The use of internet-based social media as a tool in enhancing student’s learning experiences in biological sciences

This study explored the use of social media as a tool in enhancing student’s learning experiences, by using online instruction as a supplement to a face-to-face general education course, such as biological sciences. Survey data were collected from 186 students who were enrolled in a Biological Sciences course. The course was taught in a blended format using Facebook and Edmodo online social networks. A four point Likert scale was used to interpret the data collected. Findings indicated that, when traditional face-to-face instruction was combined with online components, students’ learning was enhanced. Findings from this study indicate that students had better experience, better engagement, and appreciated both the social learning experience gave by the online social network. Results revealed that students through student-student interaction and student-teacher interaction enhance their own experiences and improved their learning ability. The findings were used as bases in developing new practices and methodologies involving social networking tools for learning. Moreover, findings were used to design a blended format syllabus and blended learning guidelines. DOI: 10.18870/hlrc.v3i4.17

Matrix Metalloproteinase-3 (MMP-3) Is an Endogenous Activator of the MMP-9 Secreted by Placental Leukocytes: Implication in Human Labor.

BACKGROUND:The activity of matrix degrading enzymes plays a leading role in the rupture of the fetal membranes under normal and pathological human labor, and matrix metalloproteinase-9 (MMP-9) it is considered a biomarker of this event. To gain further insight into local MMP-9 origin and activation, in this study we analyzed the contribution of human placental leukocytes to MMP-9 secretion and explored the local mechanisms of the pro-enzyme activation. METHODS:Placental blood leukocytes were obtained from women at term gestation without labor and maintained in culture up to 72 h. MMP-9 activity in the culture supernatants was determined by zymography and using a specific substrate. The presence of a potential pro-MMP-9 activator in the culture supernatants was monitored using a recombinant biotin-labeled human pro-MMP-9. To characterize the endogenous pro-MMP-9 activator, MMP-1, -3, -7 and -9 were measured by multiplex assay in the supernatants, and an inhibition assay of MMP-9 activation was performed using an anti-human MMP-3 and a specific MMP-3 inhibitor. Finally, production of MMP-9 and MMP-3 in placental leukocytes obtained from term pregnancies with and without labor was assessed by immunofluorescence. RESULTS:Placental leukocytes spontaneously secreted pro-MMP-9 after 24 h of culture, increasing significantly at 48 h (P≤0.05), when the active form of MMP-9 was detected. Culture supernatants activated the recombinant pro-MMP-9 showing that placental leukocytes secrete the activator. A significant increase in MMP-3 secretion by placental leukocytes was observed since 48 h in culture (P≤0.05) and up to 72 h (P≤0.001), when concentration reached its maximum value. Specific activity of MMP-9 decreased significantly (P≤0.005) when an anti-MMP-3 antibody or a specific MMP-3 inhibitor were added to the culture media. Placental leukocytes from term labor produced more MMP-9 and MMP-3 compared to term non-labor cells. CONCLUSIONS:In this work we confirm that placental leukocytes from human term pregnancies are able to secrete large amounts of MMP-9, and that the production of the enzyme it is enhanced by labor. We also demonstrate for the first time that endogenous MMP-3 plays a major role in MMP-9 activation process. These findings support the contribution of placental leukocytes to create the collagenolytic microenvironment that induces the rupture of the fetal membranes during human labor

MMP-9 and MMP-3 are produced in large amounts during labor.

<p>Representative immunofluorescence images showing MMP-9 or MMP-3 immunolocalization in placental leukocytes obtained from term labor and non-labor women after 48 h of culture. Each panel shows Evans blue contrast staining (red) (upper left), MMP-9 or MMP-3 (green) (upper right), Nomarski interference contrast (lower left), and merge (lower right). Placental leukocytes from term labor produce more MMP-9 and MMP-3 compared to term non-labor cells. Confocal microscopy 40X.</p

A natural activator of proMMP-9 is present in supernatants of placental leukocyte cultures.

<p>Representative western blot showing increasing activation of the exogenous recombinant proMMP-9 incubated in placental leukocyte supernatants. Three different supernatants were run in duplicate.</p

MMP-9 activity increases in placental leukocyte supernatants in a time-dependent manner.

<p>Specific substrate assay showed a significant increase in MMP-9 activity in the placental leukocyte supernatants along the culture, reaching the major activity at 72h. Each point represents the mean ± SD of 3 independent experiments in duplicate. *<i>P</i>≤0.05, **<i>P</i>≤0.005</p

MMP-3 increments in placental leukocyte supernatants along the culture.

<p>Multiplex assay was performed in placental leukocyte supernatants to measure MMP-1, MMP-3, MMP-7 and MMP-9. MMP-3 showed a significant increase at 48 and 72h, while the other MMP-s did not significantly change. Bars represent mean ± SD of five independent experiments in duplicate. *<i>P</i>≤0.05, ***<i>P</i>≤0.001</p

MMP-9 activation is inhibited by MMP-3.

<p>Cultures of placental leukocytes were incubated in the presence or absence of a neutralizing anti MMP-3 or a specific MMP-3 inhibitor. Culture media analyzed by gelatin zymography shows that the 82 kDa active form of MMP-9 disappears in the presence of the anti MMP-3 antibody at 24, 48 and 72 h (panel A representative gel, n = 3). MMP-9 activation is abolished by the specific MMP-3 inhibitor; each point represents the mean ± SD (**<i>P</i><0.005) (panel B, n = 3).</p

Placental leukocytes in culture secrete pro-enzyme and active MMP-9.

<p>A) Representative gelatin zymography (0.5 μg protein per lane) of placental leukocyte supernatants shows the 92 kDa pro-enzyme and the 82 kDa active form of MMP-9. B) The bars represent the optical densities (OD) of pro-enzyme and active MMP-9. While the pro-enzyme increased after 24h in supernatants, the active form was increased significantly only after 48h of culture. Seven independent experiments in duplicate are expressed as mean ± SD. *<i>P</i>≤0.05, **<i>P</i>≤0.005</p

Placental leukocytes remain viable and functional during culture.

<p>A) XTT viability assay, time 0 was consider as 95% of viability according to trypan blue staining. B) IL-1b ELISA in the supernatants of placental leukocytes along the culture used as functionality assay. Placental leukocytes in culture remain viable (around 90%) and secreting IL-1b from 24 to 96 h, which was the culture period for all the experiments. Three independent experiments in duplicate are expressed as mean ± SD. *<i>P≤</i>0.05 compared to time 0 (A) or 24 h (B).</p