Solutions to the Cost-of-Selection Dilemma

There are various biologically realistic ways around the cost-of-selection restriction on rapid multiple-gene substitution. Some of these ways depend upon particular forms of interaction or linkage in the genes undergoing substitution; other ways depend on particular conditions of population size and structure. The special genotypic and populational conditions required for rapid evolutionary change in genetically complex characters are not unusual in higher organisms.     

Haemodynamic changes in neurogenic pulmonary oedema: Effect of dobutamine

The haemodynamic and gas exchange abnormalities occurring in neurogenic pulmonary oedema (NPO) were examined retrospectively in 20 patients admitted to the Intensive Therapy Unit (ITU) over a 45-month period (February 1992 to November 1995). In 12 patients, where vasoactive therapy with dobutamine was employed, its effect on haemodynamics was examined. Cardiac index (CI median 2.2 l min^–1 m^–2) and left ventricular stroke work index (LVSWI 20 g.m.m^–2) were markedly depressed, while pulmonary artery wedge pressure (PAWP 17 mmHg), mean pulmonary artery pressure (MPAP 30.5 mmHg), systemic vascular resistance index (SVRI 2852 dyne.s.cm^–5.m²) and pulmonary vascular resistance index (PVRI 393 dyne.s.cm^–5.m²) were substantially elevated above normal values. Mean arterial pressure (MAP 82.5 mmHg) and heart rate (HR 102 bpm) were within normal limits. The poor oxygenation is indicated by a median PaO₂/fiO₂ ratio of 18.0 kPa. Patients treated with dobutamine showed significant increases in CI and LVSWI and significant falls in SVRI and PAWP at 2 and 6 h after institution of therapy, and there was a significant rise in PaO₂/fiO₂ ratio to 27.8 kPa at 6 h. NPO was generally associated with severe depression of myocardial function and elevation of pulmonary vascular pressures. This dysfunction was readily reversed by dobutamine.     

An evaluation of the characteristics and performance of neonatal phototherapy equipment

This paper reviews the current state of knowledge and practice in neonatal phototherapy, and assesses methods of evaluating the characteristics and performance of different equipment. Artificial lighting (usually fluorescent) has been used for the past 30 years in the treatment of neonatal jaundice. Widely differing light outputs and spectra are used, making comparison and evaluation difficult for clinicians. Manufacturers of neonatal phototherapy equipment have no standard for assessing the performance of their equipment, and information that is supplied is at best confusing or deceptive to the users. Best practice is usually based on empirical data from equipment in use, but there is wide agreement that present phototherapy is sub-optimal, i.e. does not achieve maximum rate of bilirubin clearance for minimum therapeutic dose. Several studies in the last ten years have emphasized the importance of both the wavelength and intensity of light for optimal phototherapy. These are discussed and a technique is proposed for normalizing the output of different systems to make comparison easier and to enable optimal treatments to be designed.