Nursing students' experiences of what influences achievement of learning outcomes in a problem-based learning context: A qualitative descriptive study.

AIM: This study aimed to describe nursing students' experiences of what facilitate or impede the achievement of learning outcomes in PBL-based nursing education. DESIGN: A qualitative descriptive design was used. METHODS: Data were collected from individual semi-structured interviews with 18 undergraduate nursing students in Sweden and were analysed using Burnard's qualitative content analysis. RESULTS: The results were organized into three categories: (a) understanding of the required level of knowledge depth (b) tutor's engagement and (c) student base group interactions. These categories represent essential components of PBL that could either facilitate or impede students' achievement of learning outcomes in nursing education. To improve the students' opportunities to achieve the learning outcomes, proper introduction of and a continuous education on PBL as a pedagogical method provided both to students and tutors should be considered important.

The Guinea-Bissau family of Mycobacterium tuberculosis complex revisited.

The Guinea-Bissau family of strains is a unique group of the Mycobacterium tuberculosis complex that, although genotypically closely related, phenotypically demonstrates considerable heterogeneity. We have investigated 414 M. tuberculosis complex strains collected in Guinea-Bissau between 1989 and 2008 in order to further characterize the Guinea-Bissau family of strains. To determine the strain lineages present in the study sample, binary outcomes of spoligotyping were compared with spoligotypes existing in the international database SITVIT2. The major circulating M. tuberculosis clades ranked in the following order: AFRI (n = 195, 47.10%), Latin-American-Mediterranean (LAM) (n = 75, 18.12%), ill-defined T clade (n = 53, 12.8%), Haarlem (n = 37, 8.85%), East-African-Indian (EAI) (n = 25, 6.04%), Unknown (n = 12, 2.87%), Beijing (n = 7, 1.68%), X clade (n = 4, 0.96%), Manu (n = 4, 0.97%), CAS (n = 2, 0.48%). Two strains of the LAM clade isolated in 2007 belonged to the Cameroon family (SIT61). All AFRI isolates except one belonged to the Guinea-Bissau family, i.e. they have an AFRI_1 spoligotype pattern, they have a distinct RFLP pattern with low numbers of IS6110 insertions, and they lack the regions of difference RD7, RD8, RD9 and RD10, RD701 and RD702. This profile classifies the Guinea-Bissau family, irrespective of phenotypic biovar, as part of the M. africanum West African 2 lineage, or the AFRI_1 sublineage according to the spoligtyping nomenclature. Guinea-Bissau family strains display a variation of biochemical traits classically used to differentiate M. tuberculosis from M. bovis. Yet, the differential expression of these biochemical traits was not related to any genes so far investigated (narGHJI and pncA). Guinea-Bissau has the highest prevalence of M. africanum recorded in the African continent, and the Guinea-Bissau family shows a high phylogeographical specificity for Western Africa, with Guinea-Bissau being the epicenter. Trends over time however indicate that this family of strains is waning in most parts of Western Africa, including Guinea-Bissau (p = 0.048).

Tumor selectivity at short times following systemic administration of a liposomal temoporfin formulation in a murine tumor model.

Meso-tetra(hydroxyphenyl)chlorin (mTHPC) (INN: Temoporfin) is one of the most potent photodynamically active substances in clinical use. Treatment protocols for Temoporfin-mediated photodynamic therapy often rely on drug-light intervals of several days in order for the photosensitizer to accumulate within the target tissue, though tumor selectivity is limited. Here, the mTHPC localization was studied at 2-8 h following systemic administration of a liposomal Temoporfin formulation (0.15 mg kg(-1) b.w.) in HT29 human colon adenocarcinoma in NMRI nu/nu mice. Photosensitizer distribution within tumor and internal organs was investigated by means of high performance liquid chromatography following chemical extraction, as well as in situ fluorescence imaging and point-monitoring fluorescence spectroscopy. For tumor tissue, the Temoporfin concentrations at 4 h (0.16+/-0.024 ng mg(-1)) and 8 h (0.18+/-0.064 ng mg(-1)) were significantly higher than at 2 h (0.08+/-0.026 ng mg(-1)). The average tumor-to-muscle and the tumor-to-skin selectivity were 6.6 and 2, respectively, and did not vary significantly with time after photosensitizer injection. In plasma, the Temoporfin concentration was low (0.07+/-0.07 ng mg(-1)) and showed no significant variation with time. Our results indicate a rapid biodistribution and clearance from the bloodstream. Within the same type of organ, data from both fluorescence methods generally exhibited a significant correlation with the extraction results.

Fluorescence monitoring of a topically applied liposomal Temoporfin formulation and photodynamic therapy of nonpigmented skin malignancies.

Meso-tetra(hydroxyphenyl)chlorin (mTHPC) (INN: Temoporfin) is a potent photodynamically active substance in clinical use today. Usually, the substance is given systemically and a known drawback with this administration route is a prolonged skin light sensitization. For the first time to our knowledge, a liposomal Temoporfin gel formulation for topical application was studied in connection with photodynamic therapy (PDT) of nonpigmented skin malignancies in humans. Intervals of 4 hr between drug administration and light irradiation were used. Sensitizer distribution within tumor and surrounding normal skin was investigated by means of point monitoring and imaging fluorescence spectroscopy before, during, and after PDT, showing high tumor selectivity. Furthermore, the bleaching of Temoporfin was studied during the PDT procedure by monitoring the fluorescence following excitation by using a therapeutic light. A 30-35% light-induced photometabolization was shown. No pain occurred during or after treatment. It was also observed that the treated area did not show any swollen tissue or reddening, as is often seen in PDT using topical delta-aminolevulinic acid. On controlling the patients one week after treatment, healing progress was observed in several patients and no complications were registered.

Fluorescence and absorption assessment of a lipid mTHPC formulation following topical application in a non-melanotic skin tumor model.

Although the benefits of topical sensitizer administration have been confirmed for photodynamic therapy (PDT), ALA-induced protoporphyrin IX is the only sensitizer clinically used with this administration route. Unfortunately, ALA-PDT results in poor treatment response for thicker lesions. Here, selectivity and depth distribution of the highly potent sensitizer meso-tetra(hydroxyphenyl)chlorin (mTHPC), supplied in a novel liposome formulation was investigated following topical administration for 4 and 6 h in a murine skin tumor model. Extraction data indicated an average [+/- standard deviation (SD)] mTHPC concentration within lesions of 6.0(+/-3.1) ngmg tissue with no significant difference (p<0.05) between 4- and 6-h application times and undetectable levels of generalized photosensitivity. Absorption spectroscopy and chemical extraction both indicated a significant selectivity between lesion and normal surrounding skin at 4 and 6 h, whereas the more sensitive fluorescence imaging setup revealed significant selectivity only for the 4-h application time. Absorption data showed a significant correlation with extraction, whereas the results from the fluorescence imaging setup did not correlate with the other methods. Our results indicate that this sensitizer formulation and administration path could be interesting for topical mTHPC-PDT, decreasing the effects of extended skin photosensitivity associated with systemic mTHPC administration.

Spatially varying regularization based on spectrally resolved fluorescence emission in fluorescence molecular tomography.

Fluorescence molecular tomography suffers from being mathematically ill-conditioned resulting in non-unique solutions to the reconstruction problem. In an attempt to reduce the number of possible solutions in the underdetermined system of equations in the reconstruction, we present a method to retrieve a spatially varying regularization map outlining the feasible inclusion position. This approach can be made very simple by including a few multispectral recordings from only one source position. The results retrieved through tissue phantom experiments imply that initial reconstructions with spatially varying priors reduces artifacts and show slightly more accurate reconstruction results compared to reconstructions using no priors.

Fluorescence spectra provide information on the depth of fluorescent lesions in tissue.

The fluorescence spectrum measured from a fluorophore in tissue is affected by the absorption and scattering properties of the tissue, as well as by the measurement geometry. We analyze this effect with Monte Carlo simulations and by measurements on phantoms. The spectral changes can be used to estimate the depth of a fluorescent lesion embedded in the tissue by measurement of the fluorescence signal in different wavelength bands. By taking the ratio between the signals at two wavelengths, we show that it is possible to determine the depth of the lesion. Simulations were performed and validated by measurements on a phantom in the wavelength range 815-930 nm. The depth of a fluorescing layer could be determined with 0.6-mm accuracy down to at least a depth of 10 mm. Monte Carlo simulations were also performed for different tissue types of various composition. The results indicate that depth estimation of a lesion should be possible with 2-3-mm accuracy, with no assumptions made about the optical properties, for a wide range of tissues.

Modeling of spectral changes for depth localization of fluorescent inclusion.

We have performed modeling of fluorescence signals from inclusions inside turbid media to investigate the influence of a limited fluorescence contrast and how accurately the depth can be determined by using the spectral information. The depth was determined by forming a ratio of simulated fluorescence intensities at two wavelengths. The results show that it is important to consider the background autofluorescence in determining the depth of a fluorescent inclusion. It is also necessary to know the optical properties of the tissue to obtain the depth. A 20% error in absorption or scattering coefficients yields an error in the determined depth of approximately 2-3 mm (relative error of 10-15%) in a 20 mm thick tissue slab.

Absorption across the nasal airway mucosa in house dust mite perennial allergic rhinitis.

House dust mite allergens express protease activity and it has been suggested that this property has pathogenic effects by increasing airway absorption. In accordance, house dust mite allergens may increase mucosal permeability in vitro. The objective of the present study was to examine nasal absorption of desmopressin (1-deamino-8-D-arginine vasopressin) in patients with perennial house dust mite allergic rhinitis and in healthy subjects in vivo. Patients with perennial allergic rhinitis were examined after a 4-week treatment withdrawal period, when symptoms of allergic rhinitis occurred, and healthy subjects were examined together with the patients. Desmopressin (20 microg ml(-1)) was moved into the nasal cavity using a nasal pool-device that contained 15 ml fluid. The fluid was kept in the nasal cavity for 15 min and then recovered. Urine was collected for 24 h after the nasal administration and the urinary excretion of desmopressin was determined as an index of nasal absorption. The urinary excretion of desmopressin was 1148+/-535 pmol 24 h(-1) in patients with perennial house dust mite allergic rhinitis and 1012+/-291 pmol 24 h(-1) in healthy subjects. We conclude that nasal airway absorption of the 1067 Da peptide desmopressin is unaffected in perennial house dust mite allergic rhinitis compared with healthy subjects.