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Biomedical subjects

R Fox

Publications and source records attributed to R Fox.

At least 127 records · Page 7Linked to original sources
PubMed1996

A randomized study of high-dose cytarabine in induction in acute myeloid leukemia.

High-dose cytarabine (ara-c) may overcome cytarabine resistance in leukemic blasts. It has been used as a successful salvage and in postremission therapy but not as initial induction treatment. Patients aged 15 to 60 years, presenting with newly diagnosed acute myeloid leukemia (AML) were randomized to receive either high-dose cytarabine, 3 g/m2 12 hourly on days 1, 3, 5, and 7 for 8 doses, daunorubicin 50 mg/m2 days 1 to 3, etoposide 75 mg/m2 days 1 to 7, (HIDAC-3-7) or standard dose cytarabine 100 mg/m2 continuous intravenous infusion for 7 days with daunorubicin and etoposide at the same dose and schedule as above (7-3-7). Patients could receive a second or third induction course if complete remission (CR) was not achieved. All patients received the same postinduction consolidation therapy (5-2-5) for 2 courses. Eligible patients had no prior chemotherapy or myelodysplastic disease. Patients have been followed for a median of 4.5 years. Of 301 patients treated, complete response (CR) was achieved in 71% with HIDAC-3-7 and 74% with 7-3-7. For patients in CR, the estimated median remission duration was 45 months with HIDAC-3-7 and 12 months with 7-3-7 (P = .0005 univariate analysis, P = .0004 multivariate analysis). The estimated percentage of patients relapse free 5 years after achieving a CR was 49% on HIDAC-3-7 and 24% on 7-3-7. Patients in CR tended to survive longer with HIDAC-3-7 but there were no overall survival differences between the two arms. HIDAC-3-7 was associated with significantly more toxicity in induction with more leukopenia, thrombocytopenia, nausea, and vomiting and eye toxicity (all P < .001) but a similar incidence of severe central nervous system and cerebellar toxicity compared to 7-3-7. The consolidation treatment was the same in both arms but caused significantly more leukopenia and thrombocytopenia in patients previously treated with HIDAC-3-7 induction (P < .0001). We conclude that a dose-effect exists for cytarabine in AML and that HIDAC-3-7 prolongs remission duration and disease-free survival and is tolerable when used as initial induction therapy in patients with de novo AML.

Acute Disease↗
PubMed1996

Disparity tuning of the stereoscopic (cyclopean) motion aftereffect.

Across five experiments this study investigated the disparity tuning of the stereoscopic motion aftereffect (adaptation from moving retinal disparity). Adapting and test stimuli were moving and stationary stereoscopic grating patterns, respectively, created from dynamic random-dot stereograms. Observers adapted to moving stereoscopic grating patterns presented with a given disparity and viewed stationary test patterns presented with the same or differing disparity to examine whether the motion aftereffect is disparity contingent. Across experiments aftereffect duration was greatest when adapting motion and test pattern both were presented with zero disparity and in the plane of fixation. Aftereffect declined as disparity of adapting motion and/or test pattern increased away from fixation, even under conditions in which depth position of adapt and test was equal. This argues against a relative depth separation explanation of the decline, and instead suggests that the amount of adaptable substrate decreases away from fixation.

Adaptation, Physiological↗
PubMed1996

Thrombolytic enhancement with perfluorocarbon-exposed sonicated dextrose albumin microbubbles.

Whereas low-intensity, high-frequency ultrasound (US) alone appears to cause minimal thrombolysis, US combined with air-filled microbubbles does increase the amount of urokinase (UK)-mediated clot lysis (CL). Because this phenomenon may be mediated by cavitation-induced streaming, we hypothesized that perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles, which are more stable than air-filled microbubbles, may also enhance US-induced thrombolysis. We measured the percentage CL of equally sized thrombi (1.0 +/- 0.1 mg) made from freshly drawn blood incubated for 2 hours and then exposed to 20 kHz US (0.846 MPa peak negative pressure). The thrombi were bathed in 4 ml of saline solution, UK alone (20,000 U), PESDA alone, or a combination of PESDA with UK. The percentage CL achieved with PESDA and therapeutic US was also compared with the percentage CL achieved with room air-filled sonicated dextrose albumin (RASDA) microbubbles. When compared with US alone (24% +/- 13% CL) or UK alone (17% +/- 3% CL), PESDA plus US produced significantly better CL (43% +/- 17%; p< 0.05). PESDA combined with US also produced significantly greater CL than RASDA combined with US (28% +/- 9%; p < 0.05). The optimal CL was achieved with a combination of PESDA with UK with US (60% +/- 14% CL). We conclude that PESDA microbubbles alone may be capable of inducing thrombolysis when insonified with a low-frequency transducer.

Contrast Media↗
PubMed1996

Clinical audit of ciprofloxacin use in adults admitted to hospital with gastroenteritis.

We audited the use of ciprofloxacin, before and after the introduction of simple clinical guidelines, in adults admitted to a regional infectious diseases unit with presumed gastroenteritis. The case notes of 128 consecutive adult admissions over 6 months in 1993 were reviewed and a comparable group of 125 adults in 1994 were prospectively followed. The discharge diagnosis was infective gastroenteritis in 73% of the 1993 admissions and 75% of the 1994 admissions, of whom 42% and 51% had confirmed bacterial enteropathogens. The 1994 cohort appeared to be more ill, with longer duration of symptoms prior to admission, more patients with profuse diarrhoea prior to admission, and longer mean duration of hospital stay. The proportion of patients with a discharge diagnosis of gastroenteritis who received ciprofloxacin did not change (64% in 1993, 67% in 1994) but the proportion of these patients who were subsequently found to be culture-positive rose from 54% to 68%. The proportion of patients receiving intravenous ciprofloxacin fell from 20% to 10% and the total number of doses (intravenous and oral) fell from 1027 in 1993 to 768 in 1994, with cost savings of pound 1465 over 6 months. The benefits and drawbacks of empirical use of ciprofloxacin are discussed. Our audit suggests that simple clinical guidelines can assist in identifying suitable patients for empirical antimicrobial therapy, and result in substantial cost savings.

Adult↗
PubMed1996

Microbiologic contamination of peripheral blood progenitor cells collected for hematopoietic cell transplantation.

BACKGROUND: Peripheral blood progenitor cells (PBPCs) rather than bone marrow are used increasingly to provide hematologic reconstitution when transfused after marrow-ablative chemotherapy. PBPCs often are collected via central venous catheters that have remained in place for long periods of time and that may become infected. STUDY DESIGN AND METHODS: The investigators reviewed their 5-year experience in collecting PBPCs for the prevalence of bacterial contamination. Except for cotrimoxazole therapy given to prevent Pneumocystis cariini pneumonia, patients were not given antibiotic prophylaxis. RESULTS: Each patient underwent a median of 7 (range, 2-21) PBPC collections; 0.2 percent (3/1040 collections) were culture positive for bacteria (two collections contained coagulase-negative staphylococci and one contained Serratia marcescens). All culture-positive collections were discarded; no PBPCs were culture positive at the time of thawing and transfusion. CONCLUSION: This contamination rate is below that previously reported for bone marrow harvests and platelet concentrate collections. Obtaining PBPCs through large-bore central venous catheters has not added to the risk of infection in transplant patients. A program of screening in vitro cultures and strict adherence to sterility techniques can result in very low microbiologic contamination and thus obviates the need for prophylactic antimicrobials in the PBPCs and in the patient.

Bacterial Infections↗
PubMed1996

Randomized controlled trial of a drug regimen that includes ciprofloxacin for the treatment of pulmonary tuberculosis.

The fluoroquinolones are promising new antituberculous agents. A randomized controlled trial of 200 adult patients with sputum smear-positive pulmonary tuberculosis was conducted in Tanzania. Patients received either a trial regimen (HRC) consisting of isoniazid (300 mg), rifampin (600 mg), and ciprofloxacin (750 mg) or a control regimen (HRZE) consisting of isoniazid (300 mg), rifampin (600 mg), pyrazinamide (25 mg/kg), and ethambutol (15 mg/kg). The 168 evaluable patients all had negative smears and cultures by month 6, but the time to conversion to negativity was longer for the HRC group than for the HRZE group because of the poor response of patients infected with human immunodeficiency virus (HIV) to the HRC regimen. Relapse was more frequent in the HRC group. The sterilizing activity of ciprofloxacin does not appear to be equal to that of the combination of pyrazinamide and ethambutol, but the difference in outcome was significant only among HIV-infected patients.

AIDS-Related Opportunistic Infections↗