment of HSA in the dog. Thirty-two dogs with HSA and without gross evidence of metastases were treated with splenectomy, stratified by clinical stage, and randomized to receive doxorubicin/cyclophosphamide chemotherapy and either L-MTP-PE immunotherapy or lipid equivalent (placebo liposomes). Dogs were subsequently followed to determine disease-free survival and overall survival times. The effects of L-MTP-PE on serum tumor necrosis factor-alpha and interleukin 6 activity were assessed on a small subset of dogs. Dogs receiving L-MTP-PE had significantly prolonged disease-free survival (P = 0.037) and overall survival (P = 0.029) compared with dogs receiving placebo. Dogs with clinical stage I disease had significantly prolonged disease-free survival (P = 0. 026) and overall survival (P = 0.017) compared with dogs with clinical stage II disease. Dogs receiving L-MTP-PE had significantly greater serum tumor necrosis factor-alpha (P < 0.001) and interleukin 6 (P = 0.007) activities compared with placebo-treated dogs. L-MTP-PE has significant antimetastatic activity in highly malignant, spontaneously occurring, splenic HSA in the dog. Canine HSA may have potential as a large animal model for additional investigation of antimetastatic chemoimmunotherapy.

Acetylmuramyl-Alanyl-Isoglutamine↗

PubMed1993

Toxicoses and efficacy associated with administration of mitoxantrone to cats with malignant tumors.

Eighty-seven cats with histologically confirmed malignant tumors were used in a prospective study to determine the toxicity of mitoxantrone, a dihydroxyquinone derivative of anthracene, which was administered at 21-day intervals at dosages ranging from 2.5 to 6.5 mg/m2 of body surface, IV. Eleven of these cats were treated concurrently with radiation but were evaluated separately. Each cat was evaluated for signs of toxicosis for 3 weeks after each dose was administered or until the cat developed progressive disease, or until the cat's quality of life diminished to an unacceptable level as determined by the owner or attending veterinarian. Although the primary purpose of this study was to determine a clinically useful dosage and to characterize the toxicoses associated with mitoxantrone administration, each cat was monitored for response to treatment. Forty-nine cats had been refractory to 1 or more treatment modalities prior to inclusion in this study. The most common signs of toxicosis after treatment with mitoxantrone were vomiting, anorexia, diarrhea, lethargy, sepsis secondary to myelosuppression, and seizures. Two cats died of complications that may have been attributed to mitoxantrone: 1 of cardiomyopathy and the other of pulmonary edema of an undetermined cause. Older cats were more likely to develop signs of toxicosis after the third or fourth mitoxantrone treatment than younger cats (P < or = 0.05). Cats with signs of toxicosis during the 21-day interval after administration of the first dose of mitoxantrone were significantly (P < or = 0.05) more likely to develop signs of toxicosis during the 21-day interval between the second and third doses of mitoxantrone.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Toxicoses associated with administration of mitoxantrone to dogs with malignant tumors.

One hundred twenty-nine dogs with histologically confirmed malignant tumors were used in a prospective study to determine the toxicity of the new dihydroxyquinone derivative of anthracene, mitoxantrone, which was administered IV at 21-day intervals at dosages ranging from 2.5 to 5 mg/m2 body surface area. Each dog was evaluated for signs of toxicosis for 3 weeks after each dose was administered or until the dog died, whichever came first. The number of dogs in each evaluation period were as follows: 1 dose (n = 129), 2 doses (n = 82), 3 doses (n = 43), 4 doses (n = 26), 5 doses (n = 19), 6 doses (n = 9), 7 doses (n = 6), 8 doses (n = 5), 9 doses (n = 3), and 10 doses (n = 1). The most common signs of toxicosis were vomiting, diarrhea, anorexia, and sepsis secondary to myelosuppression. None of the dogs died of complications resulting from mitoxantrone treatment. Dogs with signs of toxicosis during the 21-day interval from administration of the first dose of mitoxantrone were 95 times (P = 0.003) more likely to develop signs of toxicosis during the 21-day interval from the second dose of mitoxantrone. Similarly, dogs that developed signs of toxicosis during the 21-day interval from the administration of the second dose were 34 times (P less than 0.001) more likely to develop signs of toxicosis during the 21-day interval from the administration of the third dose. With each 1 mg/m2 increase in mitoxantrone, the odds of developing signs of toxicosis increased by 5.9 fold (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Efficacy of mitoxantrone against various neoplasms in dogs.

One hundred twenty-six dogs with histologically confirmed, measurable malignant tumors were evaluated in a prospective study to determine the response to the antineoplastic drug mitoxantrone. Ninety-five dogs had been refractory to one or more treatment modalities (surgery, n = 57; chemotherapy other than mitoxantrone, n = 37; radiation, n = 4; whole body hyperthermia, n = 1). The extent of neoplastic disease was determined immediately before each dose of mitoxantrone was administered (1 to 10 doses, 2.5 to 5 mg/m2 of body surface area, IV) 21 days apart. Each dog was treated with mitoxantrone until the dog developed progressive disease or until the dog's quality of life diminished to an unacceptable level as determined by the owner or attending veterinarian. A partial or complete remission (greater than 50% volume reduction) was obtained in 23% (29/126) of all dogs treated. Tumors in which there was a partial or complete remission included lymphoma (11/32), squamous cell carcinoma (4/9), fibrosarcoma (2/9), thyroid carcinoma (1/10), transitional cell carcinoma (1/6), mammary adenocarcinoma (1/6), hepatocellular carcinoma (1/4), renal adenocarcinoma (1/1), rectal carcinoma (1/1), chondrosarcoma (1/2), oral malignant melanoma (1/12), cutaneous malignant melanoma (1/1), myxosarcoma (1/1), mesothelioma (1/1), and hemangiopericytoma (1/1). Our results indicated that mitoxantrone induces measurable regression in various malignant tumors in dogs.

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PubMed1987

Serum immunoreactive gastrin activity in horses: basal and postprandial values.

Using commercially available diagnostic reagents, serum immunoreactive gastrin activity was measured in five normal horses that were starved of food and water for 24 hours. Blood samples were taken every 15 minutes for two hours. The horses were then fed a pelleted diet for 15 minutes and samples were taken every 15 minutes for a further two hours. Three further samples were taken at hourly intervals. The total sampling period was seven hours. Basal immunoreactive gastrin activity was lower than that reported in other mammals, ranging from a mean of 7.0 pg/ml to 13.8 pg/ml. At 30, 60 and 75 minutes after feeding, mean gastrin immunoreactivity was significantly elevated at 17.4, 19.8 and 18.2 pg/ml respectively. A late significant elevation occurred also five hours after feeding reading 19.4 pg/ml. This low activity may reflect a lower concentration of serum gastrin in the horse than in other mammals, or the methods used in the study may have failed to detect equine serum gastrins.

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PubMedDate not supplied

Evaluation of recombinant canine granulocyte colony-stimulating factor as an inducer of granulopoiesis. A pilot study.

Five healthy young adult dogs were given recombinant canine granulocyte colony-stimulating factor (rcG-CSF) at a dosage of 5 micrograms/kg/day subcutaneously for 4 weeks to evaluate the effect on complete blood cell counts. The mean neutrophil counts +/- standard deviation (SD) increased significantly (P less than 0.01) from 6,537/microliters +/- 1,726 (range, 4,950-9,512/microliters) to 26,330/microliters +/- 7,066 (range, 15,368-35,785/microliters) within 24 hours after the first injection of rcG-CSF. Mean monocyte counts +/- SD were significantly increased (P less than 0.05) from baseline values of 751/microliters +/- 168 (range, 444-891/microliters) to 2,514/microliters +/- 878 (range, 1,740-3,752/microliters) on day 5 of rcG-CSF administration. Mean neutrophil and monocyte counts (+/- SD) continued to increase reaching a maximum of 72,125/microliters +/- 15,073 (range, 50,915-96,278/microliters) and 3,972/microliters +/- 2,621 (range, 685-8,030/microliters), respectively by day 19. These increased neutrophil and monocyte counts were maintained until the administration of rcG-CSF was stopped. Blood counts returned to normal within 5 days after discontinuing the rcG-CSF. One week after discontinuing treatment, rcG-CSF was started again at 5 micrograms/kg/day subcutaneously. Within 48 hours following administration of rcG-CSF, mean neutrophil counts +/- SD increased from 5,860/microliters +/- 1,819 (range, 3,720-8,650/microliters) to 57,444/microliters +/- 8,173 (range, 43,983-68,278/microliters). Myeloid:erythroid ratios increased from a mean of 1.63:1 on day 1 prior to administration of rcG-CSF to 3.3:1 on day 10 in three dogs for which bone marrow samples were evaluated. Recombinant canine G-CSF did not cause clinically significant toxicosis in any of the dogs.

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PubMedDate not supplied

Use of recombinant canine granulocyte colony-stimulating factor to decrease myelosuppression associated with the administration of mitoxantrone in the dog.

Ten dogs were given mitoxantrone at a dose of 5 mg/m2 body surface area intravenously. Recombinant canine granulocyte colony-stimulating factor (rcG-CSF) was administered subcutaneously daily for 20 days after an infusion of mitoxantrone in five of these dogs to determine the effect of the hematopoietic growth factor on the duration and severity of myelosuppression. The median neutrophil counts dropped below normal (less than 3,000/uL) for 2 days in the dogs that received rcG-CSF, and for 5 days in the dogs that received only mitoxantrone. Four of five dogs not treated with rcG-CSF and none of those receiving rcG-CSF developed serious neutropenia (less than 1,500/uL). The neutrophil counts were significantly (P less than 0.05) higher in the rcG-CSF treated dogs at all time points except before the administration of the colony-stimulating factor, and the sixth day after the mitoxantrone was administered. These findings demonstrate that rcG-CSF is capable of reducing the duration and severity of mitoxantrone-induced myelosuppression.

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PubMedDate not supplied

Carotid body tumors in the dog. Eleven cases (1978-1988).

Case records of 11 dogs with histologically confirmed carotid body tumors were reviewed. Surgical excision had been attempted in ten dogs with carotid body tumors, and one dog had been euthanatized at diagnosis. There were no intraoperative deaths but perioperative mortality was 40%. Horner's syndrome and laryngeal paralysis were the most common postoperative morbidities. The median survival time after surgery alone in the four dogs that survived the perioperative period was 25.5 months (range, 12-45 months). Two dogs treated with postoperative radiation therapy had survival times of 6 and 27 months. Of the six dogs surviving the perioperative period, two dogs are still alive at 19 and 32 months postoperatively. Of the four dogs that died, one was euthanatized 12 months postoperatively for nontumor-related causes. The remaining three dogs died of distant metastases. The carotid body tumors studied were characterized by local tissue invasion, neurovascular complications after therapy, and a propensity to metastasize to multiple sites in the body.

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PubMedDate not supplied

Effect of recombinant canine granulocyte colony-stimulating factor on peripheral blood neutrophil counts in normal cats.

Recombinant canine granulocyte colony-stimulating factor (rcG-CSF) was administered subcutaneously at a dosage of 5 micrograms/kg/day to five healthy, young adult cats for 42 days. Mean neutrophil counts +/- standard deviation increased significantly (P < 0.001) from 10,966/microL +/- 2324 to 30,688/microL +/- 5296 within 24 hours after administration of the first dosage of rcG-CSF. Mean neutrophil counts reached 52,978/microL +/- 11,207 on day 6, representing a second significant increase (P < 0.01) over the previous 5 days. Mean neutrophil counts continued to increase, reaching 66,994/microL +/- 12,419 on day 14, then remaining within a range of 66,994 to 87,839/microL throughout the remainder of the study. The maximum mean neutrophil count was 87,839/microL +/- 8,695 on day 42. Neutrophil counts remained high until the administration of recombinant canine granulocyte colony-stimulating factor was discontinued 42 days after initiation of therapy. Once the rcG-CSF administration was discontinued, neutrophil counts returned to pretreatment values within 5 days. There were no significant changes in numbers of any of the other cell lines. There was no clinically significant toxicosis associated with the administration of rcG-CSF.

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