Spiral formation at the microscale by µ-pyro-electrospinning.

Spiral shapes occur frequently in nature as in the case of snail shells or the cochlea - the auditory portion of the inner ear. They also inspire many technological devices that take advantage of this geometry. Here we show that µ-pyro-electrospinning is able to control whipping instabilities in order to form spiralling fibres (down to 300 nm thick) directly on a support with true microscale regularity. The results show that polymer concentration plays a key role in producing reliable and long spirals. We investigate the cell response to these spiral templates that, thanks to their true regularity, would be useful for developing innovative cochlea regeneration scaffolds.

Pyroelectric Effect Enables Simple and Rapid Evaluation of Biofilm Formation.

Biofilms are detrimental to human life and industrial processes due to potential infections, contaminations, and deterioration. Therefore, the evaluation of microbial capability to form biofilms is of fundamental importance for assessing how different environmental factors may affect their vitality. Nowadays, the approaches used for biofilm evaluation are still poor in reliability and rapidity and often provide contradictory results. Here, we present what we call biofilm electrostatic test (BET) as a simple, rapid, and highly reproducible tool for evaluating in vitro the ability of bacteria to form biofilms through electrostatic interaction with a pyroelectrified carrier. The results show how the BET is able to produce viable biofilms with a density 6-fold higher than that on the control, after just 2 h incubation. The BET could pave the way to a rapid standardization of the evaluation of bacterial resistance among biofilm-producing microorganisms. In fact, due to its simplicity and cost-effectiveness, it is well suited for a rapid and easy implementation in a microbiology laboratory.

Easy Printing of High Viscous Microdots by Spontaneous Breakup of Thin Fibers.

Electrohydrodynamic jetting is emerging as a successful technique for printing inks with resolutions well beyond those offered by conventional inkjet printers. However, the variety of printable inks is still limited to those with relatively low viscosities (typically <20 mPa s) due to nozzle clogging problems. Here, we show the possibility of printing ordered microdots of high viscous inks such as poly(lactic-co-glycolic acid) (PLGA) by exploiting the spontaneous breakup of a thin fiber generated through nozzle-free pyro-electrospinning. The PLGA fiber is deposited onto a partially wetting surface, and the breakup is achieved simply by applying an appropriate thermal stimulation, which is able to induce polymer melting and hence a mechanism of surface area minimization due to the Plateau-Rayleigh instability. The results show that this technique is a good candidate for extending the printability at the microscale to high viscous inks, thus extending their applicability to additional applications, such as cell behavior under controlled morphological constraints.

Allometry of hepatic weight growth in human staged fetuses.

The growth of the hepatic weight was correlated to fetal parameters of maturity (gestational age, crown-rump length and weight) in 70 human fetuses ranging from 14 to 39 weeks post-conception using the allometric method. The growth of the hepatic weight presents moderate positive allometry relative to age and C-R length, and isometry relative to fetal weight. The coefficiens of correlation are very high (p less than 0.001, Table 1). This study presents growth curves of the hepatic weight useful in medical branches such as anatomy, forensic medicine, fetopathology, medical imagery, onstetrics and pediatrics.

[Quantitative Growth of the human fetal larynx: allometric study between the 9th and 38th weeks post-conception]. / Crescimento quantitativo da laringe fetal humana: estudo alométrico entre a 9a feminine e a 38a feminine semanas pós-concepção.

The ponderal growth of the larynx was studied in human fetal period between the 9th and 38th weeks post-conception (w.p.c.). The larynx weight (in grams - g) was related with body weight (in grams -g) using the allometric equation Y= ax(b). Our results indicated that relative growth of the larynx is allometric negative (b= 0.55, p < 0.001). These data are important in estimating the fetal gestational age after non-invasive investigation (MR, CT and ultrasound).

[Relative growth of the human cerebellum: a quantitative estimate]. / Croissance relative du cervelet humain: une estimation quantitative.

The relative growth of the cerebellum was studied in 300 human foetuses by using of the equation Y = bxk. The cerebellum weight was correlated to the cephalic perimeter and to the fetal weight. The relative growth of the cerebellum presented positive allometry (k = 3.3; k = 1.3 respectively). Masculine foetus presented greater index than feminine foetus.

[Prenatal growth of the human skull: quantitative study]. / Croissance prénatale du crâne humain: étude quantitative.

The relative growth of the skull was studied in 300 human foetuses by using of the allometric equation Y = aXb. The skull growth was correlated to the crown-rump length and to the fetal weight. The relative growth of the skull presented positive allometry. Masculine foetus presented greater index than feminine foetus.

Spleen's relative growth in human fetuses.

The growth of the spleen weight was studied by bivariate allometry. It was correlated to fetal parameters of development as gestational age (in weeks), crown-rump length (mm) and weight (gm). Thirty human fetuses ranging from 16 to 36 weeks were studied. These were analysed in second and third trimesters separately and together. The growth of the spleen weight presents statistically significant positive allometry relative to age, C-R length and fetal weight. In second trimester the allometric coefficient, analysing spleen's weight and fetus' weight, calculated by reduced major axis method (RMA) was 1.21. In the third one the RMA was 1.73. Considering fetuses together the RMA = 1.65. This study presents growth curves of the spleen weight useful in medical branches such as anatomy, forensic medicine, medical imagery, fetophatology, obstetrics and pediatrics.

Quantitative growth of the eye in the human fetus.

Eye weight growth was studied in 50 human fetuses aged 14 to 39 weeks after conception. The collected date was correlated with fetal maturity parameters (festational age and fetal weight) using the allometric method. Normal eye weight curves were obtained. The results indicate that eye weight growth present negative allometry. These curves may be important for the diagnosis of fetal eye malformations, and may indicate that noninvasive method such as ultrasounds can be used.

Relative growth of brain in the human fetuses: first gestational trimester.

The relative growth of brain weight was studied in 23 Brazilian human fixed fetuses of known age ranging from 9th to 12th weeks post-conception using the allometric method: Y = aXb. The brain weight (grams) was correlated to the fetal parameters of growth: gestational age (weeks post-conception), cephalic perimeter (millimeters) and fetal weight (grams). The brain weight growth presented negative allometry relative to fetal age (b = 0.87) and cephalic perimeter (b = 2.46) and positive allometry relative to gestational age (b = 6.65). These data are important to compare the fetal growth after ultrasonic investigation.