Biomedical subjects

J R Suárez

Publications and source records attributed to J R Suárez.

16 recordsLinked to original sources

PubMed1998

Characterizing patterns of drug-taking behavior with a multiple drug regimen in an AIDS clinical trial.

OBJECTIVE: To characterize drug-taking behavior using continuous electronic monitoring in an AIDS clinical trial. SETTING: This was a substudy of AIDS Clinical Trials Group (ACTG) protocol 175, a phase II/III study of dideoxynucleoside monotherapy versus combination therapy in asymptomatic HIV-positive subjects. Participants were required to comply with regimens containing zidovudine, zalcitabine and didanosine, or matching placebos; the total daily pill count was 16. DESIGN: For participants at two ACTG 175 sites, electronic devices were used to monitor drug-taking behavior of all study medications over a period of approximately 90 days. MEASUREMENTS: Four indices of drug-taking behavior were calculated and their distributions and relationship to the prescribed regimen were examined. RESULTS: Data from 41 subjects were analyzed. Of the prescribed doses of zidovudine, zalcitabine and didanosine, 88, 84 and 82%, respectively, were taken. Of these, 55, 66 and 79%, respectively, were taken at the prescribed dosing frequency. The median percentage of days on which participants failed to take any of the doses was 2-5%. There was a trend towards lower adherence in the combination therapy arms compared with those assigned to receive monotherapy. In this analysis, older patients demonstrated better adherence, although patient characteristics, in general, were poorly predictive of adherence. CONCLUSION: Drug-taking behavior for all three active study medications differed from that prescribed. One result of this erratic adherence was that study participants sustained little antiretroviral effect during more than 25% of the monitoring period.

Acquired Immunodeficiency Syndrome↗

PubMed1998

The extent of non-adherence in a large AIDS clinical trial using plasma dideoxynucleoside concentrations as a marker.

OBJECTIVES: To assess adherence to study medications in an AIDS clinical trial, to evaluate whether study participants adhered to only one component of a multidrug regimen ('differential adherence'), and to determine whether there was evidence of non-uniform adherence to study medications among treatment groups. SETTING: This was a substudy of AIDS Clinical Trials Group protocol 175, a large, double-blind, randomized study of monotherapy versus combination dideoxynucleoside therapy. Participants were required to adhere to a complex regimen of zidovudine, zalcitabine and didanosine, or their matching placebos. DESIGN: Between October 1992 and January 1994, study sites were selected at random, and a 1-week period was designated during which study participants attending routine clinic visits provided a blood sample and dosing history. Participants were not informed of the purpose of the substudy. MEASUREMENTS: Adherence was assessed using plasma drug concentrations and defined by the presence of detectable drug in a plasma sample obtained within a specified analysis window. RESULTS: Of 722 plasma samples analyzed, approximately 75% contained detectable concentrations of the assigned drugs and 5-14.5% contained no detectable drugs. Approximately 7 and 13% of samples from participants assigned to monotherapy arms contained non-prescribed dideoxynucleosides, and 14 and 19% assigned to combination therapies contained only one drug. CONCLUSIONS: Various non-adherence behaviors were observed, including patterns of underdosing and taking non-prescribed drugs. Non-adherence was moderate but uniform amongst the treatment groups and may have contributed to a marginal reduction in the power of the primary intent-to-treat analysis to detect differences in efficacy amongst the assigned treatments.

Acquired Immunodeficiency Syndrome↗

PubMed1995

Value of adenosine deaminase in the diagnosis of tuberculous pleural effusions in young patients in a region of high prevalence of tuberculosis.

BACKGROUND: Pleural biopsy is usually considered important for the diagnosis of pleural effusions, especially for distinguishing between tuberculosis and neoplasia, even though tuberculous pleural fluid contains sensitive biochemical markers. In regions with a high prevalence of tuberculosis, and in patient groups with a low risk of other causes of pleurisy, the positive predictive value of these markers is increased. The criteria for performing a pleural biopsy under these circumstances have been investigated, using adenosine deaminase (ADA) as a pleural fluid marker for tuberculosis. METHODS: One hundred and twenty nine patients with a pleural effusion aged < or = 35 years (mean (SD) 25.2 (4.9) years) were studied. Seventy three were men. Eighty one effusions (62.8%) were tuberculous, 12 (9.3%) parapneumonic, and 10 (7.7%) neoplastic, five were caused by pulmonary thromboembolism, four by systemic lupus erythematosus, seven by empyema, three following surgery, one was the result of asbestosis, and one of nephrotic syndrome. In five cases no definitive diagnosis was reached. ADA levels were determined by the method of Galanti and Giusti. RESULTS: The diagnostic yield of procedures not involving biopsy was 94.5% (122/129). Pleural biopsy provided a diagnosis in a further two cases, but not in the remaining five. All tuberculous cases had pleural fluid levels of ADA of > 47 U/l (mean (SD) 111.1 (36.6) U/l). The only other cases in which ADA exceeded this level were six of the seven patients with empyema. Cytological examination of the pleural fluid diagnosed eight of the 10 neoplastic cases, compared with six diagnosed by pleural biopsy. CONCLUSIONS: In a region with a high prevalence of tuberculosis procedures not involving pleural biopsy have a very high diagnostic yield in patients with a pleural effusion aged < or = 35 years, making biopsy necessary only in cases in which pleural levels of ADA are below 47 U/l, pleural fluid cytology is negative and, in the absence of a positive basis for some other diagnosis, neoplasia is suspected.

Adenosine Deaminase↗

PubMed1977

[Gastric secretion in hypovolemic rats caused by acute hemorrhage].

Gastric secretion was studied in two groups of rats in which pyloric ligature with wire was previously peformed. One of the groups was acutely bled until hypovolemia. The following parameters were checked: gastric volume, acid and pepsin secretion, Pu/g of stomach, chloride, potassium, and sodium. A significant decrease in volume, acid and pepsin secretion, Pu/g of stomach and chloride and increase in potassium in the hypovolemic rats found. There was no significant change in sodium concentration. There was no significant difference in the pepsinogen concentration in gastric mucous between both groups of rats.

Acute Disease↗

PubMed1977

[Study of gastric secretion in rats with ligation of the pylorus according to the Shay and Dai methods].

A comparative study of gastric secretion in rats with pyloric ligature according to either Shays' or Dais' methods was carried on, studying in both groups gastic acid and peptic secretions, mucous pepsinogen, and Na+, K+, and Cl-. The acid-peptic output as well as gastric Pu/g were greater in Dais' method. There were no changes regarding mucous pepsinogen when comparing both methods. Cl- and Na+ determinations showed minimal changes, whereas K+ showed no difference in both methods. We explain these modifications based on the difference in the secreted volume, since the acid concentration and Pu/ml are practically the same when comparing both methods.

Animals↗

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