Teaching a difficult topic using a problem-based concept resembling a computer game: development and evaluation of an e-learning application for medical molecular genetics.

BACKGROUND: Genetic testing rapidly penetrates into all medical specialties and medical students must acquire skills in this area. However, many of them consider it difficult. Furthermore, many find these topics less appealing and not connected to their future specialization in different fields of clinical medicine. Student-centred strategies such as problem-based learning, gamification and the use of real data can increase the appeal of a difficult topic such as genetic testing, a field at the crossroads of genetics, molecular biology and bioinformatics. METHODS: We designed an electronic teaching application which students registered in the undergraduate Medical Biology course can access online. A study was carried out to assess the influence of implementation of the new method. We performed pretest/posttest evaluation and analyzed the results using the sign test with median values. We also collected students' personal comments. RESULTS: The newly developed interactive application simulates the process of molecular genetic diagnostics of a hereditary disorder in a family. Thirteen tasks guide students through clinical and laboratory steps needed to reach the final diagnosis. Genetics and genomics are fields strongly dependent on electronic databases and computer-based data analysis tools. The tasks employ publicly available internet bioinformatic resources used routinely in medical genetics departments worldwide. Authenticity is assured by the use of modified and de-identified clinical and laboratory data from real families analyzed in our previous research projects. Each task contains links to databases and data processing tools needed to solve the task, and an answer box. If the entered answer is correct, the system allows the user to proceed to the next task. The solving of consecutive tasks arranged into a single narrative resembles a computer game, making the concept appealing. There was a statistically significant improvement of knowledge and skills after the practical class, and most comments on the application were positive. A demo version is available at https://medbio.lf2.cuni.cz/demo_m/ . Full version is available on request from the authors. CONCLUSIONS: Our concept proved to be appealing to the students and effective in teaching medical molecular genetics. It can be modified for training in the use of electronic information resources in other medical specialties.

Simplified stratum corneum model membranes for studying the effects of permeation enhancers.

The activity of transdermal permeation enhancers is usually evaluated in vitro on human or animal skin, but skin samples can be hard to source and highly variable. To provide a more consistent basis for evaluating the activity of permeation enhancers, we prepared relatively simple and inexpensive artificial membranes that imitate the stratum corneum (SC) lipid matrix. Our membranes were composed of stearic acid, cholesterol, cholesterol sulfate and a ceramide (CER) component consisting of N-2-hydroxystearoyl phytosphingosine (CER[AP]) and/or N-stearoyl phytosphingosine (CER[NP]). First, the permeation of theophylline (TH) and indomethacin (IND) through these membranes was compared with their permeation through porcine skin. Because the mixed CER[AP]/[NP] membrane gave the closest results to skin, this membrane was then used to test the effects of two permeation enhancers: N-dodecyl azepan-2-one (Azone) and (S)-N-acetylproline dodecyl ester (L-Pro2). Both enhancers significantly increased the flux of TH and IND through the skin and, even more markedly, through the lipid membrane, L-Pro2 having a stronger effect than Azone. Thus, our simplified model of the SC lipid membrane based on phytosphingosine CERs appears to be suitable for mimicking skin permeation.

Physical Compatibility of Propofol-Sufentanil Mixtures.

BACKGROUND: Combined infusions of propofol and sufentanil preparations are frequently used in clinical practice to induce anesthesia and analgesia. However, the stability of propofol emulsions can be affected by dilution with another preparation, sometimes leading to particle coalescence and enlargement. Such unwanted effects can lead to fat embolism syndrome after intravenous application. This study describes the physical stability of 5 commercially available propofol preparations mixed with sufentanil citrate solutions. METHODS: Two common markers of emulsion stability were used in this study; namely, the zeta potential and size distribution of the emulsion droplets. Both were measured using dynamic light scattering. The data for the pure propofol preparations and their mixtures with sufentanil citrate solution were compared. RESULTS: The absolute value of zeta potential decreased in 4 of the 5 propofol preparations after they had been mixed with sufentanil citrate. This effect indicates a lowering of repulsive interactions between the emulsion droplets. Although this phenomenon tends to cause agglomeration, none of the studied mixtures displayed a substantial increase in droplet size within 24 hours of blending. However, our long-term stability study revealed the instability of some of the propofol-sufentanil samples. Two of the 5 studied mixtures displayed a continual increase in particle size. The same 2 preparations showed the greatest reductions in the absolute value of zeta potential, thereby confirming the correlation of both measurement methods. The increase in particle size was more distinct in the samples stored at higher temperatures and with higher sufentanil concentrations. CONCLUSIONS: To ensure the microbial stability of an emulsion infusion preparation, clinical regulations require that such preparations should be applied to patients within 12 hours of opening. In this respect, we can confirm that during this period, none of the studied propofol-sufentanil mixtures displayed any physical instability that could lead to particle enlargement; thus, fat embolism should not be a risk after their intravenous application. However, our long-term stability study revealed differences between commercially available preparations containing the same active ingredient; some of the mixtures showed an increase in particle size and polydispersity over a longer period. Although our results should not be generalized beyond the particular propofol-sufentanil preparations and concentrations studied here, they do suggest that, as a general principle, a compatibility study should be performed for any preparation before the first intravenous application to exclude the risk of droplet aggregation.

The TP53 gene promoter is not methylated in families suggestive of Li-Fraumeni syndrome with no germline TP53 mutations.

Germline TP53 mutations are found in only 70% of families with the Li-Fraumeni syndrome (LFS), and with an even lower frequency in families suggestive of LFS but not meeting clinical criteria of the syndrome. Despite intense efforts, to date, no other genes have been associated with the disorder in a significant number of TP53 mutation-negative families. A search for defects in TP53 other than heterozygous missense mutations showed that neither intron variants nor sequence variants in the TP53 promoter are frequent in LFS, and multiexon deletions have been found to be responsible for LFS only in several cases. Another cancer predisposition syndrome, hereditary non-polyposis colon cancer, has been associated with epigenetic silencing of one allele of the MLH1 or MSH2 genes. This prompted us to test the methylation of the TP53 gene promoter in a set of 14 families suggestive of LFS using bisulphite sequencing of three DNA fragments from the 5' region of the gene. We found no detectable methylation at any of the CG dinucleotides tested. Thus, epigenetic silencing of the TP53 promoter is not a frequent cause of the disorder in families suggestive of LFS but with no germline mutations in the coding part of the gene.

Somatic TP53 mutation mosaicism in a patient with Li-Fraumeni syndrome.

We present a girl who developed adrenocortical adenoma at the age of 1 year and osteosarcoma at the age of 5 years. There was no history of cancer in her parents and their relatives. However, both tumors were typical for the Li-Fraumeni syndrome (LFS), and the patient met criteria for germline TP53 mutation testing. A mutation in codon 282 (Arg282Trp) was identified in her blood lymphocyte genomic DNA. The substitution was found in neither of her parents, which indicated a possibility of a de novo mutation. Unexpectedly, sequencing of the DNA of the patient repeatedly showed allelic imbalance in favor of the normal allele. This observation prompted us to investigate the putative somatic mosaicism in the patient consisting of normal cells and cells heterozygous for the mutation. The imbalance was also examined in two other non-invasively sampled tissues, buccal cells, and cells from the urine sediment, and sequencing was confirmed with two other independent methods. While the findings in blood and the urine sediment were similar, in buccal cells both alleles were present in equal amounts. The allele ratio in lymphocytes was consistent with a mosaic where about 2/3 of cells carried two normal alleles and only 1/3 was heterozygous for the mutation. Despite the mosaicism the girl developed two early childhood tumors of mesodermal origin, and her phenotype was thus not milder than that of other germline TP53 mutation carriers. To our knowledge this is the first description of somatic mosaicism for a de novo TP53 mutation in LFS.

A rare tumor and an ethical dilemma in a family with a germline TP53 mutation.

We describe a family with a history of cancer suggestive of the Li-Fraumeni syndrome (LFS). A 27-year-old woman suffered at 17 years of age from phyllodes breast tumor and was shown to carry a germline mutation in the TP53 gene. Two years after testing, she became pregnant and was offered prenatal diagnosis by her gynecologist. The patient expressed her commitment to deliver the baby regardless of its mutation status, but with a strong interest in having the child tested soon after the birth. When she was informed that testing of children is usually postponed until after they reach 18 years of age, she consulted several geneticists, who repeatedly discouraged her from the intent to test the newborn. In the end, the patient decided for prenatal genetic testing only to learn the mutation status of the child. This scenario being unacceptable, she was offered early postnatal testing of the child, and this analysis showed that the newborn boy carried the mutation. Based on this finding, the family was enrolled into a preventive screening program for childhood cancer. The case illustrates ethical problems associated with early predisposition testing in LFS, and the lack of consensus on this issue in the literature.

Telomere length in peripheral blood cells of germline TP53 mutation carriers is shorter than that of normal individuals of corresponding age.

BACKGROUND: A decrease in the age at cancer onset and increase in cancer incidence in successive generations in Li-Fraumeni syndrome (LFS) families with germline TP53 mutations have been previously described. In the current study a possible relation was analyzed between telomere length and cancer onset in TP53 mutation carriers. METHODS: Telomere length was measured using real-time quantitative polymerase chain reaction (PCR) in 20 carriers of germline TP53 mutations and in 83 unrelated healthy individuals. According to the age at blood sampling, patients and controls were divided into 2 age groups, children and adults. Telomere length was correlated to TP53 mutation status and telomere shortening in patients to the age at cancer onset. A t-test and linear regression were used to analyze the data. RESULTS: Compared with healthy controls, telomere length was significantly shorter both in the child (P = .001) and adult (P = .034) germline T53 mutation carriers. Although a statistically significant correlation between telomere shortening and the age at cancer onset was not observed, there was a trend of shorter telomeres in mutation carriers affected in childhood compared with those affected later in life. Neither cancer therapy nor sex differences were likely to affect the results. CONCLUSIONS: The findings suggest a possible link between the carriership of a germline TP53 mutation, telomere length, predisposition to early-onset cancer, and anticipation in LFS.