Collaboration on progress testing in medical schools in the Netherlands.

Progress testing in the Netherlands was originally developed at Maastricht University. Since the late 1990s, a collaboration has started between three medical schools to jointly produce and administer the progress test. Currently, the progress test is administered to five out of eight medical schools in the Netherlands. The collaboration has led to substantial decrease in necessary resources per participating school. Also, the data provide a rich source for comparisons between schools and can be instrumental in inducing improvements to the curricula. Logistics of large-scale administrations and possible differences of views on item quality could be seen as a disadvantage. Also, it is not always easy to fit the test in the local regulatory structure, because it is only partly owned by each individual school. Important lessons for us have been that the advantages of the collaboration clearly outweigh the disadvantages. Of course, good collegial communication is needed, but this is not enough: a legal binding agreement has to be drawn up. Most importantly, such a collaboration creates a critical mass to enable multi-centre research and development projects on progress testing.

Flexible electronic feedback using the virtues of progress testing.

The potential richness of the feedback for learners and teachers is one of the educational advantages of progress tests (PTs). Every test administration yields information on a student's knowledge level in each sub-domain of the test (cross-sectional information), and it adds a next point to the corresponding knowledge growth curve (longitudinal information). Traditional paper-based feedback has severe limitations and requires considerable effort from the learners to give meaning to the data. We reasoned that the PT data should be flexibly accessible in all pathways and with any available comparison data, according to the personal interest of the learner. For that purpose, a web-based tool (Progress test Feedback, the ProF system) was developed. This article presents the principles and features of the generated feedback and shows how it can be used. In addition to enhancement of the feedback, the ProF database of longitudinal PT-data also provides new opportunities for research on knowledge growth, and these are currently being explored.

Results of surgical repair of atrioventricular septal defect with double-orifice left atrioventricular valve.

OBJECTIVE: The outcome of surgical correction of atrioventricular septal defect with double-orifice left atrioventricular valve has improved in recent years but is still reported to be associated with high mortality and reoperation rates. Controversy exists about the management of the accessory orifice. We evaluated our results with correction of atrioventricular septal defect with double-orifice left atrioventricular valve. METHODS: Between 1975 and 2006, 21 patients underwent correction of atrioventricular septal defect with double-orifice left atrioventricular valve. Clinical data were obtained by means of retrospectively reviewing inpatient and outpatient medical records. To evaluate the influence of double-orifice left atrioventricular valve on mortality and the need for reoperation, a comparison was made with 291 consecutive patients who, during the same period, underwent correction of atrioventricular septal defect without double-orifice left atrioventricular valve. RESULTS: None of the 21 patients with double-orifice left atrioventricular valve had undergone a previous operation. The accessory orifice was managed with different techniques depending on the severity of the regurgitation. There was no in-hospital mortality, and there were 3 late deaths. Seven patients required 12 reoperations, 7 for left atrioventricular valve insufficiency. Double-orifice left atrioventricular valve had no influence on mortality but was a significant predictor for reoperation compared with repair of atrioventricular septal defect without double-orifice left atrioventricular valve. At the latest follow-up, all 18 survivors were in New York Heart Association functional class capital I, Ukrainian without medication. Only 1 patient showed residual mild left atrioventricular valve insufficiency. CONCLUSION: Atrioventricular septal defect with double-orifice left atrioventricular valve can be repaired with low mortality. However, double-orifice left atrioventricular valve is a predictor for reoperation. The accessory orifice is often competent and should then be left untouched. If regurgitation of the accessory orifice is present, this is best managed with suture or patch closure.

Chronic right ventricular pressure overload results in a hyperplastic rather than a hypertrophic myocardial response.

Myocardial hyperplasia is generally considered to occur only during fetal development. However, recent evidence suggests that this type of response may also be triggered by cardiac overload after birth. In congenital heart disease, loading conditions are frequently abnormal, thereby affecting ventricular function. We hypothesized that chronic right ventricular pressure overload imposed on neonatal hearts initiates a hyperplastic response in the right ventricular myocardium. To test this, young lambs (aged 2-3 weeks) underwent adjustable pulmonary artery banding to obtain peak right ventricular pressures equal to left ventricular pressures for 8 weeks. Transmural cardiac tissue samples from the right and left ventricles of five banded and five age-matched control animals were studied. We found that chronic right ventricular pressure overload resulted in a twofold increase in right-to-left ventricle wall thickness ratio. Morphometric right ventricular myocardial tissue analysis revealed no changes in tissue composition between the two groups; nor were right ventricular myocyte dimensions, relative number of binucleated myocytes, or myocardial DNA concentration significantly different from control values. In chronic pressure overloaded right ventricular myocardium, significantly (P < 0.01) more myocyte nuclei were positive for the proliferation marker proliferating cellular nuclear antigen than in control right ventricular myocardium. Chronic right ventricular pressure overload applied in neonatal sheep hearts results in a significant increase in right ventricular free wall thickness which is primarily the result of a hyperplastic myocardial response.

Development of the cardiac conduction system in atrioventricular septal defect in human trisomy 21.

In patients with atrioventricular septal defect (AVSD), the occurrence of nonsurgical AV block has been reported. We have looked for an explanation in the development of the AV conduction system. Human embryos with AVSD and trisomy 21 and normal embryos were examined (age 5-16 wk gestation). Antibodies to human natural killer cell-1 (HNK-1), muscle actin (HHF-35), and collagen VI were used to delineate the conduction system. As in normal hearts, HNK-1 transiently stains the AV conduction system, the sinoatrial node, and parts of the sinus venosus in AVSD. A large distance is present between the superior and inferior node-like part of the right AV ring bundle, comparable to 6-wk-old normal hearts. The definitive inferior AV node remains in dorsal position from 7 wk onward and does not appose to the superior node-like part as seen in normal hearts. Furthermore, in AVSD, a transient third HNK-1-positive "middle bundle" branch that is continuous with the retroaortic root branch and the superior node-like part can be identified, and thus the AV conduction system forms a figure-of-eight loop. At later stages, the AV node remains in dorsal position close to the coronary sinus ostium with a long nonbranching bundle that runs through thin fibrous tissue toward the ventricular septum. The formation of the AV node and the ventricular conduction system in AVSD and Down syndrome differs from normal development, which can be a causative factor in the development of AV conduction disturbances.

Long-term pulmonary sequelae in children who were treated with extracorporeal membrane oxygenation for neonatal respiratory failure.

OBJECTIVE: Extracorporeal membrane oxygenation (ECMO) is a life-saving therapy for neonates with intractable respiratory failure, but the long-term pulmonary outcome is unknown. Our aim was to investigate the long-term pulmonary sequelae of these children. STUDY DESIGN: We studied 50 children at 11.1 +/- 1.1 years (mean +/- SD) who had been treated with neonatal ECMO for meconium aspiration syndrome (38%), sepsis (18%), sepsis with pneumonia (12%), congenital diaphragmatic hernia (12%), congenital heart disease (8%), persistent pulmonary hypertension of the newborn (6%), and respiratory distress syndrome (4%) and 27 healthy controls (10.8 +/- 1.6 years). All subjects completed a respiratory questionnaire and performed pulmonary function and graded cardiopulmonary exercise testing. RESULTS: Neonatal ECMO survivors had hyperinflation (median residual volume: 131%), airway obstruction (median forced expired volume in 1 second: 79%), lower oxygen saturation with exercise, and lower peak oxygen consumption than controls. The ECMO group achieved similar exercise minute ventilation to controls, with more rapid and shallow breathing. ECMO survivors had an increased frequency of exercise-induced bronchospasm. Those who required higher inspired oxygen tension and ventilator pressures after weaning from ECMO had lower forced expired volume in 1 second and oxygen saturation values. CONCLUSION: Neonatal ECMO survivors experience lung injury lasting into later childhood. Lung dysfunction correlates with the extent and duration of barotrauma and oxygen exposure as neonates.

Preoperative polysomnograms and infant pulmonary function tests do not predict prolonged postoperative mechanical ventilation in children following scoliosis repair.

Our objective was the identification of children with scoliosis at higher risk of prolonged postoperative mechanical ventilation (MV) permits improved pre- and perioperative respiratory care to reduce postoperative complications. Pulmonary function testing (PFT) predicts prolonged postoperative MV in children who can reliably perform PFT, but some children cannot perform PFT. The objective of this study was to determine if polysomnography (PSG) or infant pulmonary function testing (IPFT) could predict prolonged postoperative MV (defined as MV >3 days) in children undergoing scoliosis surgery who could not reliably perform PFT. We studied 110 patients (age range, 10.8 +/- 4.9 [SD] years) who had preoperative PSG, and 18 patients (age range, 4.0 +/- 2.9 [SD] years) who had preoperative IPFT prior to undergoing any type of scoliosis repair by the Children's Hospital of Los Angeles Division of Orthopedic Surgery from January 1990- July 2001. The following information was reviewed and correlated: preoperative PSG parameters (baseline and nadir S(aO(2) ), baseline and peak P(ETCO(2) ), and apnea hypopnea index [AHI]), preoperative IPFT parameters (respiratory system compliance [C(rs)], respiratory system resistance [R(rs)], tidal volume [V(T)], and FRC), and length of postoperative MV. Twenty-seven patients (25%) who had PSG and 5 patients (28%) who had IPFT required postoperative MV >3 days. There was no association between baseline and nadir S(aO(2) )

Maximal expiratory flow at FRC (V'maxFRC): Methods of selection and differences in reported values.

We compared three methods of reporting maximal expiratory flow (V'maxFRC) measured in partial expiratory flow-volume curves (PEFVCs) at the point of functional residual capacity (FRC). PEFVCs were obtained with the rapid thoracoabdominal compression technique (RTC) on a total of 446 occasions in 281 HIV-negative, asymptomatic infants (4.8-28.1 months old). Three different expressions of V'maxFRC were recorded: 1) the highest measured flow (maxV'FRC), 2) the mean of the three highest flows (mean3V'FRC), and 3) the flow at FRC in a composite curve (compV'FRC) consisting of PEFVCs, obtained at different jacket pressures and superimposed at their distal limb. The numerical value of maxV'FRC was 7.4% (+/-5.6%) higher than the mean3V'FRC, and 11.9% (+/-17.7%) higher than the compV'FRC; the mean3V'FRC was 5% (+/-18.3%) higher than the compV'FRC. Bland-Altman analysis was used to evaluate the agreement between the three indices. The mean difference and 95% limits of agreement were: maxV'FRC -mean3V'FRC, 14 +/- 18 ml/sec; maxV'FRC - compV'(FRC), 23 +/- 58 ml/sec; and mean3V'(FRC) - compV'(FRC), 10 +/- 52 ml/sec. The differences between the slopes of the three indices (regressed against height) were statistically significant, although clinically unimportant. We conclude that despite their high correlation, the mean3V'FRC and maxV'FRC should not be used interchangeably, and that the composite analysis, although useful, does not improve the reproducibility of V'maxFRC, and thus it cannot be recommended for routine use in its current form.

The role of neural crest and epicardium-derived cells in conduction system formation.

During cardiac development the heart tube loops and is septated into a four-chambered structure. The initial peristaltic contraction of the primitive myocardium is replaced by a system of working myocardium and a myocardial-derived central and peripheral conduction system. The genes guiding this differentiation process are still under investigation and it has yet to be decided whether we are dealing with a recruitment or a specification model. We have shown that the complicated looping process of the heart tube brings together the essential parts of the sinoatrial and primary ring myocardium, that are the embryonic precursors of the definitive conduction system. From our studies it is evident that during development there are sinoatrial tracts that run between the sinoatrial and the atrioventricular node as well as tracts surrounding the pulmonary veins and the coronary sinus. Furthermore, we show that both in the chicken and mouse embryo neural crest cells reach the confinement of the central conduction system through the inflow and outflow tract. For the Purkinje system there is a close approximation with the epicardium-derived cells. We postulate that both extracardiac-derived cell types have an influence on the differentiation of the definitive conduction system.

Sorption and desorption behavior of organotin compounds in sediment-pore water systems.

Sediments contaminated with organotin compounds (OTs), in particular triorganotins (TOTs), are abundant in areas with high shipping activities. To assess the possible remobilization of these highly toxic compounds from such sediments, a profound understanding of their sorption/desorption behavior is necessary. In this work the extent and reversibility of sorption of OTs to sediments has been investigated using contaminated freshwater harbor sediments and two certified OT containing marine sediments. Experiments conducted with perdeuterated OTs showed that sorption of OTs to sediments is a fast and reversible process involving primarily particulate organic matter (POM) constituents as sorbents. The organic carbon-normalized sediment-water distribution ratios (DOC, expressed in L/kgOC) determined in the laboratory were consistent with in-situ DOCs obtained from OT concentrations measured in sediment and pore water samples from two dated sediment cores. For both butyl- and phenyltin compounds the log DOC values were in the range of 4.7-6.1, and the following sequence was observed: DOC (tri-OT) > or = DOC (di-OT) > or = DOC (mono-OT). However, the differences were much less pronounced than would have been expected for hydrophobic partitioning of the corresponding compounds into POM. These results support our hypothesis from earlier work with dissolved humic acids that OT sorption to sediments occurs primarily by reversible formation of (innerspere) complexes between the tin atom and carboxylate and phenolate ligands present in POM. Because of the high DOC values (i.e. log DOC > or = 4) the diffusion of OTs from deeper sediments to the surface will be rather slow, and thus a major release from undisturbed sediments is not expected. However, because OTs readily desorb, any resuspension of contaminated sediments (e.g., by the tide, storms or dredging activities) will lead to enhanced OT concentrations in the overlaying water column. Furthermore, in contrastto polycyclic aromatic hydrocarbons (PAH) where large fractions may be tightly bound (in)to soot or other carbonaceous materials, OTs will be more readily bioavailable due to the fast and reversible sorption/desorption behavior.

New concepts for nutrition education in an era of welfare reform.

In response to welfare reform and the Food Stamp Nutrition Education Program's (FSNEP) goal of increasing clients' self-sufficiency, a literature review and small exploratory study were conducted to gain insight into a potential approach that would go beyond current nutrition education methods. Interviews with 17 FSNEP participants showed a widespread willingness to share food-related skills that others wanted to learn, some interest in cooperating on food-related projects, and frequent cases of social and geographic isolation. Based on these preliminary findings, we suggest the development and evaluation of nutrition education programs that appreciate and build on existing abilities of participants, provide opportunities for self-directed learning and activities, and build social support, social networks, and trust among participants while linking them to the broader community.

Structural changes of mitochondria in Chlamydomonas reinhardii after chloramphenicol treatment.

Ultrastructural and morphological alterations of mitochondria in the phytoflagellate Chlamydomonas reinhardii have been studied by use of serial sections after treatment with chloramphenicol. Remarkable volume changes could be observed as well as alterations in the internal fine structure of mitochondria. Under certain conditions, megamitochondria are formed with volumes exceeding 1 mum3. The changes, probably due to inhibition of mitochondrial protein synthesis, are described in some detail.

Comparative electrophoretic study on ribosomal proteins from algae.

The proteins from cytoplasmic ribosomal subunits of eight species of algae were analyzed by two-dimensional gel electrophoresis. The molecular weights of the proteins were in the range of 10,000 to 55,000. We have compared the protein patterns from the ribosomal subunits of the different species to those of Chlamydomonas reinhardii. It was quite clear that there are many similarities in the protein patterns of all the investigated species. We found for Chlamydomonas eugametos 48, Chlamydomonas noctigama 42, Chlorogonium elongatum 47, Scenedesmus obliquus 40, Chlorella fusca 35, and Euglena gracilis 35 proteins which were homologous to those of Chlamydomonas reinhardii. For the colorless flagellate Polytoma papillatum, we detected 45 proteins homologous to Chlamydomonas reinhardii, so that the generally assumed close relationship between Chlamydomonas and Polytoma is confirmed.

Variability of mitochondrial population in Chlamydomonas reinhardii.

Several details have been published cocerning the mitochondrial number and shapes at various stages of the synchronized vegetative and generative cell cycle in Chlamydomonas reinhardii. The present study, based on ultrathin serial sections and threedimensional reconstructions, completes these data. Quantitative analysis of serial micrographs makes it possible to give specific details of mitochondrial volumes in cells at early intermediate stages of the vegetative life cycle. Our investigations clearly show that mitochondria have a relatively wide range of sizes, within certain limits, and vary like the mitochondrial shapes; in fact, they vary in various cells at various stages as well as in several cells at the same stage and even in one and the same cell. Thus, we present a plastic insight into the dynamically changing micromorphology of the mitochondrial population in Chlamydomonas reinhardii.

Time-sequence of nuclear and chloroplast fusions in the zygote of Chlamydomonas reinhardii.

Contradictory data have been published concerning the time-sequence of nuclear and chloroplast fusions in the zygote of Chlamydomonas. In the present study, adjacent ultrathin sections of Chlamydomonas reinhardii zygotes of various ages were examined with the electron microscope. These sections clearly reveal that nuclear fusion precedes chloroplast fusion.

[Effects of gentamicin and lincomycin on the ultrastructure of mitochondria and plastids of Chlamydomonas reinhardii (author's transl)]. / Die Wirkung von Gentamycin und Lincomycin auf die Ultrastruktur der Mitochondrien und Plastiden von Chlamydomonas reinhardii.

It is known that antibiotics which have an effect on 70 S ribosomes inhibit both the bacterial and the mitochondrial protein synthesis of plants and animals. This also applies to the plastid protein synthesis of plants. On this basis the present study has examined whether the inhibition of the mitochondrial protein synthesis caused by such antibiotics, may also be recognized by structural changes in the mitochondria. The effects on the ultrastructure of plastids have been investigated comparatively. The mixotroph flagellate Chlamydomonas reinhardii was used in our study. It was found that gentamycin (0.3 to 0.6 microgram/ml) and lincomycin (200 and 300 microgram/ml) cause structural anomalies in the mitochondria and in the plastids as well. Depending on the concentrations and the periods of exposure the mitochondria exhibited the following alterations: disorientation of the cristae within the organelles, reduction in the number of cristae and considerable differences of their length. In addition, vesicles and bodies which are surrounded by circular single or doubled membranes appeared in the mitochondria under the influence of gentamycin. We were able to detect mitochondria of unusual sizes and shapes in the cross sections. We also noticed changes in the arrangement of the thylakoids in the plastids under the influence of both gentamycin and lincomycin. In addition, electron-dense thylakoids, the so-called compact membranes, appeared under the influence of gentamycin. We suspect that mitochondrial alterations under the influence of such antibiotics could be one of the causes of side-effects, which frequently occur in medical use.