Evaluation of motion correction for clinical dynamic contrast enhanced MRI of the liver.

Motion correction of 4D dynamic contrast enhanced MRI (DCE-MRI) series is required for diagnostic evaluation of liver lesions. The registration, however, is a challenging task, owing to rapid changes in image appearance. In this study, two different registration approaches are compared; a conventional pairwise method applying mutual information as metric and a groupwise method applying a principal component analysis based metric, introduced by Huizinga et al (2016). The pairwise method transforms the individual 3D images one by one to a reference image, whereas the groupwise registration method computes the metric on all the images simultaneously, exploiting the temporal information, and transforms all 3D images to a common space. The performance of the two registration methods was evaluated using 70 clinical 4D DCE-MRI series with the focus on the liver. The evaluation was based on the smoothness of the time intensity curves in lesions, lesion volume change after deformation and the smoothness of spatial deformation. Furthermore, the visual quality of subtraction images (pre-contrast image subtracted from the post contrast images) before and after registration was rated by two observers. Both registration methods improved the alignment of the DCE-MRI images in comparison to the non-corrected series. Furthermore, the groupwise method achieved better temporal alignment with smoother spatial deformations than the pairwise method. The quality of the subtraction images was graded satisfactory in 32% of the cases without registration and in 77% and 80% of the cases after pairwise and groupwise registration, respectively. In conclusion, the groupwise registration method outperforms the pairwise registration method and achieves clinically satisfying results. Registration leads to improved subtraction images.

Physiotherapy in hip and knee osteoarthritis: development of a practice guideline concerning initial assessment, treatment and evaluation.

BACKGROUND: An update of a Dutch physiotherapy practice guideline in Hip and Knee Osteoarthritis (HKOA) was made, based on current evidence and best practice. METHODS: A guideline steering committee, comprising 10 expert physiotherapists, selected topics concerning the guideline chapters: initial assessment, treatment and evaluation. With respect to treatment a systematic literature search was performed using various databases, and the evidence was graded (1-4). For the initial assessment and evaluation mainly review papers and textbooks were used. Based on evidence and expert opinion, recommendations were formulated. A first draft of the guideline was reviewed by 17 experts from different professional backgrounds. A second draft was field-tested by 45 physiotherapists. RESULTS: In total 11 topics were selected. For the initial assessment, three recommendations were formulated, pertaining to history taking, red flags, and formulating treatment goals. Concerning treatment, 7 recommendations were formulated; (supervised) exercise therapy, education and self management interventions, a combination of exercise and manual therapy, postoperative exercise therapy and taping of the patella were recommended. Balneotherapy and hydrotherapy in HKOA, and thermotherapy, TENS, and Continuous Passive Motion in knee OA were neither recommended nor discouraged. Massage therapy, ultrasound, electrotherapy, electromagnetic field, Low Level Laser Therapy, preoperative physiotherapy and education could not be recommended. For the evaluation of treatment goals the following measurement instruments were recommended: Lequesne index, Western Ontario and McMaster Universities osteoarthritis index, Hip disability and Osteoarthritis Outcome Score and Knee injury and Osteoarthritis Outcome Score, 6-minute walktest, Timed Up and Go test, Patient Specific Complaint list, Visual Analoge Scale for pain, Intermittent and Constant OsteoArthritis Pain Questionnaire, goniometry, Medical Research Council for strength, handheld dynamometer. CONCLUSIONS: This update of a Dutch physiotherapy practice guideline on HKOA included 11 recommendations on the initial assessment, treatment and evaluation. The implementation of the guideline in clinical practice needs further evaluation.

Quality indicators indicate good adherence to the clinical practice guideline on "Osteoarthritis of the hip and knee" and few prognostic factors influence outcome indicators: a prospective cohort study.

BACKGROUND: Evaluation with quality indicators of adherence to the clinical practice guideline on "Osteoarthritis of the hip and knee" and of treatment outcomes. AIM: Furthermore to determine prognostic factors for outcome indicators. DESIGN: Prospective cohort study. POPULATION: Twenty-seven well informed physical therapists recorded patient and treatment characteristics of 103 community-dwelling patients referred by a general practitioner diagnosed with osteoarthritis of hip or knee. METHODS: With selected process and outcome indicators adherences to the guideline and treatment outcomes were assessed. Prognostic factors were calculated for Algofunctional Index (AI) and Visual Analogue Scale (VAS) for pain (decreases of ≤25% indicating "poor outcome"), number of sessions (>12) and duration of treatment (>6 weeks), using multivariate logistic regression models. RESULTS: Process indicators showed that information & advice was given to 95% of the patients and functions and activities were exercised in 97% respectively 87%. Aftercare was arranged for 46% of the patients, that was clearly lower than the benchmark of 90%. Outcome indicators VAS-pain and AI decreased by 45% and 36%, respectively. The combination ">12 months" duration of complaints and age ≥65" was associated with a "poor outcome" on AI (OR 2.53; 95% CI 1.01-6.38). Co-morbidity (OR 2.8; 95% CI 1.17-6.88), and "VAS-pain at baseline ≥51 mm" (OR 3.1; 95% CI 1.34-7.23) were associated with a higher number of treatment sessions. CONCLUSION AND CLINICAL REHABILITATION IMPACT: and Quality indicators showed that a group of well-informed physical therapists could to a large extent adhere to key recommendations of the guideline and that clinically relevant improvements were obtained in terms of pain and physical functioning. Prognostic factors for poorer outcome on outcome indicators were comorbidity, a higher pain score at baseline and the combination ">12 months' duration of complaints and age ≥65".

Uncertainty and sensitivity analysis of spatial predictions of heavy metals in wheat.

Heavy metals seriously threaten the health of human beings when they enter the food chain. Therefore, policymakers require precise predictions of heavy metal concentrations in agricultural crops. In this paper we quantify the uncertainty of regression predictions of Cd and Pb in wheat (Triticum aestivum L.) and the contributions to the uncertainties in these predictions associated with inputs to the regression model. For each node of the 500- x 500-m grid covering the arable soils in The Netherlands, a latin hypercube sample size of 1000 is constructed from the uncertainty distributions of the explanatory variables (pH, soil organic matter [SOM], and heavy metal concentration in soil), the regression coefficients, and the random term of the regression model. This sample is used as input for the regression model to obtain 1000 values from the uncertainty distributions of the log(Cd) and log(Pb) concentration in wheat. There were no nodes where the recent EU quality standards for Cd and Pb (0.2 mg kg(-1) fresh wt.) in wheat were almost certain to be exceeded. For most nodes with clay soils, the quality standard for Cd in wheat almost certainly will not be exceeded; for Pb this is much less certain. The uncertainty in the Cd concentration in soil contributes most to the uncertainty in the predicted Cd concentrations in wheat (36% on the average), followed by the random term of the regression model (23%). For Pb the contribution of the random term is by far the largest (52%).

[Splenectomy in children; indications and surgical aspects]. / Splenectomie bij kinderen; indicaties en chirurgische aspecten.

There are no hard indications for splenectomy in children. The single most generally accepted indication is the more severe form of congenital spherocytosis. Idiopathic thrombocytopenia purpura is only an indication if there is a severe bleeding tendency. Other than local conditions involving the spleen, there seem to be no good indications for partial splenectomy. Ablation by means of embolisation has not gained popularity. Laparoscopic splenectomy appears to be better than splenectomy via laparotomy, but sound scientific evidence for this is not yet available. There appears to be an increased incidence of portal vein thrombosis immediately after splenectomy. The value of thrombosis prophylaxis has not yet been investigated.

Are clinical parameters valuable prognostic factors in childhood primitive neuroectodermal tumors? A multivariate analysis of 105 cases.

BACKGROUND: Medulloblastoma is one of the most frequent brain tumors in children. Long-term survivors are often confronted with serious late sequelae, caused by the therapy. Therefore, prognostic markers must be identified that allow the children to be assigned to different treatment schedules according to their predicted outcome. PATIENTS AND METHODS: The medical data of 110 children with a medulloblastoma or central primitive neuroectodermal tumor (PNET), that were admitted to the Emma Kinderziekenhuis in Amsterdam were analyzed by univariate and multivariate analyses. RESULTS: In univariate analysis the following characteristics had a significant influence on progression free survival (PFS): (a) presence of meningeal metastases at the time of diagnosis, (b) presence of tumor cells in the cerebrospinal fluid before or after surgery, (c) extent of resection, (d) necessity for permanent cerebrospinal fluid (CSF) shunting and (e) radiation dose to the posterior fossa. On multivariate analysis only the presence of metastases and the radiation dose to the posterior fossa retained significance. CONCLUSION: At the time of diagnosis, no reliable clinical prognostic markers are available for the majority of patients. Further molecular studies must be undertaken to identify such prognostic factors.

Interleukin 10 mitigates the development of the zymosan-induced multiple organ dysfunction syndrome in mice.

We investigated the effect of interleukin 10 on the development of zymosan-induced multiple organ dysfunction syndrome (MODS) and on plasma concentrations and production capacity of tumour necrosis factor (TNF)-alpha by peritoneal cells. Groups of C57BL/6 mice received a single intraperitoneal injection with zymosan, a cell wall component of Saccharomyces cerevisiae, at day 0. Daily doses of human recombinant interleukin 10 (IL-10: 10 or 50 microg/kg) were given intraperitoneally either starting directly before administration of zymosan (day 0), or 5 or 8 days after administration of zymosan. The animals were monitored for survival, condition, body weight and temperature. On day 12 all surviving animals were killed to obtain plasma, organs and peritoneal cells. Plasma concentrations of TNF-alpha and lipopolysaccharide-stimulated production of TNF-alpha by peritoneal cells were measured; organ weights were registered as an indicator for organ damage. IL-10 improves survival and clinical condition and also reduces organ damage, but only at the highest dose used and only when started simultaneously with the administration of zymosan. Circulating TNF-alpha concentrations 12 days after zymosan are not affected by any of the IL-10 schedules used. However, lipopolysaccharide-stimulated production of TNF-alpha by peritoneal cells is increased, in a dose- and time-dependent fashion. The anti-inflammatory cytokine IL-10 is able to attenuate the development of MODS in this model, but only when given simultaneously with zymosan, and in high dosages.

Striated muscle microvascular response to zymosan-induced generalized inflammation in awake hamsters.

The effect of zymosan-induced generalized inflammation on the microcirculation of distant striated skin muscle was studied for a 12 day period in awake Syrian golden hamsters (n = 18) using the dorsal skinfold chamber model and intravital fluorescence microscopy. Intraperitoneal zymosan exposure (125 mg/100 g body weight) induced significant nutritive perfusion failure in the distant striated muscle tissue at Day 1 without complete recovery over the 12 day observation period, as indicated by the marked reduction of functional capillary density when compared with both baseline values and values of sham-treated control animals. Moreover, intraperitoneal zymosan exposure induced endothelial disintegration, as demonstrated by the continuous increase of macromolecular leakage throughout the 12 days of observation. Strikingly, zymosan did not induce significant leukocyte adherence to the endothelial lining of postcapillary and collecting venules of the striated muscle tissue. Thus, we conclude that in this model of generalized inflammation nutritive perfusion failure and loss of endothelial integrity in distant striated muscle is not mediated by activated leukocytes, but must rather be attributed to direct toxic effects of mediators, elicited by the local (intraperitoneal) zymosan challenge and systemically released.

Chlorpromazine down-regulates tumor necrosis factor-alpha and attenuates experimental multiple organ dysfunction syndrome in mice.

OBJECTIVES: Chlorpromazine is a known modulator of tumor necrosis factor (TNF)-alpha production. TNF-alpha is thought to be a key mediator in the development of the multiple organ dysfunction syndrome (MODS). We investigated the effect of chlorpromazine on the development of zymosan-induced MODS in mice and on plasma TNF-alpha concentrations and production capacity of TNF-alpha by peritoneal cells. DESIGN: Prospective, controlled laboratory study on zymosan-induced generalized inflammation in mice. SETTING: Animal research laboratory. SUBJECTS: C57BL/6 mice received daily doses (4 mg/kg body weight) of chlorpromazine, beginning 2 days before or 5 days after zymosan administration. In additional groups, the daily chlorpromazine dose of 4 mg/kg started 5 days after zymosan was increased 2 days later to 8 or 16 mg/kg/day. MEASUREMENTS AND MAIN RESULTS: The animals were monitored for survival, condition, body weight, and body temperature. Twelve days after zymosan was administered, all surviving animals were killed to obtain plasma, organs, and peritoneal cells. Plasma concentrations of TNF-alpha and lipopolysaccharide-stimulated production of TNF-alpha by peritoneal cells were measured. Organ weights were recorded as an indicator for organ damage. Although survival was not improved when the animals were treated with chlorpromazine, the chlorpromazine-treated survivors showed improved body weight and temperature when compared with the animals receiving zymosan only. Also, the organ weights and lung damage improved significantly in the treated group. Chlorpromazine was most effective when started before zymosan administration. When administered afterward, clinical improvement declined with the dose. In all cases, circulating TNF-alpha and production of TNF-alpha by peritoneal macrophages were lowered toward control values. CONCLUSION: Chlorpromazine mitigates the development of zymosan-induced MODS, possibly by reducing macrophage TNF-alpha production.

A monoclonal antibody against tumour necrosis factor-alpha improves survival in experimental multiple organ dysfunction syndrome.

A single intraperitoneal administration of zymosan induces multiple organ dysfunction syndrome (MODS) in C57BL/6 mice. The authors investigated the effect of a monoclonal antibody V1q against murine tumour necrosis factor alpha (TNF-alpha) on the development of zymosan-induced MODS and on plasma concentrations and the production capacity of interleukin 6 (IL-6) by peritoneal cells. C57BL/6 mice received doses of V1q starting either simultaneously with administration of zymosan every four days, or from 4 or 8 days after administration of zymosan onwards. The animals were monitored for survival, condition, and body weight and temperature. Twelve days after zymosan all surviving animals were killed to obtain plasma, organs and peritoneal cells. Plasma concentrations of IL-6 and lipopolysaccharide-stimulated production of IL-6 by peritoneal cells were measured; organs were weighed as an indicator for organ damage and lung damage was assessed macroscopically. Survival improved when the animals were treated with V1q starting at either time point, and a subpopulation developed from the group receiving V1q from day 0 onwards that displayed improved body weight and temperature when compared to the animals receiving zymosan only. Also, the wet organ weights improved in this subgroup, indicating a beneficial effect of the monoclonal antibody. However, V1q administered could neither decrease the circulating IL-6 concentrations toward control values, nor did V1q treatment normalize IL-6 production capacity (stimulated or unstimulated). The development of zymosan-induced MODS can be attenuated by the monoclonal antibody V1q.

Gradual development of organ damage in the murine zymosan-induced multiple organ dysfunction syndrome.

A well defined animal model is a prerequisite to test intervention strategies aimed at preventing the development of the multiple organ dysfunction syndrome. This study compares changes in clinical parameters to histopathologic changes in tissues, observed over a 12 day period after a single intraperitoneal injection of zymosan in C57BL/6 mice. Administration of zymosan induced gradual and progressive changes in wet and dry organ weight of the liver, kidneys, and particularly, lungs and spleen that correlated with increasing histopathology. From 6 days after zymosan injection onwards, hemorrhagic spots were found in the lungs evolving into massive hemorrhages at 12 days, when thickened interstitial walls and loss of the honey comb-like structures were observed. The liver displayed progressive accumulation of macrophage-like and mononuclear cells. After 12 days, numerous granuloma-like structures were disseminated throughout the liver parenchyma. The spleen displayed great changes in red and white pulp with increasing numbers of megakaryocytes and plasma-like cells. In the kidneys, necrosis of the tubular epithelium adjacent to granulomas on the ventral (peritoneal) side was found. In mice, a single intraperitoneal challenge with zymosan leads to progressive multiple organ damage, which becomes apparent at some time after the insult. This animal model displays a number of features encountered in human multiple organ dysfunction syndrome and appears suitable to conduct intervention studies.

Increasing cytotoxic activity and production of reactive oxygen and nitrogen intermediates by peritoneal macrophages during the development of multiple organ dysfunction syndrome in mice.

A major problem in the intensive care unit nowadays is the development of multiple organ dysfunction syndrome (MODS), a cumulative sequence of progressive deterioration of organ functions. While the pathogenic pathways of MODS remain to be elucidated, it is assumed that cells of the host defence system, especially the macrophages, are altered in their function. During the development of MODS it is assumed that macrophages are overactivated and that an exaggerated inflammatory response may contribute to its pathogenesis. In order to gain insight into the alterations of the functional status of the macrophage during the development of MODS, a series of macrophage functions was measured in the subsequent phases of zymosan induced generalized inflammation in mice. Male C57BL/6 mice received a single dose of zymosan intraperitoneally and groups of animals were killed after 2, 5, 8, and 12 days. Peritoneal macrophages were collected for in vitro assessment of the ADCC, the production of superoxide (O2-) and nitric oxide (NO), and complement mediated phagocytosis and intracellular killing of Staphylococcus aureus. A single intraperitoneal injection with zymosan resulted in a three-phase illness. During the third phase the animals developed MODS-like symptoms. Peritoneal cells from control animals produced very low to non-detectable amounts of O2- and NO, and the cytotoxic activity was also low. During the development of MODS, from day 7 onwards, the ability to produce O2- and NO2- became strongly elevated, as did the cytotoxic activity. These findings are in parallel with the development of MODS whereas the phagocytic and killing capacity remained essentially unaltered. The changes found could be detrimental for the organism, thus possibly contributing to the onset and development of MODS.

Inflammatory cytokines in an experimental model for the multiple organ dysfunction syndrome.

OBJECTIVE: To investigate the alterations in circulating pro-inflammatory cytokines and cytokine production by peritoneal macrophages during the development of multiple organ dysfunction syndrome. DESIGN: Prospective, controlled laboratory study on zymosan-induced generalized inflammation in mice. Single intraperitoneal administration of zymosan induces, over a 12-day period, a triphasic illness in mice; the third phase, from day 6 onward, resembles multiple organ dysfunction syndrome. SETTING: Animal research laboratory. SUBJECTS: C57BL/6CRW mice received a single intraperitoneal dose of zymosan on day 0, and standard numbers of animals were killed at different time points up until day 12. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of interleukin (IL)-1 alpha and IL-1 beta, IL-6, and tumor necrosis factor (TNF)-alpha were measured from 3 hrs to 12 days after administration of zymosan. At the same time points, both lipopolysaccharide-stimulated and unstimulated production of these cytokines by peritoneal macrophages were measured in vitro. Plasma TNF and IL-6 concentrations transiently increased during the first 24 hrs after administration of zymosan. After 8 days, a prominent peak of biologically inactive TNF was observed. Both unstimulated and lipopolysaccharide-stimulated cytokine production by peritoneal cells showed profound changes during the experimental period. CONCLUSIONS: These findings seem to confirm our hypothesis that the macrophages are in a continuously activated state and altered in their function, when the animals develop multiple organ dysfunction syndrome. Further studies are needed to elucidate what happens with these cytokines at the tissue level, to better understand the pathophysiology of multiple organ dysfunction syndrome.

Cerebrospinal fluid free kappa light chains versus IgG findings in neurological disorders: qualitative and quantitative measurements.

In this study free kappa light chains in cerebrospinal fluid (CSF) were determined both by an affinity mediated capillary blotting technique after isoelectric focusing (IEF) in agarose gel and by a quantitative enzyme linked immunosorbent assay (ELISA). The free kappa results were compared with the IgG findings in 4 neurological patient groups with a distinct CSF IgG pattern: (1) CSF without oligoclonal IgG bands, (2) CSF with serum derived IgG bands, (3) CSF restricted IgG bands and (4) CSF restricted and serum derived IgG bands. Oligoclonal free kappa bands are nearly absent in CSF of groups 1 + 2, and present in 88% of group 3 and 84% of group 4 patients. We could also establish free kappa indices from specimens in the 4 groups in analogy to IgG indices. Group 1 had a median free kappa index of 1.1, group 2: 1.0 and groups 3 + 4: 10.0. The correspondence between immunoblot and index findings for free kappa is better than for IgG. Free kappa index is more sensitive but somewhat less specific than IgG index for establishing intrathecal immune production.

Immunoglobulin G, A and M light chain ratio in children.

Values for the kappa/lambda light chain ratio in immunoglobulins G, A and M and the total kappa/lambda ratio, measured by enzyme linked immunosorbent assay, were evaluated in serum samples from different age groups (114 children, aged from 1 month to 15 years, and 20 adults). The IgG kappa/lambda ratio decreased in the first 6 months and subsequently increased slowly during childhood towards the adult value of 2.0. The IgM kappa/lambda ratio increased at a greater rate than IgG kappa/lambda ratio in the first years of life and thereafter rose slightly throughout childhood to reach an adult value of 1.7. A decreasing IgA kappa/lambda ratio was found from 1 month of age onwards to an adult value of 1.1. The pattern of total kappa/lambda ratio was similar to the IgG kappa/lambda ratio with an adult value of 2.0.

Determination of kappa and lambda light chains in serum immunoglobulins G, A and M.

An enzyme-linked immunosorbent assay is described for measuring kappa and lambda light chains within each of the serum immunoglobulin classes G, A and M. The detection limit was 0.06 U/L for total IgG, IgG kappa and IgG lambda, 0.2 U/L for total IgA, IgA kappa and IgA lambda and 0.5 U/L for total IgM, IgM kappa and IgM lambda. The concentrations of kappa plus lambda light chains from the three different immunoglobulins correlated well within those of total immunoglobulin G, A and M as measured by enzyme-linked immunosorbent assay or by immunonephelometry. Adult values for the kappa/lambda light chain ratio were found to be 2.0 for IgG kappa/lambda, 1.1 for IgA kappa/lambda and 1.7 for IgM kappa/lambda.

Ratiometric measurement of intracellular pH in cultured human keratinocytes using carboxy-SNARF-1 and flow cytometry.

In this study we describe a method to measure intracellular pH in cultured human keratinocytes using flow cytometry. Keratinocytes pose a technical problem because the population is heterogeneous with respect to size and metabolic activity (nonspecific esterase activity), resulting in variability in dye uptake. In order to compensate for this, dyes were selected that change colour with pH. The ratio of fluorescence intensities at two wavelengths was recorded and used as a measure of intracellular pH by reference to the pH in the presence of the proton ionophore nigericin. However, methods published till now do not routinely combine the ratiometric technique and excitation with an argon ion laser set at 488 nm. Therefore we have tested the recently developed pH-sensitive dye carboxyseminaphthorhodafluor-1 (SNARF-1) as a possible candidate for flow cytometric pH measurements and compared it with 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein (BCECF) and 2,3-dicyanohydroquinone (DCH) with respect to emission spectra, resolution, range, and stability of cellular fluorescence. SNARF-1 had a practical and stable excitation wavelength of 488 nm rather than UV, it offered the possibility of ratiometric measurements on the basis of a real emission shift, and had superior resolution for the pH range 7-8. With SNARF-1 we found that keratinocytes cultured under low serum conditions (0.2%) contain a higher proportion of cells with relatively low intracellular pH compared to high serum cultures (6%). Furthermore, pH changes were followed by changes in relative DNA content. These findings suggest that intracellular pH can be an early functional proliferation marker for human keratinocytes.

Fatal neonatal cardiomyopathy associated with cataract and mitochondrial myopathy.

Three patients suffering from the neonatal form of a syndrome characterized by congenital cataract, hypertrophic cardiomyopathy, and mitochondrial myopathy are described. The patients died at 7, 10 and 18 days, respectively from cardiorespiratory failure. Mitochondrial abnormalities were observed in the heart and skeletal muscle. Despite the presence of a severe lactic acidaemia pointing to a disturbed pyruvate oxidation rate in vivo, a normal pyruvate oxidation rate was demonstrated in skeletal muscle homogenates. The activities of several enzymes of the mitochondrial respiratory chain appeared to be normal, indicating an intact respiratory chain. A myoglobinopenia could be excluded. The activities of some mitochondrial enzymes and the concentration of myoglobin increase with age.

Screening for microalbuminuria in patients with diabetes mellitus: frozen storage of urine samples decreases their albumin content.

The influence of storage on urinary albumin concentration was prospectively studied with use of overnight urine specimens (Albustix negative) from 73 diabetic patients. From each urine sample four aliquots were taken. One was stored at 4 degrees C and assayed within two weeks, the other three were stored at -20 degrees C and assayed within two weeks and after two and six months. Albumin concentration was measured with laser immunonephelometry. The detection limit, 1 mg/L, suffices for the screening of diabetic patients for microalbuminuria. After storage for two and six months at -20 degrees C, significantly lower albumin concentrations were found. The difference was mainly caused by lower concentrations found in urine samples in which a precipitate had formed, which was the case in 22 and 25 samples, respectively. Thus, freezing of urine samples for determination of low concentrations of albumin may yield falsely low results. Urine samples are best stored at 4 degrees C and assayed within two weeks.

Enrichment of subgingival microflora on human serum leading to accumulation of Bacteroides species, Peptostreptococci and Fusobacteria.

This study was undertaken to identify ecological factors that favour opportunistic pathogenic species in the subgingival microflora. In a first approach, human serum as a substitute for gingival exudate, was used for batch-wise enrichment of subgingival plaque. The microflora resulting after 5-6 enrichment steps consisted of black-pigmented and non-black-pigmented Bacteroides species, Peptostreptococcus micros and Fusobacterium nucleatum as the main organisms. It is noted that the same group of species was found to be enriched independent upon the origin of the subgingival plaque sample. It was suggested that these organisms are favoured by the increased flow of gingival exudate during inflammation. The consortium of organisms was capable of selective degradation of serum (glyco-)proteins. Four different types of degradation occurred. After a prolonged period of growth complete degradation of immunoglobulins, haptoglobin, transferrin and complement C3c was observed. Partial degradation of immunoglobulins, haptoglobin, transferrin, albumin, alpha 1-antitrypsin and complement C3c and C4 was generally observed after 48 h of growth. Besides, immunoglobulin protease activity yielding Fc and Fab fragments was found. The consortium was also capable of consuming carbohydrate side-chains as indicated by an altered electrophoretic mobility of the serum glycoproteins.