Os jovens e a saude reprodutiva: uso do condom entre estudantes universitários / Youth and reproductive health: condom use among college students

Entre os apectos que caracterizam a morbi-mortalidade no grupo de jovens e dos adolescentes é marcante a presença dos agravos à saúde relacionados com a esfera da vida reprodutiva...

O adolescente e a saúde: direito e cidadania após a Constituição Federal de 1988 / The teenager and health: law and citizenship after the Federal Constitution of 1988

A situação da morbi-mortalidade entre os adolescentes se caracteriza pelos altos índices de causas violentas, especialmente devidas a homicídios, quanto a saúde reprodutiva, as complicações da gravidez representam um grave fator de risco para os adolescentes...

Experimental investigation of the flow induced by artificial cilia.

The fluid transport produced by rectangular shaped, magnetically actuated artificial cilia of 70 µm length and 20 µm width was determined by means of phase-locked Micro Particle Image Velocimetry (µPIV) measurements in a closed microfluidic chamber. The phase-averaged flow produced by the artificial cilia reached up to 130 µm s(-1) with an actuation cycle frequency of 10 Hz. Analysis of the measured flow data indicate that the present system is capable of achieving volume flow rates of V[combining dot above](cilia) = 14 ± 4 µl min(-1) in a micro channel of 0.5 × 5 mm(2) cross-sectional area when no back pressure is built up. This corresponds to an effective pressure gradient of 6 ± 1 Pa m(-1), which equals a pressure difference of 0.6 ± 0.1 mPa over a distance of 100 µm between two rows of cilia. These results were derived analytically from the measured velocity profile by treating the cilia as a thin boundary layer. While the cilia produce phase-averaged velocities of the order of O(10(2)µm s(-1)), time-resolved measurements showed that the flow field reverses two times during one actuation cycle inducing instantaneous velocities of up to approximately 2 mm s(-1). This shows that the flow field is dominated by fluid oscillations and flow rates are expected to increase if the beating motion of the cilia is further improved.

[Reduction of the immunological rejection in composite tissue allotransplantation by heat stress preconditioning]. / Reduktion der immunologischen Abstoßungsreaktion in Composite Tissue Allotransplantation durch Hitzeschock-Präkonditionierung.

BACKGROUND: In spite of great advances in the field of composite tissue allotransplantations (CTA), there is still a major need for optimisation in terms of immunosuppression. Heat shock proteins are produced as a reaction of the body during a stress situation. Once elevated, they protect against a second stress and reduce ischaemia-reperfusion injury within transplantations. In the literature the effect of heat shock and HSP70 on rejection after CTA has not been described. The purpose of this experimental study was to examine the effect of heat shock proteins on rejection in a rat model of CTA. Evaluated was the effect of preconditioning by prior heat stress. METHODS AND MATERIALS: Brown Norway rats were systemically heated to a core temperature of 42 °C in order to up-regulate HSP70. The expression of HSP70 in muscle was measured by Western blot analysis and showed a peak 24 h after heat shock. Allogeneic hindlimb transplantations were performed between Brown Norway rats (donor) and Lewis rats (recipients). Group 1 (n=12) was preheated 24 h prior to transplantation. In group 2 (n=12) the transplantation was performed without prior heat shock. Group 3 (n=6) was used as a control group with syngeneic hindlimb transplantations between Lewis rats. Postoperatively the appearance of the transplanted hindlimb was evaluated every 12 h. The beginning of rejection was defined when plantar erythema and foot oedema could be observed at the same time. To verify these discrete signs of rejection, the observation was continued for a further 24 h. In this time erythema and oedema spread over the whole transplanted hindlimb. The rat was sacrificed after specimens of skin and muscle had been taken for histological assessment. RESULTS: The rejection in group 1 (with preconditioning heat shock) began after 4.83±0.44 days, in group 2 (without heat shock) already after 3.88±0.53 days. The difference between these groups was significant because of the small standard deviation (Whitney-Mann U test: p<0.01). CONCLUSION: In our model of allogeneic composite tissue transplantation, a heat shock and subsequent up-regulation of HSP70 led to a significant delay of the immunological rejection. As the graft rejection is an important item influencing the outcome of allogeneic transplantations, these results represent an option to improve the final functional outcome of composite tissue allotransplantations.

Magnetically-actuated artificial cilia for microfluidic propulsion.

In this paper we quantitatively analyse the performance of magnetically-driven artificial cilia for lab-on-a-chip applications. The artificial cilia are fabricated using thin polymer films with embedded magnetic nano-particles and their deformation is studied under different external magnetic fields and flows. A coupled magneto-mechanical solid-fluid model that accurately captures the interaction between the magnetic field, cilia and fluid is used to simulate the cilia motion. The elastic and magnetic properties of the cilia are obtained by fitting the results of the computational model to the experimental data. The performance of the artificial cilia with a non-uniform cross-section is characterised using the numerical model for two channel configurations that are of practical importance: an open-loop and a closed-loop channel. We predict that the flow and pressure head generated by the artificial cilia can be as high as 18 microlitres per minute and 3 mm of water, respectively. We also study the effect of metachronal waves on the flow generated and show that the fluid propelled increases drastically compared to synchronously beating cilia, and is unidirectional. This increase is significant even when the phase difference between adjacent cilia is small. The obtained results provide guidelines for the optimal design of magnetically-driven artificial cilia for microfluidic propulsion.