Analysing students' shared activity while modeling a biological process in a computer-supported educational environment

Abstract  This paper reports on a case study with three dyads of high school students (age 14 years) each collaborating on a plant growth modeling task in the computer-supported educational environment ' ModelsCreator '. Following a qualitative line of research, the present study aims at highlighting the ways in which the collaborating students as well as the facilitator who supported them are engaged in the computer-based modeling 'activity'. The analysis is carried out with a two-level analytic tool that has been derived within the theoretical framework of 'activity theory'. Our results show that a wide range of modeling 'operations' is activated in the context of the three major modeling 'actions' of 'analysis', 'synthesis' and 'testing-interpreting', which take place in the light of the facilitator-driven 'action' of cognitive and technical support. Moreover, these actions are combined into 'modeling units' of various forms which are repeated several times until the modeling process comes to an end. These many-fold repeats of the 'modeling unit' appear to shape a pattern which characterizes the computer-supported shared 'activity' as a whole.     

Mutations and expression of the ras family genes in leukemias

The levels of expression and the incidence of codon 12 point mutations of the ras family genes were studied in 18 cases of leukemia, seven with acute myeloblastic leukemia (AML), three with acute lymphoblastic leukemia (ALL), four cases with chronic myelogenic leukemia (CML) and four cases with chronic lymphocytic leukemia (CLL). Elevated expression of the ras genes was found for 39%, 61% and 67% of the specimens for the H-ras, K-ras and N-ras, respectively. A trend was found between the overexpression of the N-ras gene and the acute leukemias: all 10 acute leukemias exhibited overexpression of the N-ras gene, while only two of the CML cases, both in blastic crisis, showed elevated levels of the N-ras gene. Codon 12 point mutations at the N-ras gene were found in two of seven cases (28%) with AML and one of four cases (25%) with CML. The only K-ras codon 12 point mutation was found in a patient with CLL. No mutations were found in the codon 12 of H-ras. Our data suggest that apart from the point mutations, overexpression of the ras family genes is important in the development of the disease.     

Glucocorticoid and estrogen receptors have elevated activity in human endometrial and ovarian tumors as compared to the adjacent normal tissues and recognize sequence elements of the H-ras proto-oncogene

We examined the level of receptor binding in H-ras elements, using nuclear extracts derived from human endometrial and ovarian lesions and from adjacent normal tissue in gel retardation assays. We found increased binding of the glucocorticoid receptor (GR) to the H-ras GR element in more than 90% of endometrial tumors and in all ovarian tumors tested, as compared to the corresponding adjacent normal tissue. Additionally, we found elevated binding of the estrogen receptor (ER) in H-ras ER element in all pairs of ovarian tumor/normal tissue tested, whereas in ER-negative control breast tumor/normal tissue pairs, no differences in ER DNA-binding levels were observed. These results suggest that steroid hormone receptor binding could directly activate the H-ras oncogenic potency in human endometrial and ovarian lesions, providing additional evidence for the role of H-ras expression in hormonally responsive human cancers.     

A tomato stem cell extract, containing antioxidant compounds and metal chelating factors, protects skin cells from heavy metal-induced damages

Heavy metals can cause several genotoxic effects on cells, including oxidative stress, DNA sequence breakage and protein modification. Among the body organs, skin is certainly the most exposed to heavy metal stress and thus the most damaged by the toxic effects that these chemicals cause. Moreover, heavy metals, in particular nickel, can induce the over-expression of collagenases (enzymes responsible for collagen degradation), leading to weakening of the skin extracellular matrix. Plants have evolved sophisticated mechanisms to protect their cells from heavy metal toxicity, including the synthesis of metal chelating proteins and peptides, such as metallothioneins and phytochelatins (PC), which capture the metals and prevent the damages on the cellular structures. To protect human skin cells from heavy metal toxicity, we developed a new cosmetic active ingredient from Lycopersicon esculentum (tomato) cultured stem cells. This product, besides its high content of antioxidant compounds, contained PC, effective in the protection of skin cells towards heavy metal toxicity. We have demonstrated that this new product preserves nuclear DNA integrity from heavy metal damages, by inducing genes responsible for DNA repair and protection, and neutralizes the effect of heavy metals on collagen degradation, by inhibiting collagenase expression and inducing the synthesis of new collagen.     

Comparing computer-supported dynamic modeling and ‘paper & pencil’ concept mapping technique in students’ collaborative activity

This study aims at highlighting the collaborative activity of two high school students (age 14) in the cases of modeling the complex biological process of plant growth with two different tools: the ‘paper & pencil’ concept mapping technique and the computer-supported educational environment ‘ModelsCreator’. Students’ shared activity in both cases is carried out in the presence of a facilitator providing technical as well as cognitive support when necessary. The objective of the study is to highlight the ways in which the collaborating students are engaged in the plant growth modeling activity in the two cases and also identify the activity’s similar and different aspects in each one. Our analysis is carried out on two complementary axes, the first of which concerns the process of collaboratively creating a plant growth model with each different tool, while the second has to do with the students’ conceptualizations of the biological aspect of the modeling task in each case. A two-level analytic tool for the modeling process has been derived within the theoretical framework of ‘activity theory’ on the basis of the OCAF scheme for basic modeling operations and the scheme of Stratford et al. [Stratford, S. J., Krajcik, J., & Soloway, E. (1998). Secondary students’ dynamic modeling processes: analyzing, reasoning about, synthesizing, and testing models of stream ecosystems. Journal of Science Education and Technology, 7(3), 215–234.] for higher-order modeling actions. According to our results, four major modeling actions (analysis, synthesis, testing-interpreting, technical and cognitive support) performed through a plethora of modeling operations define the steps of the modeling process in both cases, while specific qualitative differences can be actually identified. Finally, the students’ conceptualizations of the biological aspect of the modeling task in the two-case activity is analyzed in regard with their capability of shifting reasoning between macro- and micro-levels, while educational implications are also discussed.     

Association of herpesvirus infection with the development of genital cancer

Clinical observations and epidemiological studies on genital cancer have revealed an association with sexual behavior, thus motivating research into sexually transmitted agents which may be responsible for the neoplasia. In this study, we used the PCR technique to examine the presence of CMV, HSV and EBV viruses in 187 cases of human genital lesions and found that infection with CMV or HSV was associated with cervical cancer. When we stratified according to HPV status this association was found only for HPV-DNA-negative cases. These findings indicate that past infection with CMV or HSV could be interpreted as a surrogate marker of HPV infection. However, these viruses may play an important role themselves in cervical cancer.     

Microsatellite instability in human atherosclerotic plaques

The aetiopathology of atherosclerosis remains obscure. Although histologically the accumulation of lipids and the proliferation of the smooth muscle cells represents the main feature of the disease, little is known as regards the molecular alterations associated with the atherosclerotic lesions. In the present study we investigated whether an elevated mutational rate is detectable in human atheromatous plaques. Thirty specimens were assessed for microsatellite instability (MI) by 7 microsatellite markers and MI, in at least one marker, was apparent in 6 (20%) cases. Our data suggest that decreased fidelity in DNA replication and repair may be associated with the development of the disease.