The correlation between ECG characteristics and hemodynamic results in isolated atrial septal defects

Electrocardiographic characteristics and haemodynamic findings in 30 patients with secundum atrial septal defects were correlated retrospectively to determine whether any haemodynamic deductions could be made based on ECG findings. Although statistically significant correlations were found, no accurate haemodynamic estimations could be made based on ECG findings.     

In vivo MRI of cancer cell fate at the single-cell level in a mouse model of breast cancer metastasis to the brain.

Metastasis (the spread of cancer from a primary tumor to secondary organs) is responsible for most cancer deaths. The ability to follow the fate of a population of tumor cells over time in an experimental animal would provide a powerful new way to monitor the metastatic process. Here we describe a magnetic resonance imaging (MRI) technique that permits the tracking of breast cancer cells in a mouse model of brain metastasis at the single-cell level. Cancer cells that were injected into the left ventricle of the mouse heart and then delivered to the brain were detectable on MR images. This allowed the visualization of the initial delivery and distribution of cells, as well as the growth of tumors from a subset of these cells within the whole intact brain volume. The ability to follow the metastatic process from the single-cell stage through metastatic growth, and to quantify and monitor the presence of solitary undivided cells will facilitate progress in understanding the mechanisms of brain metastasis and tumor dormancy, and the development of therapeutics to treat this disease.     

Body Composition Changes after a Weight Loss Intervention: A 3-Year Follow-Up Study

Studies comparing different types of exercise-based interventions have not shown a consistent effect of training on long-term weight maintenance. The aim of this study was to compare the effects of exercise modalities combined with diet intervention on body composition immediately after intervention and at 3 years’ follow-up in overweight and obese adults. Two-hundred thirty-nine people (107 men) participated in a 6-month diet and exercise-based intervention, split into four randomly assigned groups: strength group (S), endurance group (E), combined strength and endurance group (SE), and control group (C). The body composition measurements took place on the first week before the start of training and after 22 weeks of training. In addition, a third measurement took place 3 years after the intervention period. A significant interaction effect (group × time) (p = 0.017) was observed for the fat mass percentage. It significantly decreased by 5.48 ± 0.65%, 5.30 ± 0.65%, 7.04 ± 0.72%, and 4.86 ± 0.65% at post-intervention for S, E, SE, and C, respectively. Three years after the intervention, the fat mass percentage returned to values similar to the baseline, except for the combined strength and endurance group, where it remained lower than the value at pre-intervention (p < 0.05). However, no significant interaction was discovered for the rest of the studied outcomes, neither at post-intervention nor 3 years later. The combined strength and endurance group was the only group that achieved lower levels of fat mass (%) at both post-intervention and 3 years after intervention, in comparison with the other groups.     

Time-, voltage-, and state-dependent block by quinidine of a cloned human cardiac potassium channel.

The interaction of quinidine with a cloned human cardiac potassium channel (HK2) expressed in a stable mouse L cell line was studied using the whole-cell tight-seal voltage-clamp technique. Quinidine (20 microM) did not affect the initial sigmoidal activation time course of the current. However, it reduced the peak current and induced a subsequent decline, with a time constant of 8.2 +/- 0.8 msec, to 28 +/- 6% of control (at +60 mV). The concentration dependence of HK2 block at +60 mV yielded an apparent KD of 6 microM and a Hill coefficient of 0.9. The degree of block was voltage dependent. Block increased from 0.60 +/- 0.09 at 0 mV to 0.72 +/- 0.06 at +60 mV with 20 microM quinidine and from 0.39 +/- 0.20 to 0.48 +/- 0.16 with 6 microM. Paired analysis in seven experiments with 20 microM quinidine indicated that the voltage-dependent increase in block was significant (difference, 12 +/- 4%; p less than 0.001). This voltage dependence was described by an equivalent electrical distance delta of 0.19 +/- 0.02, which suggested that at the binding site quinidine experienced 19% of the applied transmembrane electrical field, referenced to the inner surface. Quinidine reduced the tail current amplitude and slowed the time course relative to control, resulting in a "crossover" phenomenon. These data indicate that 1) the charged form of quinidine blocks the HK2 channel after it opens, 2) binding occurs within the transmembrane electrical field (probably in or near the ion permeation pathway), and 3) unbinding is required before the channel can close.     

A growth model of human papillomavirus type 16 designed from cellular automata and agent-based models

ObjectiveThis paper presents a conceptual model that is developed upon a characterization of human papillomavirus type 16 (HPV16) which is used to build a simulation prototype of the HPV16 growth process.MethodologyThe human papillomavirus type 16 is the principal virus detected in invasive lesions of cervical cancer, and associated with the greater persistence and prevalence in pre-malignant and malignant lesions. The probability of acquiring an infection with HPV16 is extremely high in sexually active individuals. However, an HPV16 infection can disappear after becoming a histological confirmed case. According to the characterization of HPV16 proposed in this paper, cells as compared to a society behaves as a complex system, i.e., cells behave in a cooperative manner, following a set of rules defined by local interactions among them. Such complex system is defined by combining a cellular automaton and agent-based models. In this way, the behavior of the HPV16 is simulated by allowing the cellular automaton to follow such parameterized behavior rules.ResultsBoth cross-sectional and prospective studies indicate that HPV16 infection persistence increase the risk of high-grade CIN, as observed in the results provided by the growth simulation model of HPV16. The average growth rate extrapolated over 52 weeks (12 months) and calculated by the model showed a 37.87% growth for CIN1, 35.53% for CIN2 and 16.92% for CIN3. Remarkably, these results are similar to the results obtained and reported by clinical studies. For example, the results obtained using the proposed model for CIN2 and the results obtained by Östör [36], have a differential of 0.53 percentage points while have a differential of 2.23 percentage points with the results obtained by Insinga et al. [51]. Also, for the CIN3, the results obtained using the proposed model, have a differential of 2.92 percentage points with the Insinga et al. [52], results.ConclusionThrough the specification of parameterized behavior rules for HPV16 that are simulated under the combined technique of cellular automata and agent-based models, the HPV life cycle can be simulated allowing for observations at different stages. The proposed model then can be used as a support tool in the investigation of HPV16, in particular (as part of our future work) to develop drugs as agents in the control of the HPV16 disease.     

Breastfeeding attenuates the effect of low birthweight on abdominal adiposity in adolescents: the HELENA study

The aim of this study was to examine whether breastfeeding may reduce the programming effect of birthweight on abdominal adiposity. Abdominal (in three regions: R1, R2 and R3) adiposity was measured by dual energy x‐ray absorptiometry in 314 adolescents. Breastfeeding duration, birthweight, duration of gestation and maternal educational level were obtained from questionnaire. Physical activity was objectively measured. We detected significant interactions between breastfeeding and birthweight on abdominal adiposity (Ps = 0.02–0.07). We observed that birthweight was associated with abdominal adiposity in the group who had never been breastfed (β = ?0.19 to ?0.23; Ps < 0.05), while no association was found in adolescents who had breastfeeding for ≥3 months (β = ?0.03 to ?0.07). The results were independent of duration of gestation, age, sex, maternal educational level and physical activity. Breastfeeding may reduce the adverse influence conferred by low birthweight on abdominal adiposity in adolescents.