CBCT uses in clinical endodontics: the effect of CBCT on the ability to locate MB2 canals in maxillary molars.

AIM: To determine whether a CBCT volume can aid in the location of MB2 canals in maxillary molars. METHODOLOGY: This prospective clinical study involved 50 patients that needed RCT on a maxillary molar. The teeth where the MB2 was located upon access with the dental operating microscope received routine root canal treatment, and teeth where MB2 was not located had a CBCT volume made after instrumenting the located canals. At the second appointment, the clinician used the aid of the CBCT volume and troughing to attempt to locate MB2. RESULTS: The clinicians located MB2 upon initial access in 70% (n = 35) of teeth. In the remaining 15 teeth, CBCT and troughing located MB2 53% of the time in that group (8/15 teeth). Overall, MB2 was located in 86% of the 50 first and second maxillary molars (maxillary first molars 90% and maxillary second molars 73%). A total of 15 CBCT volumes were made, and of these teeth, 33% of MB2 canals (5/15 teeth) were visualized on the CBCT volume. CONCLUSIONS: This prospective clinical study showed that the effectiveness of using CBCT to locate additional MB2 canals in maxillary molars appears limited. The use of the dental operating microscope in conjunction with selective troughing and CBCT imaging allowed clinicians to locate 90% (maxillary first molars) and 73% (maxillary second molars) of MB2 canals.

Technical Note: A simple FTA® based method for the direct STR amplification of human foetal tissues.

Short tandem repeats (STRs) or microsatellites are short, tandemly repeated DNA sequences that involve a repetitive unit of 1-6 bp. DNA isolation and purification from a large number and often compromised samples gives problems to forensic labs for STR typing. Many of the conventional methods used in the isolation and purification of DNA from forensic samples are time consuming, expensive, hazardous for health and are often associated with greater risks of cross contamination. FTA® technology is a method designed to simplify the collection, shipment, archiving and purification of nucleic acid from a wide variety of biological samples. We report a new method for the direct STR amplification which can amplify STR loci from human foetal tissues spotted on FTA cards, bye-passing the need of DNA purification. The STR loci amplified by this method was compared with conventional method of STR profiling and was found absolutely matching. Therefore, this new method is demonstrated to be very useful for fast, less expensive and non- hazardous forensic DNA analysis.

Is camouflaging unique for autism? A comparison of camouflaging between adults with autism and ADHD.

Camouflaging (using (un)conscious strategies to appear as non-autistic) is thought to be an important reason for late autism diagnoses and mental health difficulties. However, it is unclear whether only autistic people camouflage or whether people with other neurodevelopmental or mental health conditions also use similar camouflaging strategies. Therefore, in this preregistered study (AsPredicted: #41811) study, we investigated if adults with attention-deficit/hyperactivity-disorder (ADHD) also camouflage. Adults aged 30-90 years filled in the Dutch Camouflaging Autistic Traits Questionnaire (CAT-Q-NL), the ADHD Self-Report (ADHD-SR) and the Autism Spectrum Quotient (AQ). We investigated differences in camouflaging between adults with ADHD, autism, and a comparison group in an age and sex-matched subsample (N = 105 per group). We explored if autism and ADHD traits explained camouflaging levels in adults with an autism and/or ADHD diagnosis (N = 477). Adults with ADHD scored higher on total camouflaging and assimilation subscale compared to the comparison group. However, adults with ADHD scored lower on total camouflaging, and subscales compensation and assimilation than autistic adults. Autism traits, but not ADHD traits, were a significant predictor of camouflaging, independent of diagnosis. Thus, camouflaging does not seem to be unique to autistic adults, since adults with ADHD also show camouflaging behavior, even though not as much as autistic adults. However, as the CAT-Q-NL specifically measures camouflaging of autistic traits it is important to develop more general measures of camouflaging, to compare camouflaging more reliably in people with different mental health conditions. Furthermore, focusing on camouflaging in adults with ADHD, including potential consequences for late diagnoses and mental health seems a promising future research avenue.

Neutropenic enterocolitis after high-dose chemotherapy and autologous stem cell transplantation: incidence, risk factors, and outcome.

BACKGROUND: Neutropenic enterocolitis (NE) is a life-threatening complication occurring after intensive chemotherapy; however, no data are available on NE development after hematopoietic stem cell transplantation (SCT). The aim of this study was to determine the incidence, risk factors, and outcome of NE after high-dose chemotherapy and autologous SCT (autoSCT). METHODS: A total of 297 adult patients who qualified for autoSCT with non-Hodgkin's lymphoma (NHL), Hodgkin's disease, multiple myeloma, and acute myeloid leukemia were analyzed. Patients were conditioned with carmustine, etoposide, cytarabine, melphalan (BEAM); melphalan alone; or busulfan and cyclophosphamide (BuCy2), and transplanted with peripheral blood or bone marrow CD34(+) cells. Diagnosis of NE was established in case of neutropenic fever, abdominal pain or diarrhea, and bowel wall thickening >4 mm on abdominal sonography. RESULTS: Neutropenic infections occurred in 262 patients (88%). NE was diagnosed in 32 patients (12%), a median +3 (1-5) days after SCT. Bloodstream infections were present in 18 patients, with gram-negative bacteria in 11 patients. All patients were treated conservatively with carbapenems and total parenteral nutrition with bowel rest. The course of disease was complicated by ileus or septic shock in 9 patients, and was fatal for 3 (9.6%) patients. In univariate analysis, the initial diagnosis of NHL (P = 0.017) and conditioning with BEAM (P = 0.043) had prognostic value. In multivariate analysis, only initial diagnosis of NHL (P = 0.017) had prognostic significance. CONCLUSIONS: NE is a rare but severe complication in patients undergoing autoSCT. Gram-negative bacteria remain the main causative pathogen. Abdominal sonography allows early diagnosis and treatment, effective in most of patients without surgery. In our analysis, NE was seen more often in NHL patients treated with a BEAM regimen.

A comparative analysis of the collagen architecture in the carotid artery: second harmonic generation versus diffusion tensor imaging.

Collagen is the main load-bearing component of the artery. The 3D arrangement of the collagen fibers is crucial to understand the mechanical behavior of such tissues. We compared collagen fiber alignment obtained by second harmonic generation (SHG) microscopy with the alignment obtained by diffusion tensor imaging (DTI) throughout the wall of a porcine carotid artery to check the feasibility of using DTI as a fast and non-destructive method instead of SHG. The middle part of the artery was cut into two segments: one for DTI and one for the SHG measurements. The tissue for SHG measurements was cut into 30µm tangential sections. After scanning all sections, they were registered together and the fiber orientation was quantified by an in-house algorithm. The tissue for DTI measurement was embedded in type VII agarose and scanned with an MRI-scanner. Fiber tractography was performed on the DTI images. Both methods showed a layered structure of the wall. The fibers were mainly oriented circumferentially in the outer adventitia and media. DTI revealed the predominant layers of the arterial wall. This study showed the feasibility of using DTI for evaluating the collagen orientation in native artery as a fast and non-destructive method.

Disturbed cerebral circulation during opening of the venoarterial bypass bridge in extracorporeal membrane oxygenation.

PURPOSE: To describe the effects on cerebral blood flow velocity (CBFV) of intermittent opening of the venoarterial bridge (VA bridge) during venoarterial extracorporeal membrane oxygenation (VA-ECMO). STUDY DESIGN: Prospective study in 22 newborns during VA ECMO. CBFV was measured in the pericallosal artery by Doppler ultrasound. Changes in peak systolic flow velocity (PSV), end diastolic flow velocity (EDV) and time-averaged mean flow velocity (TAM) on day 1, 2, 3, and 5 and at low ECMO flow (50- 150 ml/min) were analyzed (mean percentage+/-standard deviation (t-tests, p<0.05)). Changes >25% were considered relevant. The relationship between changes in CBFV and ECMO flow rate (Pearson correlation, p<0.01) was studied. RESULTS: Opening of the VA bridge resulted in statistically significant and relevant decreases in PSV (35 +/- 18%), EDV (93 +/- 15%) and TAM (68 +/- 13%), persisting during the consecutive days of treatment. Smaller changes in CBFV at low ECMO flow were statistically significant and mostly relevant: PSV (15 +/- 7%), EDV (76 +/- 21%) and TAM (40 +/- 12%). Changes in CBFV were positively correlated to the ECMO flow. CONCLUSION: Use of the VA bridge results in significant and relevant ECMO flow-dependent changes in CBFV, persisting during the treatment. The VA bridge should be used in such a way as to allow regular unclamping to be omitted.

Major sacrococcygeal teratoma in an extreme premature infant: a multidisciplinary approach.

Antenatally diagnosed, large sacrococcygeal teratomas in very premature infants are associated with a very poor outcome. We present an extreme premature infant with cardiac decompensation, diagnosed at 27 weeks and 1 day of gestational age. A positive outcome could be achieved with intensive multidisciplinary planning of the delivery, postnatal stabilization and surgical resection, as demonstrated in this case report.

[A right-sided congenital diaphragmatic hernia masked by pneumonia]. / Een rechtszijdige congenitale hernia diaphragmatica gemaskeerd door een pneumonie.

A 1-day-old premature newborn (34 weeks and 6 days) presented with respiratory insufficiency due to a group B haemolytic streptococcal (GBS) pneumonia. She recovered after temporary treatment with mechanical ventilation and antibiotics. At the time of discharge there was a slight increased fogging on the right side of the chest X-ray, interpreted as residual pleural effusion. Three days later the patient was readmitted with respiratory failure and a need for respiratory support. A chest CT scan revealed a right-sided congenital diaphragmatic hernia (CDH) with a large part of the liver and intestine in the chest. The diaphragmatic defect was closed during a surgical procedure. After an uneventful recovery the patient was discharged in good clinical condition. The combination of delayed presentation of right-sided CDH and neonatal GBS infection occurs rarely but has been described. Its pathogenesis is still unclear.

[Evidence isn't enough: some comments from the daily practice of acute psychiatry]. / 'Evidence' is niet genoeg; kanttekeningen uit de praktijk van de acute psychiatrie.

Randomised clinical trials (RCTs) generate knowledge that is useful in some situations but is of limited value when it comes to dealing with complex problems in clinical practice. By means of arguments drawn from acute psychiatry it is argued in this paper that a) the preconditions under which an intervention seems to work in a trial are all too often not met in the clinic; b) the problems that evidence-based interventions seek to solve tend to be unlike the problems that clinicians encounter in a day-to-day basis; and c) it is often impossible to ascertain the parameters against which the efficacy of intervention can be measured. Therefore, acute psychiatry, like all the other branches of healthcare, urgently needs not only information about 'proven efficacy' via RCTs but also other kinds of information derived from other methods of research.

Accuracy of Le Fort I osteotomy in bimaxillary splint-based orthognathic surgery: focus on posterior maxillary movements.

This retrospective study was performed to verify the accuracy of horizontal and vertical repositioning of the maxilla in bimaxillary osteotomy with a focus on posterior vertical displacement. Data from 39 orthognathic patients undergoing bimaxillary surgery including a one-piece Le Fort I osteotomy with pitch rotation and advancement at the University Hospitals of Leuven (Belgium), between January 2015 and April 2016, were included in the study. Preoperative and 1-week postoperative lateral cephalograms were digitized and imported into cephalometric software. Horizontal and vertical measurements of dental landmarks were used to assess the accuracy of maxillary repositioning, and errors were reported in terms of the mean and absolute mean. The horizontal advancements were randomly under- and over-corrected an average of 1.4mm±1.2mm. Vertical repositioning of the anterior maxilla followed the planning. A tendency for under-correction was found for posterior vertical intrusion of the maxilla. The same tendency towards under-correction of posterior maxillary inferior repositioning was detected when planned movements were greater than 3mm. For all studied groups, no significant difference was found between the planning and the results achieved, validating the use of intermediate splints.

Modulation of macrophage phenotype and protein secretion via heparin-IL-4 functionalized supramolecular elastomers.

Hallmark of the in situ tissue engineering approach is the use of bioresorbable, synthetic, acellular scaffolds, which are designed to modulate the inflammatory response and actively trigger tissue regeneration by the body itself at the site of implantation. Much research is devoted to the design of synthetic materials modulating the polarization of macrophages, which are essential mediators of the early stages of the inflammatory response. Here, we present a novel method for the functionalization of elastomers based on synthetic peptide chemistry, supramolecular self-assembly, and immobilization of heparin and interleukin 4 (IL-4), which is known to skew the polarization of macrophages into the wound healing "M2" phenotype. Ureido-pyrimidinone (UPy)-modified chain extended polycaprolactone (CE-UPy-PCL) was mixed with a UPy-modified heparin binding peptide (UPy-HBP) to allow for immobilization of heparin, and further functionalization with IL-4 via its heparin binding domain. As a first proof of principle, CE-UPy-PCL and UPy-HBP were premixed in solution, dropcast and exposed to primary human monocyte-derived macrophages, in the presence or absence of IL-4-heparin functionalization. It was demonstrated that the supramolecular IL-4-heparin functionalization effectively promoted macrophage polarization into an anti-inflammatory phenotype, in terms of morphology, immunohistochemistry and cytokine secretion. Moreover, the supramolecular functionalization approach used was successfully translated to 3D electrospun scaffolds for in situ tissue engineering purposes, where UPy-HBP retention, and heparin and IL-4 attachment to the supramolecular scaffolds were proven over 7 days. Lastly, human monocyte-derived macrophages were cultured on 3D scaffolds, which, in case of IL-4-heparin functionalization, were proven to promote of an anti-inflammatory environment on protein level. This study presents a novel method in designing a versatile class of functionalized elastomers that effectively harness the anti-inflammatory behavior of macrophages in vitro, and as such, may be instrumental for the development of a new class of synthetic materials for in situ tissue engineering purposes. STATEMENT OF SIGNIFICANCE: Macrophages and their phenotypic and functional plasticity play a pivotal role in metabolic homeostasis and tissue repair. Based on this notion, bioactivated materials modulating macrophage polarization were extensively investigated in the past. Here, we designed immunomodulating, synthetic materials based on supramolecular immobilization of a heparin binding peptide, and further bioactivation with heparin and IL-4, an anti-inflammatory cytokine responsible for M2 activation and polarization. Human monocyte-derived macrophages cultured on heparin-IL-4 bioactivated materials displayed an elongated morphology and an anti-inflammatory phenotype, with downregulation of pro-inflammatory cytokines and promotion of anti-inflammatory cytokines over time. This study represents the first step in designing a novel class of synthetic, bioactivated materials that harness the regenerative behavior of host macrophages towards in situ tissue regeneration.

New experimental markers for early detection of high-risk prostate cancer: role of cell-cell adhesion and cell migration.

Today's treatment and diagnosis of prostate cancer still exhibit major limitations. The search for new and additional prognostic markers is therefore still an actual field of interest. Potential markers involved in numerous biological processes in the tumor cell have been investigated intensively. For therapeutic interventions it is important to distinguish between harmless and aggressive disease in an early stage. Therefore the subject of this review is limited to markers associated with those functional processes, which discriminate early stage aggressive, metastatic cancer from harmless disease. Important processes in this respect are: altered cell adhesion and cellular migration. E-cadherin, N-cadherin, beta-catenin, integrins, focal adhesion kinase, connexins and matrix metalloproteinases all appear promising biological markers associated with the early stage metastatic process in prostate cancer. Here we discuss their potential to become valid biological markers based on literature data. Thus far, none of these markers proved to be a valid individual marker by itself due to prostate cancer heterogeneity and transient expression. Analyzing a combination of the potential markers discussed in this review is expected to be a better approach toward discriminating high- from low-risk tumors in an early stage of prostate cancer.

The absence of benzodiazepine craving in a general practice benzodiazepine discontinuation trial.

This study aimed to assess benzodiazepine craving longitudinally and to describe its time course by means of the Benzodiazepine Craving Questionnaire (BCQ). Subjects were long-term benzodiazepine users participating in a two-part treatment intervention aimed to reduce long-term benzodiazepine use in general practice in The Netherlands. Four repeated measurements of benzodiazepine craving were taken over a 21-month follow-up period. Results indicated that (1) benzodiazepine craving severity decreased over time, (2) patients still using benzodiazepines experienced significantly more severe craving than patients who had quit their use after one of the two interventions, and (3) the way in which patients had attempted to quit did not influence the experienced craving severity over time, however, (4) patients who had received additional tapering off, on average, reported significantly more severe craving than patients who had only received a letter as an incentive to quit. Although benzodiazepine craving is prevalent among (former) long-term benzodiazepine users during and after discontinuation, craving severity decreases over time to negligible proportions. Self-reported craving can be longitudinally monitored and quantified by means of the BCQ.

[The first newborn with congenital rubella syndrome during the rubella epidemic in The Netherlands in 2004/'05]. / De eerste pasgeborene met congenitaal rubellasyndroom tijdens de rubella-epidemie in Nederland in 2004/'05.

A newborn male was diagnosed with congenital rubella syndrome. His 31-year-old mother had had erythematous exanthema during a period of amenorrhea lasting 7 weeks; she was not vaccinated and had never had a rubella infection. The infection was confirmed serologically. The mother gave birth to an icteric, microcephalic, dysmature neonate with hepatosplenomegaly and exanthema with multiple, small purple-red spots. Ultrasound cardiography revealed a persistently open arterial duct and a small defect of the ventricular septum. Radiological evaluation of the long bones showed the characteristic longitudinal lucent strands ('celery stalk appearance'). Ultrasound of the cerebrum showed diffuse widespread calcifications in the white matter and basal ganglia, striatal vasculopathy and diffuse parenchymal disorders. Psychomotor development was impaired. The patient was completely deaf in the left ear and had severely poor hearing in the right ear. After the introduction of the rubella vaccine in the Netherlands in 1974 a substantial decrease was seen in the incidence of rubella infections as well as congenital rubella syndrome. An epidemic of rubella infections has been present within the non-vaccinated population since September 2004. Recognition of the clinical symptoms and confirmation of the clinical suspicion with proper viral diagnostic methods are needed to control the current epidemic and to prevent secundary spread. Infants born with congenital rubella syndrome remain infectious to non-vaccinated individuals for a prolonged period of time; the virus is excreted in the urine and faeces. Long-term medical follow-up is necessary because the congenital rubella infection can cause abnormalities after the neonatal period.

[Central congenital hypothyroidism due to Graves' disease in the mother]. / Centrale congenitale hypothyreoïdie door ziekte van Graves bij de moeder.

Two male twins were born at a gestational age of 30 weeks. Five days after delivery, the mother was diagnosed with Graves' disease. The thyroid function in the neonates was therefore evaluated, which led to the detection of central congenital hypothyroidism (central CHT), even though the neonatal CHT-screening had been reported to be normal. Both boys were treated with thyroxine up to the age of nine months. It was then established that their development had been uneventful. Maternal Graves' disease can, due to the presence of anti-thyroid stimulating hormone (TSH) receptor antibodies and the maternal use of anti-thyroid drugs, result in thyroid dysfunction in the neonate. Neonates born to mothers with Graves' disease are at risk of developing central CHT. This occurs especially in children of mothers who are not treated or are inadequately treated during pregnancy. In view of the importance of thyroid hormone for brain development, children with central CHT are at risk for neurodevelopmental problems if thyroid dysfunction is not detected and treated early. The Dutch screening for congenital hypothyroidism is based on thyroxine (T4), TSH and thyroid-binding globulin. This makes it possible to detect central CHT. However, in prematurely born infants this disease may be missed because in this subgroup, referral is only based on increased TSH levels, which may not be present.

Modulation of collagen fiber orientation by strain-controlled enzymatic degradation.

Collagen fiber anisotropy has a significant influence on the function and mechanical properties of cardiovascular tissues. We investigated if strain-dependent collagen degradation can explain collagen orientation in response to uniaxial and biaxial mechanical loads. First, decellularized pericardial samples were stretched to a fixed uniaxial strain and after adding a collagen degrading enzyme (collagenase), force relaxation was measured to calculate the degradation rate. This data was used to identify the strain-dependent degradation rate. A minimum was observed in the degradation rate curve. It was then demonstrated, for the first time, that biaxial strain in combination with collagenase alters the collagen fiber alignment from an initially isotropic distribution to an anisotropic distribution with a mean alignment corresponding with the strain at the minimum degradation rate, which may be in between the principal strain directions. When both strains were smaller than the minimum degradation point, fibers tended to align in the direction of the larger strain and when both strains were larger than the minimum degradation, fibers mainly aligned in the direction of the smaller strain. However, when one strain was larger and one was smaller than the minimum degradation point, the observed fiber alignment was in between the principal strain directions. In the absence of collagenase, uniaxial and biaxial strains only had a slight effect on the collagen (re)orientation of the decellularized samples. STATEMENT OF SIGNIFICANCE: Collagen fiber orientation is a significant determinant of the mechanical properties of native tissues. To mimic the native-like collagen alignment in vitro, we need to understand the underlying mechanisms that direct this alignment. In the current study, we aimed to control collagen fiber orientation by applying biaxial strains in the presence of collagenase. We hypothesized that strain-dependent collagen degradation can describe specific collagen orientation when biaxial mechanical strains are applied. Based on this hypothesis, collagen fibers align in the direction where the degradation is minimal. Pericardial tissues, as isotropic collagen matrices, were decellularized and subjected to a fixed uniaxial strain. Then, collagenase was added to initiate the collagen degradation and the relaxation of force was measured to indicate the degradation rate. The V-shaped relationship between degradation rate and strain was obtained to identify the minimum degradation rate point. It was then demonstrated, for the first time, that biaxial strain in combination with collagenase alters the collagen fiber alignment from almost isotropic to a direction corresponding with the strain at the minimum degradation rate.

Stationary intraoral digital tomosynthesis using a carbon nanotube X-ray source array.

OBJECTIVES: Intraoral dental tomosynthesis and closely related tuned-aperture CT (TACT) are low-dose three-dimensional (3D) imaging modalities that have shown improved detection of multiple dental diseases. Clinical interest in implementing these technologies waned owing to their time-consuming nature. Recently developed carbon nanotube (CNT) X-ray sources allow rapid multi-image acquisition without mechanical motion, making tomosynthesis a clinically viable technique. The objective of this investigation was to evaluate the feasibility of and produce high-quality images from a digital tomosynthesis system employing CNT X-ray technology. METHODS: A test-bed stationary intraoral tomosynthesis unit was constructed using a CNT X-ray source array and a digital intraoral sensor. The source-to-image distance was modified to make the system comparable in image resolution to current two-dimensional intraoral radiography imaging systems. Anthropomorphic phantoms containing teeth with simulated and real caries lesions were imaged using a dose comparable to D-speed film dose with a rectangular collimation. Images were reconstructed and analysed. RESULTS: Tomosynthesis images of the phantom and teeth specimen demonstrated perceived image quality equivalent or superior to standard digital images with the added benefit of 3D information. The ability to "scroll" through slices in a buccal-lingual direction significantly improved visualization of anatomical details. In addition, the subjective visibility of dental caries was increased. CONCLUSIONS: Feasibility of the stationary intraoral tomosynthesis is demonstrated. The results show clinical promise and suitability for more robust observer and clinical studies.

Hydrolytic and oxidative degradation of electrospun supramolecular biomaterials: In vitro degradation pathways.

The emerging field of in situ tissue engineering (TE) of load bearing tissues places high demands on the implanted scaffolds, as these scaffolds should provide mechanical stability immediately upon implantation. The new class of synthetic supramolecular biomaterial polymers, which contain non-covalent interactions between the polymer chains, thereby forming complex 3D structures by self assembly. Here, we have aimed to map the degradation characteristics of promising (supramolecular) materials, by using a combination of in vitro tests. The selected biomaterials were all polycaprolactones (PCLs), either conventional and unmodified PCL, or PCL with supramolecular hydrogen bonding moieties (either 2-ureido-[1H]-pyrimidin-4-one or bis-urea units) incorporated into the backbone. As these materials are elastomeric, they are suitable candidates for cardiovascular TE applications. Electrospun scaffold strips of these materials were incubated with solutions containing enzymes that catalyze hydrolysis, or solutions containing oxidative species. At several time points, chemical, morphological, and mechanical properties were investigated. It was demonstrated that conventional and supramolecular PCL-based polymers respond differently to enzyme-accelerated hydrolytic or oxidative degradation, depending on the morphological and chemical composition of the material. Conventional PCL is more prone to hydrolytic enzymatic degradation as compared to the investigated supramolecular materials, while, in contrast, the latter materials are more susceptible to oxidative degradation. Given the observed degradation pathways of the examined materials, we are able to tailor degradation characteristics by combining selected PCL backbones with additional supramolecular moieties. The presented combination of in vitro test methods can be employed to screen, limit, and select biomaterials for pre-clinical in vivo studies targeted to different clinical applications.

Recombinant human erythropoietin increases blood pressure, platelet aggregability and platelet free calcium mobilisation in uraemic children: a possible link?

Recombinant human erythropoietin was administered to 10 uraemic children on chronic haemodialysis, all of whom responded by correcting their haemoglobin. In addition, they showed an increase in blood pressure; platelet aggregations, subnormal before therapy, improved during treatment. The intracellular free calcium concentration in platelets after thrombin stimulation also increased significantly during erythropoietin administration. We hypothesize that the effect of erythropoietin on platelet aggregability and on blood pressure may be due to an increase in the intracellular free calcium mobilisation in platelets and possibly in smooth muscle cells respectively.

The dependence of shrinkage stress reduction on porosity concentration in thin resin layers.

The development of polymerization contraction stress was determined as a function of the surface area of porosity, so that the contribution of voids in resin composite to stress relief could be investigated. Experiments were carried out on 200-microns-thick layers of resin bonded from wall to wall in a restrained condition. The resin samples were divided into three groups: Group A was without porosity, group B contained a small number of pores, and group C contained a large number of pores in comparison with group B. For each group, porosity area, maximal stress, and stress development rate were determined. The mean maximal stress and stress development rate were inversely proportional to the mean porosity surface. These characteristics differed significantly (p less than 0.01) between group A and C. For determination of whether shrinkage stress reduction has to be ascribed to flow from the outer surfaces of the voids or to inhibition of the setting reaction by oxygen in the voids, resin containing only nitrogen bubbles was also tested. The results indicated that both aspects contributed substantially to shrinkage stress relief. Incorporation of pores by the stirring of a luting cement contributes to stress reduction and can therefore be considered as a contribution to the maintenance of marginal integrity.