Biomedical subjects

K A Hahn

Publications and source records attributed to K A Hahn.

At least 37 records · Page 2Linked to original sources

PubMed1990

Comparison of survey radiography with ultrasonography and x-ray computed tomography for clinical staging of subcutaneous neoplasms in dogs.

A study of 26 dogs (examined consecutively) with infiltrative subcutaneous neoplasms (mastocytoma, n = 11; soft tissue sarcoma, n = 13; and adenocarcinoma, n = 2) was conducted. Dogs were evaluated by physical examination, survey radiography, ultrasonography (US), and x-ray computed tomography (CT) prior to surgical excision of the tumor. The purpose of the evaluation was to accurately define gross neoplastic margins before surgical excision and to determine whether a difference could be observed between routine clinical staging (physical examination and survey radiography) and more detailed clinical staging (US and CT imaging). The clinical stage of 5 of 26 neoplasms assessed by US and of 17 of 26 neoplasms assessed by CT was determined to be more advanced because of previously undetected neoplasia, greater neoplastic size, or greater tissue invasiveness. Preoperative imaging of infiltrative subcutaneous neoplasms, using US and CT, is highly recommended to accurately determine gross neoplastic margins.

Adenocarcinoma↗

PubMed1990

Single-phase methylene diphosphate bone scintigraphy in the diagnostic evaluation of dogs with osteosarcoma.

In this study, 25 dogs each with a histopathologically diagnosed appendicular or axial osteosarcoma were prospectively and consecutively examined by methylene diphosphate nuclear scintigraphy. Scannings that revealed scintigraphically enhanced focal increased activity via bone uptake of the 99mTc methylene diphosphate radionuclide at sites other than the primary tumor site were compared with scintigrams obtained from dogs without osteosarcoma. Secondary scintigraphic sites were evaluated by survey radiography and, if possible, by histologic examination (biopsy or necropsy specimens). On the basis of our findings, scintigraphy seems to be more efficient than physical examination and radiographic bone survey for the diagnosis of multicentric, metachronous, or metastatic canine osteosarcoma.

Animals↗

PubMed1989

Use of cisplatin for control of metastatic malignant mesenchymoma and hypertrophic osteopathy in a dog.

Cisplatin (cis-diammine-dichloroplatinum) treatment induced partial remission of pulmonary metastatic malignant mesenchymoma and nearly complete radiographic remission of hypertrophic osteopathy in a 14-year-old Beagle. Cisplatin was given once every 3 weeks. Clinical signs of hypertrophic osteopathy resolved one week after initiation of treatment. Partial remission of pulmonary metastases and partial radiographic remission of hypertrophic osteopathy was seen 6 weeks after initiation of treatment. Previous treatment of neoplasia-related hypertrophic osteopathy has consisted of removal of the initiating mass or vagotomy. In this case, appropriate chemotherapy was used to control clinical signs and progression of hypertrophic osteopathy.

Animals↗

PubMed1988

Functional considerations in partial foot amputations.

Recent developments in both surgical techniques and prosthetic management have improved the prognosis for foot amputations between the transmetatarsal and Syme's levels. Retention of active ankle motion is often permitted by partial foot amputations. Vocational and avocational requirements for active, voluntary ankle motions should be considered preoperatively in selected patients. Three case reports are used to illustrate this concept. Appropriate surgical techniques and prosthetic devices may improve the quality of life for some individuals requiring distal lower extremity amputations.

Amputation, Surgical↗

PubMedDate not supplied

Prognosis factors for survival in cats after removal of a primary lung tumor: 21 cases (1979-1994).

OBJECTIVE: To identify possible prognostic factors for survival time in cats with a primary lung tumor after surgical excision. STUDY DESIGN: Retrospective clinical study. ANIMAL POPULATION: 21 cats with histologically confirmed primary lung tumors removed surgically. METHODS: Medical records for cats treated between 1979 and 1994 at 14 participating veterinary referral hospitals were reviewed. RESULTS: After surgical resection and recovery, 18 cats died from metastatic disease with a median survival time of 115 days (range, 13 to 1,526 days). Three cats were lost to follow-up at 119 days, 251 days, and 410 days after the surgical procedure. Contingency table analysis to determine if an association existed between clinical findings (breed, age, gender, body weight, clinical signs, duration of clinical signs, and radiographic findings) or histological features and survival time was performed. Only histological morphology of the primary lung tumor showed a significant association with survival time. Twelve cats with moderately differentiated tumors had a significantly longer survival time (median, 698 days; range, 19 to 1,526 days) than the nine cats with poorly differentiated tumors (median, 75 days; range, 13 to 634 days). CONCLUSIONS: Surgical resection of a solitary primary lung tumor in cats is indicated. CLINICAL RELEVANCE: A poor prognosis for long-term survival is warranted for those cats having a poorly differentiated primary lung tumor.

Adenocarcinoma, Bronchiolo-Alveolar↗

PubMedDate not supplied

The use of colonic irrigation to control fecal incontinence in dogs with colostomies.

OBJECTIVE: To determine if once-daily colonic irrigation results in fecal continence for a 24-hour period in dogs with colostomies and if colonic volume increased in response to the irrigation. STUDY DESIGN: A prospective controlled experimental study. ANIMALS: Four intact male and one intact female mixed breed dogs. MATERIALS: All dogs received left end-on paralumbar colostomies. Four dogs received once-daily colonic irrigation for 8 weeks, whereas the control dog did not. Daily fecal weights were recorded for the length of the study in all dogs. Barium enema studies and volumetric studies were used to determine colonic volumes. RESULTS: Daily fecal weights were significantly decreased in treatment dogs compared with the control dog. Colonic volume increased in irrigated dogs in response to daily irrigation over the 8 week period of the study. CONCLUSIONS: Colonic irrigation resulted in significantly decreased fecal production over a 24-hour period. Therefore management of dogs with colostomies would be more practical and cost effective. It did not result in complete fecal continence in this study. Further clinical studies are indicated to determine if longer periods of irrigation would result in complete continence.

Animals↗

PubMedDate not supplied

Right leg muscle atrophy and osteopenia caused by renal adenocarcinoma in a cockatiel (Melopsittacus, undulatus).

A 7-year-old cockatiel presented with a 1 week history of right leg lameness. A renal adenocarcinoma invading and constricting the right ischiatic nerve resulted in disuse atrophy of the affected leg and radiographic evidence of osteopenia. This report illustrates the natural behavior, radiographic, and pathologic appearance of malignant renal tumors in birds.

Adenocarcinoma↗

PubMedDate not supplied

Is maintenance chemotherapy appropriate for the management of canine malignant lymphoma?

A retrospective study was conducted between two groups of dogs with histopathologically diagnosed multicentric malignant lymphoma to determine if treatment with either short-term or continuous chemotherapy resulted in a significant difference in first-remission length or survival time. One group was treated with single agent, short-term (three cycles) of doxorubicin. Dogs obtaining complete remission while receiving doxorubicin were given no further chemotherapy. The other group received combination agent, long-term chemotherapy consisting of cyclophosphamide, vincristine sulfate, and prednisone (COP). Dogs obtaining complete remission on COP by the end of 6 weeks were given maintenance chemotherapy of cyclophosphamide, prednisone and methotrexate. One hundred and five dogs were treated. Thirty-eight dogs received doxorubicin and 67 received COP. All dogs were evaluated at 6 weeks for response to chemotherapy and followed until death. No significant differences were observed in first-remission length or survival time when comparing dogs treated with either short-term doxorubicin or long-term COP (P greater than 0.05). Sex, weight, age, clinical stage, performance status, histopathologic cell type, and grade were not significant factors for determining the responsiveness to either chemotherapy protocol. However, within either treatment group, significant differences in first-remission length were observed in dogs evaluated histopathologically by the Keil and NCI working formulation and in survival time when evaluated by performance status (P less than 0.05).

Animals↗

PubMedDate not supplied

Dose response and time course of carboplatin-induced micronucleated polychromatic erythrocytes in the cat: implications for combination carboplatin chemotherapy.

The dose response and time course of micronucleated polychromatic erythrocytes (mPCE) in cat peripheral blood induced by various doses (150-250 mg/m2) of carboplatin in vivo was determined. The data indicate that carboplatin produced a significant (p < 0.05) dose-dependent increase in the number of mPCE over baseline values; however, the times following carboplatin administration when mPCE were first observed differed significantly (p < 0.05) between the three carboplatin dose groups. mPCE were present in significantly greater numbers (p < 0.05) on smears at an earlier time interval following a single carboplatin dose of 150 mg/m2 than for a dose of either 200 or 250 mg/m2. The peak number of mPCE occurred on days 7, 14 and 17.5 following administration of a carboplatin dose of 150, 200 and 250 mg/m2, respectively. The pattern of time course delay following carboplatin administration suggests that the block of erythropoietic stem cells in G2 is dose dependent. Indeed, the administration of carboplatin arrested the cell cycle in the G2 phase and, at higher doses, diminished the number of cycling erythroid precursor cells. mPCE were apparent in blood smears only after recovery from this arrest and resumption of replication. This observation has implications for the scheduling of carboplatin administration when used in combination with other anticancer drugs.

Animals↗

PubMedDate not supplied

Primary rib tumors in 54 dogs.

Fifty-four dogs with primary tumors of the rib were evaluated. Thirty-four dogs had osteosarcomas, 15 dogs had chondrosarcomas, three dogs had hemangiosarcomas, and two dogs had fibrosarcomas. Forty-nine dogs had en bloc excision. Within the osteosarcoma group, nine animals received postoperative adjuvant chemotherapy. These animals had significantly longer median disease-free intervals (225 days) and median survival times (240 days) than dogs with osteosarcoma treated by surgery alone (median disease-free interval, 60 days; median survival, 90 days). Chondrosarcoma had a better prognosis (median disease-free interval, 1,080 days; median survival, 1,080 days) than osteosarcoma, hemangiosarcoma, or fibrosarcoma of the rib. Age, weight, sex, number of ribs resected, tumor volume, and total cisplatin dose did not influence survival nor disease-free interval.

Animals↗

PubMedDate not supplied

Effect of infusion regime on doxorubicin pharmacokinetics in the cat.

In the pharmacokinetic evaluation of a single doxorubicin dose calculated by body surface area (25 mg/m2) or body weight (1 mg/kg body weight) and given intravenously as a 10-, 15-, or 20-minute infusion, the rate of doxorubicin infusion (mg per minute per m2 or mg per minute per kg) correlated positively with clearance and the distribution rate constant alpha, and it inversely correlated with area under the plasma concentration versus time curve (AUC). These findings suggest that a slower infusion rate results in a greater AUC and longer distribution phase than a faster infusion rate and indicates the importance of normalizing dosage regimes by infusion rate rather than by infusion duration when considering dose-response phenomena in veterinary patients.

Adenocarcinoma↗

PubMedDate not supplied

Ultrasonographic and cytopathological diagnosis of exocrine pancreatic carcinoma in the dog and cat.

This study describes the ultrasonographic and cytopathological characteristics of malignant neoplasms of the exocrine pancreas and their value in making an antemortem diagnosis. The medical records of eight dogs and five cats were reviewed. The clinical presentations were variable and at times mimicked pancreatitis. Overall, cytopathology of ultrasound or fluoroscopic-guided biopsies or fine-needle aspirates, or impressions from surgical biopsies were helpful in establishing the diagnosis in 10 of 12 animals where it was performed. Histopathology of ultrasound or fluoroscopic-guided biopsies provided a diagnosis in five of six cases where it was performed.

Animals↗

PubMedDate not supplied

Detection and clinical significance of plasma glutathione-S-transferases in dogs with lymphoma.

BACKGROUND: The objective of this study was to determine if glutathione-S-transferases were detectable in the plasma of dogs and to determine if concentrations of the a- and pi-subtypes were related with tumor response to single agent anthracycline (e.g., doxorubicin) chemotherapy in dogs with lymphoma. MATERIALS AND METHODS: Plasma was obtained from 10 healthy, normal dogs and from 11 dogs with lymphoma before treatment, 3 weeks after 1 dose of doxorubicin and every 3 weeks thereafter until relapse (the physical detection of recurrent and enlarged peripheral lymph nodes). Plasma concentration of alpha and pi-GST was determined by use of an ELISA technique with well plates pre-coated with IgG[anti-Canine alpha-GST or anti-Human pi-GST]. RESULTS: Mean plasma alpha-GST concentrations did not significantly decline after 1 dose of doxorubicin chemotherapy; however, mean plasma alpha-GST concentrations were markedly increased (p < 0.05) at the time of relapse (the physical detection of recurrent and enlarged peripheral lymph nodes). CONCLUSIONS: In this study we show that a relationship exists between the plasma alpha-GST concentration and the clinical response of dogs with lymphoma to doxorubicin chemotherapy.

Animals↗

PubMedDate not supplied

Direct action by doxycycline against canine osteosarcoma cell proliferation and collagenase (MMP-1) activity in vitro.

BACKGROUND: Matrix metalloproteinases (MMPs) produced by tumor cells disrupt the integrity of the extracellular matrix (ECM). Inhibiting MMPs activity could significantly reduce tumor invasion and metastasis. MATERIALS AND METHODS: Canine osteosarcoma (OSA) cells were exposed to doxycycline in vitro to determine whether this chemically modified tetracycline had antiproliferative and anticollagenolytic activity. RESULTS: Doxycycline significantly reduced cell proliferation in a dose dependent manner. Doxycycline at the doses of 5 and 10 micrograms/ml suppressed cell number 50% and 72%, respectively. Furthermore, doxycycline significantly reduced collagenase activity at the doses of 10 and 20 micrograms/ml by 35% and 50%, respectively. OSA cells did not produce any endogenous collagenase in the culture medium. CONCLUSIONS: This study has shown that doxycycline at doses greater than 5 micrograms/ml in vitro significantly decreases cell proliferation and collagenase (MMP-1) activity. Prospective studies should be conducted to determine if doxycycline, a chemically modified tetracycline with low systemic toxicity, has specific anti-collagenase activity in vivo. Our studies indicate that canine osteosarcoma represents a suitable model for additional in vitro and in vivo studies.

Animals↗

PubMedDate not supplied

Inhibitors of intracellular chloride regulation induce cisplatin resistance in canine osteosarcoma cells.

The objective of this study was to examine the role of ion transport mechanisms in clinical anticancer drug resistance. Reduction in intracellular accumulation of cisplatin is believed to be an early change in cisplatin-resistant cells, and may be dependent on the concentration of intracellular chloride (Cl-) ions and intracellular pH. The primary aim of this study was to describe the modifying effects of NHMA (5-N,N hexamethylene; amiloride), a Na+/H+ antiport inhibitor, and/or SITS (4-acetamido-4';isothiocyanostilbene-2,2'-disulfonic acid), a HCO3-/Cl- transport inhibitor, in bicarbonate-containing or bicarbonate-free media on cisplatin (cis-diamminedichloroplatinum(II); CDDP) toxicity between known cisplatin-sensitive (COS31) and cisplatin-resistant (COS31/rCDDP) canine osteosarcoma cells. This study has shown that cell survival can be influenced by the inhibition of the Na(+)-dependent HCO3-/Cl- exchanger using SITS. The addition of SITS increases the intracellular Cl- concentration in canine osteosarcoma cells cultured in a bicarbonate-containing media. In a bicarbonate-free media, the addition of SITS results in a decrease in the cytotoxic action of cisplatin.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗

PubMedDate not supplied

Feline breast carcinoma as a pathologic and therapeutic model for human breast cancer.

The United States pet population has been a vastly underutilized resource for cancer therapy studies. Naturally occurring tumors in pet animals develop twice as frequently as in man, have histopathologic features and a biologic behavior similar to tumors in man, and progress at a more rapid rate than in man. Cancer of the breast is the most common major cancer in women and the third most commonly reported cancer in cats. Breast cancer is probably the most feared cancer in women because of its frequency and its psychological impact. Breast cancer in the cat is highly malignant, rapidly metastasizing, and often a fatal disease. This report will discuss the comparative nature of breast cancer and the advantage of using the tumor-bearing cat as a pathologic and therapeutic model for the study of human breast cancer.

Animals↗

PubMedDate not supplied

Naturally occurring tumors in dogs as comparative models for cancer therapy research.

The United States pet population has been a vastly underutilized resource for cancer therapy studies. Naturally occurring tumors in dogs develop twice as frequently as in man, have histopathologic features and a biologic behavior similar to tumors in man, and progress at a more rapid rate than in man. Cancer is one of the leading causes of death in man and dogs. The canine malignancies that are of practical use for comparative therapeutic studies include lymphoma, mammary tumors, oral melanoma, lung tumors, nasal tumors, soft tissue sarcomas, and osteosarcoma. This report will discuss the comparative nature of these malignancies and the current trends in clinical cancer research, namely dose intensification and biomodulation, using naturally occurring tumors in client-owned dogs.

Animals↗

PubMedDate not supplied

Metastatic pheochromocytoma in a parakeet.

Pheochromocytoma, a tumor of the adrenal medulla, was diagnosed in a budgerigar based on gross, histopathologic, and electron microscopic findings.

Adrenal Gland Neoplasms↗