Local variation in absolute water content of human and rabbit eye lenses measured by Raman microspectroscopy

Raman spectra were obtained from fresh, fixed and sliced rabbit lenses and from human lens slices. For all lenses and lens slices the ratio R, defined as the Raman intensity at 3390 cm−1 divided by the Raman intensity at 2935 cm−1, was measured at different locations along the visual and equatorial axis. The ratios R were transformed to absolute water mass percentages by measuring solutions with known protein concentrations. It was shown that fixation and slicing have very little effect on the absolute water content of the lenses. The values obtained for the absolute water content are comparable to values given in literature. It was also shown that the water content in rabbit and human lenses rapidly decreases from the immediate anterior and posterior subsurface region to the deep superficial cortex and is relatively constant in the nucleus. Raman microspectroscopy appears to be a reliable method for the measurement of the absolute water content of small volumes on defined positions in the lens. This can be very useful when analyzing the possible relation between local variations in water content and the occurrence of opacities in the lens

Assessment of significant variables to improve admission and teaching learning processes in a medical school.

Introduction: Current selection methods in medical schools emphasize academic competence only, somewhat to the detriment of other essential competencies. Academic grades are frequently considered as the predictors of good academic performance in medical schools and therefore many medical schools still select applicants predominantly on this basis. Objective: To assess this long-standing trend in order to point out the lacunae associated with it and to explore this effect with a view to improve teaching and learning process. Methodology: During this retrospective longitudinal study, we studied the students (n=539) admitted to the college of medicine, King Khalid University, Saudi Arabia, between 2006 and 2011. During these years study conditions (i.e. admission procedure, study program and assessment) remained unchanged. The scores of higher school certificate (HSC) were correlated with study duration (number of semesters) and grade point average (GPA). Pearson’s correlation and regression analysis were carried out using effect model. Results: The results of this study do not demonstrate a correlation between HSC scores and study duration (r = -.018). The relationship bet ween HSC scores and cumulative GPA was moderate positive (r = .476). The HSC scores were found to be poor predictors of the subsequent academic performance (R2 = .273). Conclusions: The HSC score is a poor predictor of the subsequent academic performance. Our intuition, and perhaps our experience, suggests that study time should be positively associated with grades. However, it is not always the case as study duration-grade association may not be true.   Keywords: School admission criteria, Medical education, Students, Undergraduate

Raman microspectroscopy of fixed rabbit and human lenses and lens slices: New potentialities

Raman spectroscopy is a non-invasive, non-destructive technique for the study of the macromolecular composition of tissues. Raman spectra were obtained from intact fresh and paraformaldehyde fixed rabbit lenses and from thin slices prepared from these lenses. In addition the Raman spectrum of an intact 82-yr-old human lens was compared with a slice of the same lens. It appeared that fixation with paraformaldehyde had only a minor qualitative effect on the Raman spectra and that Raman spectra of intact lenses and lens slices were comparable. It was also shown that in the slice of the old human lens the fluorescence, due to chromophores, could be reduced so that a reliable Raman spectrum could be obtained.\ud \ud The use of slices improves the accuracy of the position at which Raman spectra are recorded and fixation extends the time available for Raman analysis which is particularly important for the study of human lenses. Moreover, slicing enables Raman analysis of old human lenses, which up to now was thought to be impossible due to the overwhelming fluorescence of the chromophores present in these lenses

Influence of spinal cord stimulation on evoked potentials by cutaneous electrical stimulation

In the past, limited research has been done to investigate the influence of spinal cord stimulation (SCS) for treatment of chronic pain on evoked potentials (EP). Further insight into the mechanism of SCS may provide explanations for unsatisfactory results with this therapy in certain subpopulations. It also might predict effectiveness of SCS. In previous research MEG responses were measured on median and tibial nerve stimulations in chronic pain patients with and without SCS (1). However, this stimulation method preferentially activates large myelinated proprioceptive fibres, leaving painrelated small fibres unrelated. We expect that the observation of pain processing is impaired by large amounts of non-painrelated activity

Development of classical Hodgkin’s lymphoma in an adult with biallelic STXBP2 mutations

Experimental model systems have delineated an important role for cytotoxic lymphocytes in the immunosurveillance of cancer. In humans, perforin-deficiency has been associated with occurrence of hematologic malignancies. Here, we describe an Epstein-Barr virus-positive classical Hodgkin's lymphoma in a patient harboring biallelic mutations in STXBP2, a gene required for exocytosis of perforin-containing lytic granules and associated with familial hemophagocytic lymphohistocytosis. Cytotoxic T lymphocytes were found infiltrating the tumor, and a high frequency of Epstein-Barr virus-specific cytotoxic T lymphocytes were detected in peripheral blood. However, lytic granule exocytosis and cytotoxicity by cytotoxic T lymphocytes, as well as natural killer cells, were severely impaired in the patient. Thus, the data suggest a link between defective lymphocyte exocytosis and development of lymphoma in STXBP2-deficient patients. Therefore, with regards to treatment of familial hemophagocytic lymphohistocytosis patients with mutations in genes required for lymphocyte exocytosis, it is important to consider both the risks of hemophagocytic lymphohistocytosis and malignancy.Swedish Research CouncilSwedish Cancer FoundationSwedish Children’s Cancer FoundationHistiocytosis AssociationClas Groschinsky’s Memorial FundJeanssons FoundationÅke Olsson Foundation for Hematological ResearchÅke Wiberg FoundationKarolinska Institute Research FoundationStockholm County Council (ALF project)Publishe

Fractures in pituitary adenoma patients from the Dutch National Registry of Growth Hormone Treatment in Adults

Purpose: The effects of growth hormone (GH) replacement therapy on fracture risk in adult GH deficient (GHD) patients with different etiologies of pituitary GHD are not well known, due to limited data. The aim of this study was to investigate characteristics and fracture occurrence at start of (baseline) and during long-term GH replacement therapy in GHD adults previously treated for Cushing’s disease (CD) or acromegaly, compared to patients with previous nonfunctioning pituitary adenoma (NFPA). Methods: From the Dutch National Registry of Growth Hormone Treatment in Adults, a nationwide surveillance study in severe GHD adults, all patients using ≥30 days of GH replacement therapy with previous NFPA (n = 783), CD (n = 180) and acromegaly (n = 65) were selected. Patient characteristics, fractures and potential influencing factors were investigated. Results: At baseline, patients with previous CD were younger, more often female and had more often a history of osteopenia or osteoporosis, whereas patients with previous acromegaly had more often received cranial radiotherapy and a longer duration between treatment of their pituitary tumor and start of adult GH replacement therapy. During follow-up, a fracture occurred in 3.8 % (n = 39) of all patients. Compared to patients with previous NFPA, only patients with previous acromegaly had an increased fracture risk after 6 years of GH replacement therapy. Conclusions: During GH replacement therapy, an increased fracture risk was observed in severe GHD adult patients previously treated for acromegaly, but not in those previously treated for CD, compared to severe GHD adult patients using GH replacement therapy because of previous NFPA. Further studies are needed to confirm these findings and to elucidate potential underlying mechanisms

Co-occurrence based meta-analysis of scientific texts: retrieving biological relationships between genes

MOTIVATION: The advent of high-throughput experiments in molecular biology creates a need for methods to efficiently extract and use information for large numbers of genes. Recently, the associative concept space (ACS) has been developed for the representation of information extracted from biomedical literature. The ACS is a Euclidean space in which thesaurus concepts are positioned and the distances between concepts indicates their relatedness. The ACS uses co-occurrence of concepts as a source of information. In this paper we evaluate how well the system can retrieve functionally related genes and we compare its performance with a simple gene co-occurrence method. RESULTS: To assess the performance of the ACS we composed a test set of five groups of functionally related genes. With the ACS good scores were obtained for four of the five groups. When compared to the gene co-occurrence method, the ACS is capable of revealing more functional biological relations and can achieve results with less literature available per gene. Hierarchical clustering was performed on the ACS output, as a potential aid to users, and was found to provide useful clusters. Our results suggest that the algorithm can be of value for researchers studying large numbers of genes. AVAILABILITY: The ACS program is available upon request from the authors

Ambiguity of human gene symbols in LocusLink and MEDLINE: creating an inventory and a disambiguation test collection

Genes are discovered almost on a daily basis and new names have to be found. Although there are guidelines for gene nomenclature, the naming process is highly creative. Human genes are often named with a gene symbol and a longer, more descriptive term; the short form is very often an abbreviation of the long form. Abbreviations in biomedical language are highly ambiguous, i.e., one gene symbol often refers to more than one gene.Using an existing abbreviation expansion algorithm,we explore MEDLINE for the use of human gene symbols derived from LocusLink. It turns out that just over 40% of these symbols occur in MEDLINE, however, many of these occurrences are not related to genes. Along the process of making an inventory, a disambiguation test collection is constructed automatically

The clinical significance of androgen receptors in breast cancer and their relation to histological and cell biological parameters

To analyse the clinical significance of the presence of androgen receptors (AR) in breast carcinomas, clinical and histological parameters of 153 primary breast carcinomas (median follow-up 46 months) were examined. Oestrogen (ER) and progesterone receptor (PR) levels were determined in cytosol preparations using enzyme immunoassay assays and in cryostat sections by immunohistochemistry. AR and Ki-67 levels were only determined immunohistochemically. Data were analysed by uni- and multivariate models. 94/153 (61%) breast carcinomas were ER+ PR+ AR+, while 14 cases were only positive for AR. All grade III tumours (n = 17) were steroid receptor negative and 14 (76%) of these cases demonstrated high Ki-67 values suggestive of more aggressive behaviour. Strikingly, 14 ductal carcinomas negative for ER and PR were positive for AR. In univariate analysis, AR as well as ER, tumour size, lymph node status, grade and Ki-67 proved to be significant prognostic factors for disease free survival (DFS). Multivariate analysis, however, showed lymph node status, tumour size and ER status to be the only independent prognostic factors for DFS within this model. We conclude that simple histological and cell biological parameters, including AR, can be used to select high- and low-risk patients at the time of primary surgery and can provide valuable information on treatment options

Using contextual queries

Search engines generally treat search requests in isolation. The results for a given query are identical, independent of the user, or the context in which the user made the request. An approach is demonstrated that explores implicit contexts as obtained from a document the user is reading. The approach inserts into an original (web) document functionality to directly activate context driven queries that yield related articles obtained from various information sources