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Biomedical subjects

J McCall

Publications and source records attributed to J McCall.

At least 19 recordsLinked to original sources
PubMed1997

Comparison of thoracic radiographs with images transmitted via advanced telecommunications equipment.

OBJECTIVE: To compare thoracic radiographs of clinically normal dogs and dogs with mild clinical heartworm disease with images transmitted by a desk-top, two-way audiovisual teleconferencing system. DESIGN: Prospective, matched-set study. STUDY POPULATION: 50 thoracic radiographs from clinically normal and heartworm-infected dogs and the digitally transmitted images of those radiographs. PROCEDURE: Thoracic radiographs from 25 clinically normal dogs and 25 dogs infected with 1 to 24 heartworms were evaluated by 3 clinicians. Using classic criteria for heartworm disease, evaluations of radiographs and images transmitted digitally over 2 high-speed data-transfer telephone lines (56 kilobits/s/line) were performed. Clinicians were asked to determine whether dogs had radiographic signs of heartworm disease. RESULTS: Clinicians' ability to detect heartworm disease did not differ between interpretations of radiographs and those of transmitted images. CLINICAL IMPLICATIONS: Radiographic images transmitted via a teleconference system can be used to provide reliable diagnostic information. Thoracic radiographs can be interpreted at a remote site permitting rapid consultation and immediate advice on clinical management.

Animals↗
PubMed1997

Exploring novel chemotherapy treatments using the WWW.

A JAVA application, The Oncologists Workbench, which allows oncologists to estimate the influence of new cancer treatment schedules is being developed. The requirement for a rational approach to the design of chemotherapeutic regimens is well established [1]. Our prototype allows oncologists using the World Wide Web (WWW) to graphically construct treatment regimens while considering various toxic side effects. A simulation engine makes predictions of tumour growth based on previous clinical knowledge of response to treatment. The oncologist can then examine the predicted tumour response information with a specially constructed interactive viewer. These interlinked tools allow oncologists to develop and predict the effectiveness of novel chemotherapeutic regimens. This work is part of an ongoing collaboration between oncologists, mathematicians and computer scientists to provide tools for improving cancer chemotherapy.

Antineoplastic Agents↗
PubMed1997

Reduced transdermal absorption of N,N-diethyl-m-toluamide from a new topical insect repellent formulation.

Extensive absorption of the topical insect repellent N, N-diethyl-m-toluamide (DEET) causes systemic and local toxicities. This report describes the preparation and characterization of a new insect repellent formulation (FA), a PEG-polyacrylic acid polymer system, for its DEET release, in vitro skin permeation, and in vivo transdermal absorption properties; and for its relative repellency against Aedes aegypti mosquitoes. DEET release and skin permeation were studied in Franz diffusion cells. DEET transdermal absorption and relative repellency of FA were assessed in beagle dogs. A commercial DEET lotion (FB) and technical DEET (FC) were used as references. FA exhibited 19.5% and 61.7% decrease in DEET steady-state skin flux compared with FB and FC, respectively. At 15 mg DEET/kg, the absolute DEET transdermal bioavailability and Cmax were 13.4% and 154.3 ng/ml, respectively, for FA; and were 17.5% and 196.5 ng/ml, respectively, for FB. DEET half-lives (t1/2) for FA (2.52 hr) and FB (2.73 hr) were similar, while MRT for FA (4.99 hr) was significantly greater (p < 0.05) than that for FB (4.38 hr). FA showed lower mosquito biting rates at 1, 2, 3, 4, 5, and 6 hr postdose at 0.5 mg DEET/cm2. FA exhibited reduced in vitro skin permeation and in vivo transdermal absorption of DEET as well as superior repellency compared with FB. The PEG-polyacrylic acid polymer system is of value in the formulation of DEET lotions.

Administration, Topical↗
PubMed1992

Thrombolysis in high risk patients.

The advent of intra-arterially administered thrombolytic agents of minimal antigenicity, together with small gauge good torque control catheters, enables thrombolysis to be used in patients that may previously have been deemed unsuitable for thrombolytic therapy. Thrombolysis may be used even in the presence of factors formerly and empirically considered to be contra-indications. The continued use of thrombolytic agent may also be warranted despite iatrogenic complications such as vessel wall perforation, particularly if the alternative is major amputation. We report on a series of eight patients in whom intra-arterial tissue plasminogen activator was used despite either recent vascular surgery, or iatrogenic vessel perforation. Suggestions for the use of thrombolysis in high risk patients and following iatrogenic complications are discussed.

Aged↗
PubMed1991

Conjugates of ursodeoxycholate protect against cholestasis and hepatocellular necrosis caused by more hydrophobic bile salts. In vivo studies in the rat.

The protective effect of ursodeoxycholate conjugates against bile salt hepatotoxicity was studied in chronic bile fistula rats. Taurochenodeoxycholate or taurodeoxycholate, infused intraduodenally at 24 or 16 mumols/100 g rat per hour, respectively, caused cholestasis and severe hepatocellular necrosis within 8 hours. In contrast, tauroursodeoxycholate or taurocholate at 48 mumols/100 g rat per hour were choleretic. Tauroursodeoxycholate was not hepatotoxic, whereas taurocholate produced moderate hepatocellular necrosis. Simultaneous infusion of tauroursodeoxycholate to rats receiving taurochenoxycholate or taurodeoxycholate preserved bile flow and ameliorated hepatic injury in a dose-dependent manner. Tauroursodeoxycholate protected equally by intravenous and intraduodenal routes. Intravenous glycoursodeoxycholate also was protective. The hydrophobicity index of infused bile salts correlated well with their toxicity. Concurrent administration of ursodeoxycholate conjugates did not reduce biliary recovery of intraduodenally infused [24-14C]-taurocholate. Biliary alkaline phosphatase secretion was stimulated by infusion of taurocholate, taurodeoxycholate, or taurochenodeoxycholate; simultaneous infusion of ursodeoxycholate conjugates failed to prevent this increase. We conclude that ursodeoxycholate counteracts hepatoxicity of more hydrophobic bile salts via a direct effect at the level of the liver.

Animals↗
PubMed1984

A solution to the genetic and environmental puzzles of insulin-dependent diabetes mellitus.

Studies of the segregation of heterozygous immunoglobulin allotypes in families with several cases of insulin-dependent diabetes mellitus (IDDM) show that germline heavy-chain V (variable region) genes are not major genetic determinants for IDDM, but data for IDDM and Graves' disease together suggest involvement of kappa light-chain V genes. Absence of IDDM at birth, the semi-random age of onset, and the 50% discordance of identical twins suggest that somatic mutation of germline V genes is involved in the development of the pathogenetic anti-beta-cell clones. The effect of histocompatibility and other alloantigens on the prevalence of IDDM is readily accounted for by the effect of the "holes" they induce, by natural tolerance, in the immune response repertoire; these alterations apparently affect the chance of emergence of anti-beta-cell clones by the somatic mutations and network of interclonal deletions that constantly change the fringes of the repertoire. Histocompatibility antigens can also influence repertoire development by changing the specificity of conjoint presentation of foreign antigens by macrophages. Antigenic stimulation by particular environmental microorganisms is probably essential to the repertoire development necessary for the occurrence of IDDM. Additionally, beta-cell damage by local infection may play a part by facilitating autoantigen presentation to the immune system.

Antigens, Viral↗
PubMed1971

New class of purine mutants of Chinese hamster ovary cells.

Mutants of Chinese hamster ovary cells (CHO/Pro(-)) were isolated after mutagenesis with N-methylnitrosoguanidine and selection by the bromodeoxyuridine technique. Six of these were mutants classified as purine-requiring. The metabolic block appears to be early in the purine biosynthetic pathway. The mutants do not appear to be genetically identical.

Animals↗