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Biomedical subjects

C J Gilbert

Publications and source records attributed to C J Gilbert.

32 records · Page 2Linked to original sources
PubMed1983

Atrioventricular sequential pacing: differential effect on retrograde conduction related to level of impulse collision.

Patients with DDD pacemakers who have intact retrograde conduction are known to be at risk of developing ventricular and "endless loop" tachycardia. To address this problem, a pacing protocol was designed in which V2A2 conduction was assessed in 16 patients during ventricular pacing alone (standard method) and during paced atrioventricular (AV) sequential drive (AV sequential method); the results were then compared. In eight of 16 patients who had intact retrograde conduction with both methods (group 1), the V2A2 intervals were significantly shorter (by 60 to 340 msec) with the AV sequential method. In the remaining eight patients, who demonstrated V2A2 block with the standard method, no V2A2 block occurred with the AV sequential method. In this study, two sets of AV intervals were programmed to produce collision of the two impulses (atrial and ventricular), either in the AV node or the His-Purkinje system (HPS). The site of V2A2 facilitation was related to the site of impulse collision. These results can be explained by earlier excitation by the atrial impulse (of AV node and/or HPS) during AV sequential pacing. However, in some cases it was evident that antegrade propagation of the atrial impulse was responsible for subsequent facilitation. The data suggest that assessment of retrograde conduction in candidates for DDD pacemakers can be made most accurately by the AV sequential method.

Adult↗
PubMed1982

Procainamide and retrograde atrioventricular nodal conduction in man.

Recent studies that show a depressant effect of procainamide (PA) on retrograde conduction in patients with atrioventricular (AV) nodal reentrant tachycardia (RT) have suggested possible incorporation of AV nodal bypass tracts. Electrophysiologic effects of i.v. PA, 10 mg/kg, on retrograde AV nodal conduction were examined in 13 patients without RT, demonstrable AV nodal refractory period curves, or accessory pathways. Ventriculoatrial (VA) conduction was recorded before and after PA using intracardiac electrograms, incremental ventricular pacing and extrastimulation. With incremental pacing during the control, VA block occurred at a mean cycle length (CL) of 364.6 +/- 87.9 msec. After PA, VA conduction was abolished in five of 13 patients due to onset of retrograde block in the AV node; in seven of 13, VA block occurred at a longer paced CL after PA (344.2 +/- 51.2 msec vs 477.1 +/- 93.2 msec). In one patient, PA did not affect VA conduction. PA invariably produced prolongation in the VA interval at comparable CL of pacing. With ventricular premature stimulation, the retrograde H2A2 intervals during the control period were short (less than 50 msec) in seven of 13, intermediate (60-100 msec) in three of 13 and long (greater than 100 msec) in three of 13 cases. PA either abolished H2A2 conduction (H2 but no A2) or prolonged the H2A2 intervals by 5-20 msec in most cases in this series. The data suggest that i.v. PA almost uniformly depresses retrograde AV nodal conduction in the intact human heart. This depressant response to PA is not indicative of presence of partial or complete AV nodal bypass tracts.

Aged↗
PubMed1976

Hypothalamic-pituitary function in patients with craniopharyngiomas.

Hypothalamic-pituitary function was investigated in 20 patients with craniopharyngioma, and all showed some degree of hypopituitarism. Pituitary-adrenal dysfunction was present in 50% of the patients whereas all but one had deficiencies of growth hormone and gonadotropin. Serum thyroxine was low in 13 patients, and in a further six there was an abnormal response of thyrotropin (TSH) to thyrotropin-releasing hormone (TRH). Prolactin levels were normal in over half the patients tested and only moderately elevated in the remainder. Gonadotropins failed to increase adequately after gonadotropin-releasing hormone (LRH) in all but one patient, and the response gave no indication of the predominantly hypothalamic site of the tumors.

Adolescent↗
PubMedDate not supplied

Peripheral blood progenitor cell transplantation for breast cancer: pharmacoeconomic considerations.

The recent observation that mobilized peripheral blood progenitor cells (PBPCs) can be used as a source of hematopoietic support has had a major effect on the cost and morbidity associated with bone marrow transplantation in patients with breast cancer. The pharmacoeconomic impact of this new technology is especially evident when secondary costs are analyzed. We see a reduction in hospital stay, decreased use of resources such as platelet transfusions and antibiotics, and long-term quality life-years gained for those patients benefiting from this therapy. Experienced transplant centers have found that the direct cost of high-dose chemotherapy using filgrastim and PBPC support is reduced as much as 50% to the patient or their insurance company. Pharmacists will play a key role in optimizing the benefits of PBPC transplantation, particularly because this therapy is moving to the outpatient arena. This article will review the pharmacoeconomic impact of PBPC transplantation primarily in terms of secondary cost measures and quality of life and discuss the limited direct cost data available and the impact of this therapy on pharmacy practice.

Antineoplastic Combined Chemotherapy Protocols↗
PubMedDate not supplied

The pharmacologic effects of recombinant, human colony-stimulating factors and their modulation by theophylline.

STUDY OBJECTIVES: To investigate the effect of colony-stimulating factors (CSFs) on drug metabolism using theophylline as a substrate (phase I), and to evaluate the influence of theophylline on endogenous serum cytokine concentrations (phase II). DESIGN: Open-label, prospective study. SETTING: The bone marrow transplant unit of a tertiary university teaching hospital. PATIENTS: Thirty-seven women with breast cancer (28 phase I, 9 phase II). INTERVENTIONS: Patients received aminophylline 0.58 mg/kg either as a 30-minute intravenous infusion before receiving recombinant CSFs or after several days of CSF therapy, just before high-dose chemotherapy (phase I) or as a continuous intravenous infusion after bone marrow transplantation (phase II). MEASUREMENTS AND MAIN RESULTS: Clearance of theophylline was significantly higher after CSF administration (0.76 vs 0.99 ml/min/kg, p = 0.019). Continuous infusion of aminophylline resulted in elevations of serum macrophage-CSF and interleukin 6. CONCLUSIONS: Administration of CSFs before autologous bone marrow transplantation for priming progenitor cells may alter drug metabolism. Studies should be conducted to evaluate the potential effects of CSFs on the disposition of chemotherapeutic agents.

Adult↗