The increase in genetic variability of a population can be selected during adaptation, as demonstrated by the selection of mutator alleles. The dynamics of this phenomenon, named second-order selection, can result in an improved adaptability of bacteria through regulation of all facets of mutation and recombination processes.

Adaptation, Physiological↗

PubMedDate not supplied

The control of blood glucose in the critical diabetic patient: a neuro-fuzzy method.

Conventional algorithms for regulating insulin infusion rates in those critical diabetic patients submitted to parenteral glucose and insulin infusions do not allow to approach near normal blood glucose (BG) levels since traditional control systems are not fully effective in complex nonlinear systems as BG control is. Thus, we applied fuzzy logic principles and neural network techniques to modify intravenous insulin administration rates during glucose infusion. Forty critically ill, fasted diabetic subjects submitted to glucose and potassium infusion entered the study. They were randomly assigned to two treatment regimes: in group A, insulin infusion rates were adjusted, every 4 h at any step between -1.5 and +1.5 U/h, according to a neuro-fuzzy nomogram; in control group B, insulin infusion rates were modified according to a conventional algorithm. In group A, BG was lowered below 10 mmol/l faster than in group B (8.2+/-0.7 vs. 13+/-1.8 h, P<.02). Mean BG was 7.8+/-0.2 in group A and 10.6+/-0.3 mmol/l in group B (P<.00001). BG values below 4.4 mmol/l were: A=5.8% and B=10.2%. BG values lower than 2.5 mmol/l had never been observed. In conclusion, the neuro-fuzzy control system is effective in improving the BG control in critical diabetic patients without increasing either the number of BG determinations or the risk of hypoglycemia.

Adult↗

PubMedDate not supplied

A computer assisted approach for monitoring and planning biological reconstructions in orthopaedic oncology: preliminary results and future perspectives.

The evaluation of the mechanical strength of a reconstructed bone, and its evolution during the follow-up is, at present, almost impossible. This information, however, may prove extremely useful in clinical practice, both in the surgical planning and in the management of the rehabilitation therapy. In this work, a non-invasive technique, based on the use of finite element modelling, is presented that allows the simulation of the mechanical behaviour of a skeletal reconstructions starting from Computed Tomography data. This method was applied to study the evolution, during the first year of follow-up, of the strength of the reconstructed femur of a ten year-old child if a short, slow, level walk were allowed. The preliminary results indicate that the window sculpted by the surgeon to allow the anastomosis of the vascular pedicle acts as a stress concentrator and that the reduced bone mineral density, induced in the child's bone by the absence of load during the post-operative period, increases the stress level in the proximal femur.

Bone Neoplasms↗

PubMedDate not supplied

[Fetal atrioventricular blood flow velocity in the 2nd half of pregnancy: a Doppler echocardiographic study].

Pulsed Doppler velocimetry of both fetal atrioventricular valves derived in the four-chamber-view were performed in 94 uncomplicated pregnancies between the 20th and the 40th week of gestation. The maximal velocities in early (E-peak) and late diastole (A-Peak) as well as the E/A Ratio were calculated for both tricuspid (TV) and mitral valves (MV). Normal ranges for the six measured parameters were constructed and correlated with gestational age. In the second half of pregnancy an increase of the E-wave for both valves was found (TV r = 0,59; MV r = 0,48) with higher values through the TV compared with the MV. In comparison the A-velocities showed a flat increase during the observation time (TV r = 0,32, MV r = 0,24). The E/A Ratio for both valves which is < 1 in the fetus showed an increase throughout pregnancy, mainly due to the increase of the E-wave in the observed period of time. These intracardiac Doppler flow measurements enable an insight into the physiology of fetal circulation. They give a basis for the analysis of blood flow under pathological conditions, like in congenital heart defects or in intrauterine growth retardation.

Blood Flow Velocity↗