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Biomedical subjects

C Allen

Publications and source records attributed to C Allen.

At least 253 records · Page 14Linked to original sources
PubMed1968

The maximum oxygen intake. An international reference standard of cardiorespiratory fitness.

Lack of cardiorespiratory fitness may well contribute to the increasing prevalence of degenerative cardiovascular disease throughout the world. As a first step towards co-ordinated and internationally comparable investigation of this problem, methods of measuring the reference standard of cardiorespiratory fitness-the maximum oxygen intake, (Vo(2))(max)-were compared by an international working party that met in Toronto in the summer of 1967.Repeated testing of 24 subjects showed that the (Vo(2))(max) was greatest on the treadmill, 3.4% smaller in a stepping test, and 6.6% smaller during use of a bicycle ergometer. There were also parallel differences in cardiac stroke volume. Uphill treadmill running was recommended for the laboratory measurement of (Vo(2))(max), and stepping or bicycle exercise for field studies. A discontinuous series of maximum tests caused some improvement in the fitness of subjects, and a "continuous" test (with small increases in load at 2-min intervals) was preferred.

Adult↗
PubMed1968

Standardization of submaximal exercise tests.

It is often impossible to measure the reference standard of cardiorespiratory fitness (the maximum oxygen intake) directly, and there is thus a need for subsidiary standard procedures based on body responses to submaximal exercise. In order to reach agreement on such procedures, a recent international working party has compared a variety of possible tests involving step, bicycle, and treadmill exercise; criteria of comparison included the extent of habituation and learning with each procedure, the physiological responses, and practical considerations. There was little to commend submaximal exercise on the treadmill. Anxiety and learning were least on the bicycle ergometer, but significant anaerobic metabolism developed at loads of more than 55% of aerobic power; the main role of the bicycle was thus in laboratory tests requiring arm immobilization. The step test was cheap and portable, subjects showed relatively little anxiety or learning, and good-quality electrocardiograms were obtained: it thus seemed the procedure of choice for field tests. The results of all forms of submaximal test should be extrapolated to maximum oxygen intake in order to overcome difficulties arising from differences in the age and fitness of subjects. Four common extrapolation procedures, based respectively on one to four measurements of oxygen consumption and pulse rate, yielded similar predictions of maximum oxygen intake. A single progressive test, in which the exercise load was increased at the end of every third minute, gave an identical prediction of maximum oxygen intake to that obtained from a series of 4 discontinuous tests. The progressive test was thus the preferred procedure; however, in subjects with some circulatory delay, it might be necessary to replace the four 3-min loads by three 4-min loads.

Adult↗
PubMedDate not supplied

Polycaprolactone-b-poly(ethylene oxide) block copolymer micelles as a novel drug delivery vehicle for neurotrophic agents FK506 and L-685,818.

Micelles formed from polycaprolactone-b-poly(ethylene oxide) (PCL-b-PEO) diblock copolymers were investigated as a novel drug delivery system. The affinity of the micelles for hydrophobic solubilizates was assayed by determining the partition coefficient for the lipophilic compound, pyrene, between the micelles and water; the partition coefficient was found to be on the order of 10(2). The Trypan blue and Alamar blue survival assays were used to assess the in vitro biocompatibility of the micelles with PC 12 cells, MCF-7 breast cancer cells, and primary cultures of human microglia, astrocytes, and cortical neurons. The micelles were then studied as a delivery vehicle for the neurotrophic agents FK506 and L-685,818 in PC 12 cell cultures. In both cases, the micelle-incorporated drugs, in the presence of nerve growth factor (5 ng/mL), were able to promote the degree of differentiation of the PC 12 rat pheochromocytoma cells.

Animals↗
PubMedDate not supplied

PCL-b-PEO micelles as a delivery vehicle for FK506: assessment of a functional recovery of crushed peripheral nerve.

The aim of this work was to test in vivo a new block copolymer-based delivery system containing lipophilic drug FK506, known as Tacrolimus. Tacrolimus is currently used in clinics as an immunosupressant agent, and more recently it has been shown that it can exert neurotrophic effects. We prepared, characterized, and assessed polycaprolactone-b-polyethylenoxyde (PCL-b-PEO) micelles containing FK506 in vitro and in vivo. By using well-established animal model of peripheral nerve injury (crushed sciatic nerve), we show that the rate of functional recovery of injured nerve is significantly enhanced in rats treated with micellar FK506. These findings support the notion that PCL-b-PEO is a suitable polymer material for FK506 and suggest its wider applicability as a delivery vehicle for other biologically active, poorly soluble therapeutic agents.

Animals↗
PubMedDate not supplied

Exogenous lipid pneumonia related to smoking weed oil following cadaveric renal transplantation.

A 30-year-old female presented shortly after cadaveric renal transplantation with respiratory distress typical of a bacterial infection. Following initial improvement, she developed progressive respiratory failure, initially felt to be secondary to cytomegalovirus infection. Two bronchoalveolar lavages were nondiagnostic, and an open lung biopsy was performed, which revealed a pulmonary alveolar proteinosis (PAP) reaction and exogenous lipid pneumonia (ELP). The ELP was considered to be secondary to the use of marijuana, in the form of weed oil, that was smoked daily for over 10 years and stopped just before renal transplantation. This is the first description of both PAP and ELP following renal transplantation, and the first description of ELP related to smoking weed oil. Physicians should be aware of the different forms of marijuana available and of their potential medical complications.

Adult↗