PubMed Health⌕ Search

Biomedical subjects

L C Stephens

Publications and source records attributed to L C Stephens.

At least 163 records · Page 9Linked to original sources
PubMed1983

Primary pulmonary fibrosarcoma associated with Spirocerca lupi infection in a dog with hypertrophic pulmonary osteoarthropathy.

A dog with severe subperiosteal cortical thickening in all 4 limbs was found at necropsy to have a small noncircumscribed firm lesion in a lung lobe. Microscopically, the lung lesion was a fibrosarcoma that contained several adult nematodes identified as Spirocerca lupi. Lesions were not found in the esophagus or aorta, which are the typical locations for lesions caused by this parasite. Fibrosarcomas have been associated with S lupi infection in the esophagus. In this case, the nematode localized and reached maturity in an aberrant location and apparently participated in the development of a fibrosarcoma at this site.

Animals↗
PubMed1983

Late effects of 50 MeV d leads to Be neutron and cobalt-60 irradiation of rhesus monkey cervical spinal cord.

The cervical spinal cords of 30 rhesus monkeys were irradiated with 50 MeV d leads to Be neutrons or 60Co gamma rays to evaluate the dose-response relationships for radiation myelopathy. Three groups were treated with 50 MeV d leads to Be neutrons using dosage schedules of 1300 rad n gamma (Group I), 1425 rad n gamma (Group II), or 1550 rad n gamma (Group III) in nine fractions over 29 days. Three groups were irradiated with 60Co gamma rays using dosage schedules of 4620 rad (Group IV), 5390 rad (Group V), or 5940 rad (Group VI) in 22 fractions over 29 days. A significant dose-response relationship was observed for the groups treated with neutrons. Whereas none of the monkeys in Group I showed clinical evidence of neurologic dysfunction, all five animals in Group III became paralyzed. One animal in Group II developed transient neck stiffness and mild unilateral leg paresis. No definitive signs of neurologic injury were seen in any of the animals irradiated with 60Co. The histopathologic changes correlated well with the clinical observations. All of the animals in Group III exhibited moderate to severe malacia and demyelination of the white matter of the cervical spinal cord. The histologic data indicated that the RBE for five times weekly fractionation (approximately 270 rad 60Co fractions) was in the range of 4.2 to 4.6, since the malacia and demyelination in the spinal cords irradiated with 5940 rad of 60Co gamma-rays were greater than that observed in the spinal cords irradiated with 1300 rad n gamma of neutrons but less than the changes in those irradiated with 1425 rad n gamma of neutrons.

Animals↗
PubMed1983

Resistance of Rowett athymic (nude) rats to casein-induced amyloidosis.

Rowett athymic (nude) rats (n = 18) were injected subcutaneously (36 to 86 injections) or intraperitoneally (10 to 56 injections) with 10% casein solution to attempt to induce amyloidosis. Neither the injected nor the control rats had gross or microscopic evidence of amyloid deposition. Serum beta- and gamma-globulin concentrations were significantly higher in the injected rats than in the control rats. There were no significant changes in blood urea nitrogen or serum alanine aminotransferase values of the experimental groups compared to the control groups. The relationship of amyloidosis to deficient cell-mediated immunity and the use of the nude rat for the study of the pathogenesis of amyloidosis are discussed.

Amyloidosis↗
PubMed1982

50-MEVd leads to Be neutrons: a comparison of normal tissue tolerance in animals with clinical observations in patients.

The acute and late effects of 50 MeV neutrons were investigated by irradiating a variety of organ systems in large animals using dosage schedules similar to those that have been employed clinically. The RBEs for acute effects in pig skin and rhesus monkey oral mucosa were significantly less than the RBEs for late effects. This observation has also been noticed clinically. The RBEs for late effects in pig skin, rhesus monkey oral mucosa, and rhesus monkey kidney were consistent with values of 3.1 to 3.4 relative to approximately 200 rad 60Co fractions and approximately 2.2 to 2.6 relative to approximately 400 rad 60Co fractions. The RBE for radiation myelitis was significantly greater (4.2 to 4.6 relative to approximately 270 rad 60Co fractions). The tolerance doses for 50 MeVd leads to Be neutrons in large animals were approximately 2200 radn gamma/61/2 weeks for skin contraction, approximately 2100 radn gamma/61/2 weeks for oromucosal necrosis, approximately 1300 radn gamma/41/2 weeks for radiation myelitis, and approximately 960 radn gamma/4 weeks for radiation nephritis. These values correlate well with clinical observations at TAMVEC, since the majority of soft tissue complications in patients occurred following tissue doses in excess of 2100 radn gamma.

Animals↗
PubMed1982

Growth characteristics of human colonic adenocarcinomas propagated in the Rowett athymic rat.

Two human colonic adenocarcinoma cell lines were propagated in the Rowett athymic rat. Line LoVo displayed a well-differentiated morphology and exhibited progressive growth over a 70-day observation period with a doubling time of 8.5 days throughout. No metastatic involvement was noted. Xenografts of SW 620 cells were undifferentiated and highly necrotic. These tumors grew progressively for approximately 30 days with a doubling time of 5.5 days, but over 90% of the animals exhibited a spontaneous regression with a mean time to total regression of 51 +/- 3 (S.E.) days. Animals which had rejected the SW 620 xenografts would not support the growth of either the SW 620 or LoVo xenografts when challenged a second time with inocula producing a 100% tumor incidence in control rats. No metastatic involvement was noted for the SW 620 xenografts, but the tumors frequently invaded the underlying musculature and protruded into the peritoneal cavity without producing ascites or tumor nodules at sites distant from the primary.

Adenocarcinoma↗
PubMed1981

Relationship of hypothyroidism to diabetes mellitus, renal amyloidosis, and thrombosis in purebred beagles.

Review of 484 records for colony Beagles revealed an association between hypothyroidism and diabetes mellitus. The average time between first notation of hypothyroidism and later development of diabetes mellitus was 2.8 years. An association was also made with hypothyroidism, renal amyloidosis, and thrombosis. Hypothyroidism was significantly related to thrombosis, thrombosis was significantly related to renal amyloidosis, but hypothyroidism and renal amyloidosis were not significantly related. Of 62 hypothyroid dogs, 11 were diabetic and 7 others had thrombosis. Six hypothyroid dogs had renal amyloidosis, 4 of which had thrombosis. One dog had renal amyloidosis and thrombosis in the absence of hypothyroidism. There does not appear to be an association with any of the lesions and previous low-dose, whole-body gamma, or sham irradiation.

Amyloidosis↗
PubMed1980

Infiltrative lipoma in dogs.

Infiltrative lipomas, similar to those described in man, were diagnosed in 12 dogs of various breeds, sexes, and ages. The neoplasms were poorly delineated, soft enlargements in muscle and connective tissue that caused dysfunction because of mechanical interference or pressure pain. The neoplasms consisted of differentiated fat cells that had infiltrated between or replaced muscle, collagen fibers or both. Single or multiple recurrences followed surgical removal in four of eight dogs: no follow-up was possible in the other four.

Animals↗
PubMed1975

Introducing a stroke service in a general hospital setting.

A stroke service was begun at a private general hospital in Florida that consisted of a weekly spouse group meeting, and included treatment services already in existence, that is, occupational therapy, physical therapy, speech therapy, and social work. The five major objectives of this program were early identification of stroke patients who had rehabilitation potential, support for families of stroke patients, coordinated discharge planning as well as better communication among the professional services, and increased discharge of patients to the home setting. This project demonstrates a means of introducing change in a general hospital setting.

Aged↗
PubMedDate not supplied

Antitumor and antimetastatic activity of the differentiating agent N-methylformamide in murine tumor systems.

N-Methylformamide (NMF), a cell-differentiating agent, was assessed for its antitumor activity against a fibrosarcoma (FSA), a hepatocarcinoma (HCA-I) and a mammary carcinoma (MCA-K), syngeneic to C3Hf/Kam mice. Tumors were grown as solitary tumors in the leg or as artificial or spontaneous micrometastases in the lung. NMF, at a dose of 300 mg/kg, was administered i.p. daily for 6 to 18 days. NMF slowed the growth of FSA and HCA-I tumors and totally inhibited the growth of the MCA-K tumor. However, the effect was transient; tumors resumed their pretreatment growth rate upon cessation of the treatment. Histologically, MCA-K tumors treated with NMF (300 mg/kg daily for six days) underwent considerable cell depopulation and reduction in mitotic activity. The number of artificial metastases, as well as the incidence and the number of spontaneous metastases, were markedly reduced by NMF. This resulted in a prolongation of the survival of mice that had artificial metastases of MCA-K tumor. The in vitro clonogenicity of MCA-K, but not of FSA or HCA-I cells, was reduced. However, in vivo reduction of MCA-K cell clonogenicity was minimal, if any. Thus, NMF is effective in restricting the growth of both solitary tumors and metastases, but the degree of response is highly dependent on tumor type.

Animals↗
PubMedDate not supplied

Experimental evaluation of ethanol-ethiodol for transcatheter renal embolization.

Adult mongrel dogs were used to evaluate and compare the use of ethanol and ethanol-Ethiodol for transcatheter renal arterial embolization. Each agent was administered into a main renal artery in five dogs and evaluated with regard to ease of use, radiopacity, arterial occlusion, parenchymal damage, and toxicity. Both agents were easy to inject, and no complications were encountered in any of the animals. Ethiodol added the ability to fluoroscopically monitor the infusate for reflux and distribution, yielded a more homogeneous distribution of the ethanol within the renal vasculature, and increased the embolic effects of the ethanol. Adding Ethiodol to ethanol should decrease the latter's complications since administration can be monitored fluoroscopically and a smaller volume of ethanol could perhaps be used to achieve the desired result. Additional research is needed to determine the safety of administering larger volumes of Ethiodol into the renal artery.

Animals↗
PubMedDate not supplied

An animal model of occlusion-hyperthermia of the liver.

An animal model of partial hepatic artery occlusion and radiofrequency (RF)-induced hepatic hyperthermia was developed in the New Zealand white rabbit. Seventy-seven percent (10/13) of animals survived partial hepatic artery occlusion, 82% (41/50) survived RF-induced hepatic hyperthermia, and 66% (24/36) survived combined occlusion-hyperthermia. Mesenteric infarction secondary to inadvertent embolization of intestinal arteries was the principal cause of death in animals undergoing partial hepatic artery occlusion. Extrahepatic thermal toxicity appeared to be the major cause of death in animals subjected to hepatic hyperthermia or occlusion hyperthermia although some animals showed evidence of hepatic necrosis as well. Recent developments in our laboratory hold the promise that extrahepatic thermal toxicity can be eliminated by selectively focusing heat into the liver allowing exploration of the efficacy of occlusion-hyperthermia in controlling VX-2 tumors implanted in the rabbit liver.

Animals↗
PubMedDate not supplied

Factors that influence diabetes patient teaching performed by hospital staff nurses.

Hospital staff nurses are frequently expected to teach patients and families with diabetes. A study was conducted to answer the questions: (1) According to nurses' perceptions, what factors influence conducting diabetes education? (2) Do staff nurses have sufficient knowledge to teach diabetes management principles? Thirty-nine staff nurses from adult units of a university hospital completed an investigator-designed survey and a Diabetes Knowledge Test (DKT). Eleven nurses attending a workshop on diabetes patient management were pre- and posttested to determine the workshop's effect on perceptions and knowledge. Perceived factors that interfered with teaching included lack of time, inadequate teaching skills, lack of patient interest in learning, and absence of a physician's order for teaching. The workshop had little influence on perceptions but significantly increased the mean DKT score from 70% to 78% (P = .03). The findings suggest that expecting all staff nurses to adequately educate patients in diabetes management may not be realistic.

Diabetes Mellitus↗
PubMedDate not supplied

Are clinical signs accurate indicators of the cause of central venous catheter occlusion?

BACKGROUND: Two hundred dysfunctional central venous catheters used for total parenteral nutrition and administration of cancer chemotherapy were radiographically examined in order to objectively identify thrombotic occlusions as the cause of catheter dysfunction. METHODS: Outcomes of radiographic dye injections were compared with factors such as the inability to aspirate blood or to infuse fluids, catheter type, and duration of catheter placement. RESULTS: Catheter type and duration of placement were not significant factors for predicting the type of dysfunction. Failure to withdraw blood was associated with 96% of the thrombosed catheters; this was also associated with 65% of the catheters with nonthrombotic dysfunctions. Once the cause of catheter occlusion was correctly identified, 90% of the catheters were restored to normal function. CONCLUSIONS: Inability to withdraw blood from a catheter does not necessarily mean it is occluded by thrombus. Mechanical complications account for a significant portion of dysfunctional catheters.

Catheterization, Central Venous↗
PubMedDate not supplied

Effect of whole-body hyperthermia on pharmacokinetics and tissue distribution of doxorubicin.

The effect of whole-body hyperthermia (41.5 degrees C, 2 h) on doxorubicin (DOX) tissue distribution and plasma pharmacokinetics was examined in rats bearing a subcutaneous fibrosarcoma. Tumour response to the hyperthermia regimen alone was minimal, but the combination of heat with DOX (5.0 mg/kg, i.v.) enhanced tumour growth delay. The combined therapy, however, showed increased toxicity to normal tissue (especially renal and cardiac). Although DOX levels in spleen tissue were higher in rats exposed to hyperthermia than in control normothermic rats, both groups had comparable levels of drug in tumour, heart, kidney, and small intestine tissue at all time-points examined. Compared with normothermic animals, hyperthermia-treated rats showed decreased DOX in the mean area under the concentration-time curve (AUC) and decreased plasma DOX t1/2 but increased plasma drug clearance. These heat-mediated alterations in DOX pharmacokinetic parameters, however, do not account for the significant increases in thermochemotherapy-mediated cytotoxicities observed in tumour, and in normal renal and cardiac tissues.

Animals↗