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Biomedical subjects

A P Cross

Publications and source records attributed to A P Cross.

8 recordsLinked to original sources
PubMed1990

Proximal percutaneous balloon angioplasty and distal bypass for multilevel arterial occlusion. Veterans Administration Cooperative Study No. 199.

Multiple sites of atherosclerotic occlusion in high risk patients may be treated by angioplasty of the iliac obstruction and distal reconstruction. We report 18 male patients with symptomatic peripheral vascular disease in whom proximal iliac percutaneous transluminal angioplasty was combined with femoropopliteal bypass (11), femorotibial bypass (2), or femorofemoral bypass (5). There were no operative deaths. The pretreatment ankle brachial index of 0.40 +/- 0.04 was increased to 0.64 +/- 0.04 by discharge (p = 0.0001), and remained significantly increased through 27 months (0.65 +/- 0.07) (p = 0.0001). During the follow-up period of 2-57 (mean 27 months) one dilated iliac artery required repeated percutaneous transluminal angioplasty and revision of the femoropopliteal bypass at three months. Two late amputations of study limbs occurred at two years and three years due to progression of distal disease in the infrapopliteal segment. Four patients died during the follow-up period of ischemic heart disease (3) and lung carcinoma (1). Life table analysis shows a 76% success rate for the combined procedures at two years. In selected, high risk patients, proximal iliac dilatation and distal bypass is an acceptable alternative reconstruction for multilevel occlusion.

Aged↗
PubMed1989

A prospective trial of ionic vs nonionic contrast agents in routine clinical practice: comparison of adverse effects.

A multicenter study of adverse effects of ionic and nonionic contrast agents was conducted in three similar time periods. In 1985, before approval of the nonionic contrast agents by the Food and Drug Administration, 6006 consecutive patients received iv ionic agents for urography or CT. After approval of the nonionic agents, 7170 consecutive patients referred for the same examinations were studied. The two groups of patients were significantly different, but the differences were small and did not uniformly favor either group. The incidence of adverse effects in the patients given ionic contrast material was significantly higher than that of the nonionic group (4.17% vs 0.69%, p less than .001). The reactions were also more severe in the ionic group than in the nonionic group (p less than .005). A patient questionnaire disclosed that many patients did not feel well for hours to days after the procedure and also did not immediately resume normal activities of daily living. The nonionic agent was significantly less distressful than the ionic agent. We conclude that nonionic agents cause fewer and less severe adverse effects. Reducing adverse effects can save the patient or the examining site either time or money. However, this study does not show that nonionic agents are more cost-effective than ionic agents.

Contrast Media↗
PubMed1989

Percutaneous transluminal angioplasty versus operation for peripheral arteriosclerosis. Report of a prospective randomized trial in a selected group of patients.

A prospective, randomized comparison of percutaneous transluminal angioplasty (PTA) with surgery in the treatment of occlusive disease of the iliac, superficial femoral, or popliteal arteries began in 1983. Radiologists and vascular surgeons independently assessed index lesions on arteriograms to decide whether their respective treatments were appropriate. Of 263 male patients randomized, 255 received vascular intervention (surgery, 126 patients; PTA, 129 patients). The groups were comparable when stratified for systemic risk factors and anatomic distribution of disease. Because eligibility criteria required that all lesions randomized for treatment be suitable for PTA, the severity of disease was less than that of the general population having vascular disease. Claudication was the principal indication for intervention. The immediate failure rate for PTA was 15.5% (20 of 129 patients). Surgery was performed with one in-hospital death (0.8%) and 17 complications (13.5%). There were two late deaths ascribable to surgical complications and none to PTA. At 4.5 years, 50 deaths (20%) (28 from surgery; 22 with PTA) and 24 major amputations of legs included in the study (13 with surgery; 11 with PTA) have occurred. The baseline ankle-brachial indexes (ABIs) of 0.51 +/- 0.02, respectively, after treatment and was not different between the groups through 36 months (surgery, 0.28 +/- 0.04; PTA, 0.30 +/- 0.05). The 17 patients undergoing surgery after unsuccessful PTA had a mean ABI increase of 0.32 +/- 0.07; the durability of hemodynamic improvement was similar in both groups of patients.

Actuarial Analysis↗
PubMed1986

Efficacy of pneumococcal vaccine in high-risk patients. Results of a Veterans Administration Cooperative Study.

We conducted a randomized, double-blind, placebo-controlled trial to test the efficacy of the 14-valent pneumococcal capsular polysaccharide vaccine in 2295 high-risk patients (patients with one or more of the following: age above 55 years and the presence of chronic cardiac, pulmonary, renal, or hepatic disease, alcoholism, or diabetes mellitus). Seventy-one episodes of proved or probable pneumococcal pneumonia or bronchitis occurred among 63 of the patients (27 placebo recipients and 36 vaccine recipients). Vaccine-serotype Streptococcus pneumoniae strains were recovered in association with 11 infections in the placebo group and 14 infections in the vaccine group. Pneumococcal infections occurred most frequently among patients with chronic pulmonary, cardiac, or renal diseases. Among vaccine recipients who subsequently had vaccine-type pneumonia or bronchitis, the majority did not make or sustain serum antibodies against their infecting organism in concentrations that were twice as high as the base-line values, or more than 400 ng of antibody nitrogen per milliliter, although their base-line levels were higher than those in subjects in whom infection did not develop. We were unable to demonstrate any efficacy of the pneumococcal vaccine in preventing pneumonia or bronchitis in this population. Our data suggest that chronically ill patients, who are most susceptible to infection, may have an impaired immune response to the pneumococcal vaccine.

Antibodies, Bacterial↗
PubMedDate not supplied

Modelling the development of resistance of Plasmodium falciparum to anti-malarial drugs.

A hybrid transmission/genetics model for the development of resistance by Plasmodium falciparum to anti-malarial drugs is set forth. Field data on pyrimethamine resistance are used to calibrate and test the model. Simulated consequences of different drug dosage and population coverage strategies are presented to illustrate an ethical dilemma. A strategy of maximally effective treatment for all infected individuals in the short term can be deleterious--in terms of rapid development of drug resistance--for a community in the longer term.

Adolescent↗