The virtual crossmatch--a screening tool for sensitized pediatric heart transplant recipients

Heart transplantation in the setting of human leukocyte antigen (HLA) sensitization is challenging, as a time-consuming prospective crossmatch (XM) may be required, severely limiting the number of potential donors. We evaluated a 'virtual XM', defining a positive virtual XM as the presence of recipient pre-formed anti-HLA antibodies to the prospective donor HLA type, and compared the virtual XM to a standard direct XM. Bead-based flow cytometric analysis was used to identify anti-HLA antibody (Ab) present in a child listed for heart transplantation. Using recipient serum, direct-flow cytometric T- and B-cell XM were run for potential donors against whose HLA type the recipient had specific antibodies (group 1, n = 7) and for potential donors with predicted compatible HLA types by virtual XM (group 2, n = 7). Results were expressed as median channel difference (MCD) between the control and recipient serum. A positive T-cell XM was defined as MCD > 50, whereas MCD > 100 constituted a positive B-cell result. The rate of T-cell reactivity was significantly less in group 2 than in group 1 (29% vs. 100%, p = 0.02); similarly, B-cell reactivity was also less for group 2 (14% vs. 100%, p = 0.005). The virtual XM was 100% sensitive in detecting positive flow cytometric XM results for T and B cells. Although only 72% specific in predicting a negative T-cell XM, and 86% specific for negative B-cell XM, the false negatives were weakly positive and would probably have been clinically acceptable. Currently, potentially suitable donor organs are often declined for lack of a prospective XM; these organs may ultimately be allocated to more distant recipients or perhaps not used at all. While further studies are needed, virtual XM has the potential to improve availability of organs for sensitized patients and improve the overall allocation process.

The WAIS-R factors: usefulness and construct validity in neuropsychological assessments

One-hundred and twelve patients were administered the Wechsler Adult Intelligence Scale-Revised (WAIS-R), an abbreviated Wechsler Memory Scale-Revised, and the Halstead-Reitan Neuropsychological Test Battery. In order to replicate an earlier study (Sherman, Strauss, Spellacy, & Hunter, 1995), correlations were generated between the WAIS-R factor scores and neuropsychological and memory tests. The Verbal Comprehension factor (Factor 1) correlated with Speech Sounds Perception Test (SSPT), the Seashore Rhythm Test (SSRT), the Category Test, and memory indices. The Perceptual Organizational factor (Factor 2) correlated with the time, memory, and location scores of the Tactual Performance Test, the SSPT, SSRT, the Category Test, Trails A, Trails B, memory indices, and finger tapping. The Freedom From Distractibility factor (Factor 3) was correlated with the Category Test, the SSPT, the SSRT, Trails A, Trails B, immediate Logical Memory, and Visual Reproduction. Modest correlations suggest that the WAIS-R factors may be useful for understanding underlying cognitive performance and can be functional for generating hypotheses, but should not be utilized exclusively to make clinical inferences.

Reproducibility of head-up tilt-table testing in pediatric patients with neurocardiogenic syncope

The aim of this study is to assess the reproducibility of a head-up tilt-table test protocol so it may be used to more accurately evaluate the effectiveness of a treatment protocol. Children between the ages of 10 and 18 years presenting to the cardiology department at Children's Hospital of Wisconsin with a diagnosis of neurocardiogenic syncope were eligible for the study. The patients were tilted to 70 degrees for 30 minutes or until a positive test occurred. Patients with a positive test were retilted using the same protocol. Parameters measured included heart rate, blood pressure, and the presence or absence of syncope or presyncope. Twenty-two patients were enrolled in the study. Seventeen patients had a positive test on first tilt. Fifteen had a positive tilt test on the second tilt. There were no significant differences between the two tilts with regard to mean differences of baseline heart rate, systolic blood pressure, or mean arterial pressure. There were no significant differences between the two tilts with regard to mean differences in time until symptoms, heart rate, systolic blood pressure, or mean arterial blood pressure at time of symptoms. This study shows that the head-up tilt-table test protocol used is reproducible in adolescents with the diagnosis of neurocardiogenic syncope.

Tracheal surgery in children

BACKGROUND

The aim of this study is to show that five distinct types of tracheal anomalies should be differentiated with respect to therapy and prognosis.

METHODS

The records of 12 infants and children seen over a period of 20 years for different tracheal anomalies such as laryngotracheal stenosis (n = 3), long or short-segment stenosis of the upper (n = 2), middle (n = 6), and lower (n = 1) trachea were reviewed. In addition to these 12 patients with congenital stenosis, 3 other patients needed tracheal resections because of oncologic or traumatic disease: in 2, the trachea was infiltrated by a papillary carcinoma of the thyroid gland and in one, the upper part of the trachea was injured by an oral explosion accident. 25 patients presenting during the same period for other tracheal pathologies including esophagotracheal cleft syndrome (n = 7), tracheomalacia (n = 4), total tracheal agenesis (n = 3), or for placement of a tracheostomy (n = 11) due to other diseases were excluded from this study.

RESULTS

There was 1 early death after repair of a laryngotracheal stenosis by cricoid-split and cricoid-splint due to both cerebral hemorrhage and cardiac insufficiency secondary to Fallot's tetralogy. Another child died four weeks after slide tracheoplasty as a result of hypoxic cerebral lesions induced by severe central catheter-related septicemia. One child with therapy-resistant obstructing granulation tissue which developed after a slide tracheoplasty required a tracheostomy. The patient with the tracheal injury died after another accident one year after discharge. All other patients (n = 11) are doing well.

CONCLUSIONS

With respect to therapy of congenital and post-intubation tracheal stenosis, four types should be distinguished. Each of these types requires an adequate surgical procedure. The most important postoperative problem in tracheal surgery is the development of granulation tissue. However, the pathogenesis of granulation is still unknown.

Right esophageal lung in a preterm child with VACTERL association and Mayer-Rokitansky-Kuster-Hauser syndrome

We report on a preterm girl (birth weight 1,200 g) with a right esophageal lung in esophageal atresia type VIag (according to the extended classification of Kluth). Additionally, the child suffered from an atrioseptal defect, a dextrocardia with a left descending aorta, a duodenal atresia, a high type of anal atresia (VACTERL association), agenesis of the left kidney, and agenesis of the vagina, uterus, and ovarian tubes (Mayer-Rokitansky-Kuster-Hauser syndrome or incomplete MURCS association). The child was treated with an emergency gastrostomy because of increasing abdominal dilatation. Thereafter, the parents refused further surgical treatment, and the child was maintained on basic therapy. After an uneventful period of 4 weeks, the child died of an acute massive aspiration. This case shows that sufficient spontaneous ventilation is possible in esophageal lung as long as a gastrostomy is kept on suction to prevent overinflation of the affected lung and the stomach. Ethical aspects have to be considered when treatment is planned in cases of prematurity and associated malformations when a chance of good survival is rather limited. The stepwise approach as proposed in the present case appears to be the only possible therapeutic regimen that can be offered in this complicated condition.

Screening of epoxide hydrolase producing microorganisms for biotransformation of deoxynivalenol

Deoxynivalenol (DON) transformation products from selected time course experiments were analyzed by thin-layer chromatography. With the strainAlternaria alternata f. sp.lycopersici AS27-3, one major metabolite of DON in ethyl acetate was observed. This unidentified metabolite was more polar than DON and has a Rf value of 0.71. Derivatization indicated that this metabolite was probably an unidentified trichothecene. Screening of 29 other microbial isolates (bacteria, yeast, filamentous fungi) for DON transformation did not result in any active organism.

Design of oligolactone-based scaffolds for bone tissue engineering

Novel difunctional oligolactone macromers have been synthesized by ring-opening oligomerization of various lactones (L-lactide, glycolide, p-dioxanone) in the presence of suitable diols (propane-1,2-diol, dianhydro-D-glucitol) and subsequent endcapping of the formed oligolactones with methacrylate moieties. Based on these macromers, two fabrication procedures were developed to fabricate highly porous scaffolds and the material properties including in vitro biodegradation behaviour of the resulting polymeric scaffolds were investigated. Preliminary in vitro studies on the cytocompatibility of the fabricated scaffolds and on osteoblast cultivation on the optimized polymeric materials demonstrated that the oligolactide based polymer networks possess an excellent biocompatibility and that they are promising candidates as scaffolds in bone tissue engineering.

Cost-effectiveness of Project ADAM: a project to prevent sudden cardiac death in high school students

Public access defibrillation (PAD) in the adult population is thought to be both efficacious and cost-effective. Similar programs aimed at children and adolescents have not been evaluated for their cost-effectiveness. This study evaluates the potential cost-effectiveness of implementing Project ADAM, a program targeting children and adolescents in high schools in the Milwaukee Public School System. Project ADAM provides education about cardiopulmonary resuscitation (CPR) and the warning signs of sudden cardiac death (SCD) and training in the use and placement of automated external defibrillators (AEDs) in high schools. We developed decision analysis models to evaluate the cost-effectiveness of the decision to implement Project ADAM in public high schools in Milwaukee. We examined clinical model and public policy applications. Data on costs included estimates of hospital-based charges derived from a pediatric medical center where a series of patients were treated for SCD, educational programming, and the direct costs of one AED and training for 15 personnel per school. We performed sensitivity analyses to assess the variation in outputs with respect to changes to input data. The main outcome measures were Life years saved and incremental cost-effectiveness ratios. At an arbitrary societal willingness to pay $100,000 per life year saved, the policy to implement Project ADAM in schools is a cost-effective strategy at a threshold of approximately 5 patients over 5 years for the clinical model and approximately 8 patients over 5 years for the public policy model. Implementation of Project ADAM in high schools in the United States is potentially associated with an incremental cost-effectiveness ratio that is favorable.

Zebrafish beta tubulin 1 expression is limited to the nervous system throughout development, and in the adult brain is restricted to a subset of proliferative regions

Tubulin, the building block of microtubules, consists of an alpha and beta subunit, each in itself a family of several highly homologous isotypes. Abundance, tissue specificity, developmental regulation, and possibly function vary between isotypes. Six isotypes of beta tubulin (class I to class VI) have been cloned from several vertebrate species. Class I beta tubulin is believed to be widely expressed, but has not been studied by in situ hybridization in any vertebrate species so far. We have cloned a beta tubulin from zebrafish that appears most similar to other vertebrate class I tubulins and name it zbeta1 tubulin, accordingly. We report a distinct expression pattern of zbeta1 tubulin in the zebrafish embryo in restricted regions of the peripheral and central nervous system that comprise early-differentiating neurons. The expression pattern changes during development and in the adult zebrafish expression mostly is confined to a subset of proliferative zones that include the subependymal zone around the telencephalic ventricle, zones in the preoptic and hypothalamic area and in the olfactory epithelium. Thus, zbeta1 tubulin is expressed with remarkable selectivity during neuronal differentiation and neurogenesis in the embryonic and adult nervous system, respectively.

Ultrasonic wave propagation in human cancellous bone: application of Biot theory

Ultrasonic wave propagation in human cancellous bone is considered. Reflection and transmission coefficients are derived for a slab of cancellous bone having an elastic frame using Biot's theory modified by the model of Johnson et al. [J. Fluid Mech. 176, 379-402 (1987)] for viscous exchange between fluid and structure. Numerical simulations of transmitted waves in the time domain are worked out by varying the modified Biot parameters. The variation is applied to the governing parameters and is about 20%. From this study, we can gain an insight into the sensitivity of each physical parameter used in this theory. Some parameters play an important role in slow-wave wave form, such as the viscous characteristic length lambda and pore fluid bulk modulus Kf. However, other parameters play an important role in the fast-wave wave form, such as solid density rhos and shear modulus N. We also note from these simulations that some parameters such as porosity phi, tortuosity alpha(infinty), thickness, solid bulk modulus Ks, and skeletal compressibility frame Kb, play an important role simultaneously in both fast and slow wave forms compared to other parameters which act on the wave form of just one of the two waves. The sensitivity of the modified Biot parameters with respect to the transmitted wave depends strongly on the coupling between the solid and fluid phases of the cancellous bone. Experimental results for slow and fast waves transmitted through human cancellous bone samples are given and compared with theoretical predictions.

Implantable cardioverter defibrillator therapy in children with long QT syndrome

We report our experience with implantable cardioverter defibrillator (ICD) implantation and follow-up in high-risk patients with congenital long QT syndrome (LQTS). Congenital LQTS is associated with significant risk of malignant ventricular arrhythmias and sudden cardiac death (SCD). ICD implant is recommended for prevention of SCD in this patient population, but there are few published data regarding the efficacy and side effects of such therapy. We report our experience with 12 patients who underwent ICD implant for high-risk LQTS at our center in the past 5 years with respect to implant complications, appropriate and inappropriate therapies, device follow-up, and the impact on lifestyle. During a follow-up of 34.7+/-16.6 months, appropriate therapies were noted in 5, inappropriate therapies in 4, and no therapies in 3 patients. Clusters of appropriate therapies were seen in 3 patients, 1 of whom subsequently died. Female sex and congenital deafness appear to be associated with a higher risk of appropriate therapies. One patient experienced two complications at implant that were successfully treated. ICD implantation in LQTS patients presenting with SCD or recurrent syncope despite beta-blocker therapy appears to be justified in preventing SCD risk. In asymptomatic siblings of SCD patients, the benefits of ICD implant are not clear from our data.

Genetic dissection of corticosteroid receptor function in mice

Functional genomic technologies, including artificial chromosome-based transgenesis and conditional gene targeting, allowed us to generate mouse models harboring genes with loss-of-function mutations, gain-of-function mutations, spatially and/or temporally restricted mutations, tissue-specific mutations, and function-selective mutations. This kind of "allelic series" for corticosteroid receptors in mouse models provides a very useful resource for the molecular understanding of corticosteroid function in vivo. These models will also support the identification of steroid receptor target genes in order to define a steroid signaling cascade in molecular terms. They provide opportunities for the identification of compounds that regulate steroid receptors in a tissue-specific and function-selective manner. For example, selective glucocorticoid receptor modulators preventing receptor dimerization and DNA binding can be expected to reduce osteoporotic and/or diabetogenic side effects, but to display partial or full anti-inflammatory potential. Thus, these mouse models will help to evaluate distinct steroid receptor functions for therapeutic intervention.

Determination of transport parameters in air-saturated porous materials via reflected ultrasonic waves

An ultrasonic reflectivity method of evaluating the acoustic parameters of porous materials saturated by air (or any other gas) is discussed. The method is based on experimental detection of waves reflected at normal incidence by the first and second interface of the material. This method is based on a temporal model of direct and inverse scattering problems for the propagation of transient ultrasonic waves in a homogeneous isotropic slab of porous material with a rigid frame [Fellah et al., J. Acoust. Soc. Am. 113, 61-73 (2003)]. Generally, the conventional ultrasonic approach can be used to determine tortuosity, and viscous and thermal characteristic lengths via transmitted waves. Porosity cannot be estimated in transmitted mode because of its very weak sensitivity. First interface use of the reflected wave at oblique incidence leads to the determination of porosity and tortuosity [Fellah et al., J. Acoust. Soc. Am. 113, 2424-2433 (2003)] but this is not possible at normal incidence. Using experimental data of reflected waves by the first and second interface at normal incidence simultaneously leads to the determination of porosity, tortuosity, viscous and thermal characteristic lengths. As with the classic ultrasonic approach for characterizing porous material saturated with one gas, both characteristic lengths are estimated individually by assuming a given ratio between them. Tests are performed using weakly resistive industrial plastic foams. Experimental and numerical results, and prospects are discussed.

Cytoskeletal 10 nm filaments in cells of the algal phyla Chlorophyta, Charophyta, and Chrysophyta and their developmentally regulated and species-specific association with prosomes

10 nm diameter filaments were observed in whole-mount preparations of algae of diverse phyla: Acetabularia acetabulum and A. major (Chlorophyta), Chara australis and Nitella flexilis (Charophyta), and Poterioochromonas malhamensis (Chrysophyta). A polyclonal antibody raised against a basic, 50 kDa DNA-binding protein of A. acetabulum stains the filaments of A. acetabulumand and A. major as well as of C. australis and N. flexilis. While in the perinuclear region of A. acetabulumand and A. major and throughout the cytoplasm of P. malhamensis the 10 nm filaments have a smooth appearance, in the stalk of A. acetabulumand and A. major they are densely covered by globular structures; in C. australis and N. flexilis they are less frequently associated with such material. The morphology of a part of the globular particles is quite reminiscent of prosomes. A monoclonal antibody elicited against prosomes isolated from A. acetabulum indeed decorates the globular particles on the A. acetabulum and A. major filaments. The possible role of these filament-particle associations is discussed.

Measuring the porosity and the tortuosity of porous materials via reflected waves at oblique incidence

An ultrasonic reflectivity method is proposed for measuring porosity and tortuosity of porous materials having a rigid frame. Porosity is the relative fraction by volume of the air contained within a material. Tortuosity is a geometrical parameter which intervenes in the description of the inertial effects between the fluid filled the porous material and its structure at high frequency range. It is generally easy to evaluate the tortuosity from transmitted waves, this is not the case for porosity because of its weak sensitivity in transmitted mode. The proposed method is based on measurement of reflected wave by the first interface of a slab of rigid porous material. This method is obtained from a temporal model of the direct and inverse scattering problems for the propagation of transient ultrasonic waves in a homogeneous isotropic slab of porous material having a rigid frame [Z. E. A. Fellah, M. Fellah, W. Lauriks, and C. Depollier, J. Acoust. Soc. Am. 113, 61 (2003)]. Reflection and transmission scattering operators for a slab of porous material are derived from the responses of the medium to an incident acoustic pulse at oblique incidence. The porosity and tortuosity are determined simultaneously from the measurements of reflected waves at two oblique incidence angles. Experimental and numerical validation results of this method are presented.

Novel mode of hormone induction of tandem tomato invertase genes in floral tissues

The genomic organization of two extracellular invertase genes from tomato (Lin5 and Lin7), which are linked in a direct tandem repeat, and their tissue-specific and hormone-inducible expression are shown. Transient expression analysis of Lin5 promoter sequences fused to the beta-glucuronidase (GUS) reporter gene (uidA) demonstrates a specific expression of Lin5 during tomato fruit development. A Lin5 promoter fragment was fused to the truncated nos promoter to analyse hormone induction via GUS reporter gene activity in transiently transformed tobacco leaves. A specific up-regulation of GUS activity conferred by this Lin5 promoter fragment in response to gibberellic acid (GA), auxin and abscisic acid (ABA) treatment was observed, indicating a critical role of the regulation of Lin5 by phytohormones in tomato flower and fruit development. In situ hybridization analysis of Lin7 shows a high tissue-specific expression in tapetum and pollen. These results support an important role for Lin5 and Lin7 extracellular invertases in the development of reproductive organs in tomato and contribute to unravel the underlying regulatory mechanisms.

Scanning-force techniques to monitor time-dependent changes in topography and adhesion force of proteins on surfaces

Scanning-force microscopy (SFM) investigations were conducted to probe the influences of the interactions of proteins with surfaces relevant in medicine. These interactions are an important feature in the area of biofilm formation. The adsorption of proteins leads to changes in topography, which was monitored for the build up of protein layers of hen egg-white lysozyme and bovine serum albumin (BSA) on mica in real time in phosphate-buffered aqueous solution over a time period of 10 min. Phase imaging was additionally applied to compare material contrasts and to evaluate this method for further application in this field. The adhesion forces that develop on a time scale below 20 s between a protein-modified SFM tip and titanium surfaces (TiO(2), TiAl6V4 and TiAl6Nb7) were investigated. The influences of the parameters loading force and interaction time between the protein and the surface were monitored as well as the influence of protein structure. The interaction time dependency of the adhesion force could be described with a kinetic model of two consecutive first-order reactions. For the maximal adhesion force a correlation to the ratio of the amino acids cysteine, proline and glycine has been proposed.

Multiparameter single-molecule fluorescence spectroscopy reveals heterogeneity of HIV-1 reverse transcriptase:primer/template complexes

By using single-molecule multiparameter fluorescence detection, fluorescence resonance energy transfer experiments, and newly developed data analysis methods, this study demonstrates directly the existence of three structurally distinct forms of reverse transcriptase (RT):nucleic acid complexes in solution. Single-molecule multiparameter fluorescence detection also provides first information on the structure of a complex not observed by x-ray crystallography. This species did not incorporate nucleotides and is structurally distinct from the other two observed species. We determined that the nucleic acid substrate is bound at a site far removed from the nucleic acid-binding tract observed by crystallography. In contrast, the other two states are identified as being similar to the x-ray crystal structure and represent distinct enzymatically productive stages in DNA polymerization. These species differ by only a 5-A shift in the position of the nucleic acid. Addition of nucleoside triphosphate or of inorganic pyrophosphate allowed us to assign them as the educt and product state in the polymerization reaction cycle; i.e., the educt state is a complex in which the nucleic acid is positioned to allow nucleotide incorporation. The second RT:nucleic acid complex is the product state, which is formed immediately after nucleotide incorporation, but before RT translates to the next nucleotide.

A glutamate mutase is involved in the biosynthesis of the lipopeptide antibiotic friulimicin in Actinoplanes friuliensis

Actinoplanes friuliensis produces the lipopeptide antibiotic friulimicin. This antibiotic is active against gram-positive bacteria such as multiresistant Enterococcus and Staphylococcus strains. It consists of 10 amino acids that form a ring structure and 1 exocyclic amino acid to which an acyl residue is attached. By a reverse genetic approach, biosynthetic genes were identified that are required for the nonribosomal synthesis of the antibiotic. In close proximity two genes (glmA and glmB) were found which are involved in the production of methylaspartate, one of the amino acids of the peptide core. Methylaspartate is synthesized by a glutamate mutase mechanism, which was up to now only described for glutamate fermentation in Clostridium sp. or members of the family ENTEROBACTERIACEAE: The active enzyme consists of two subunits, and the corresponding genes overlap each other. To demonstrate enzyme activity in a heterologous host, it was necessary to genetically fuse glmA and glmB. The resulting gene was overexpressed in Streptomyces lividans, and the fusion protein was purified in an active form. For gene disruption mutagenesis, a host-vector system was established which enables genetic manipulation of Actinoplanes spp. for the first time. Thus, targeted inactivation of biosynthetic genes was possible, and their involvement in friulimicin biosynthesis was demonstrated.

Genetic dissection of gluco- and mineralocorticoid receptor function in mice

Nuclear hormone receptors function to transduce hormonal signals into transcriptional responses by controlling the activity of specific target genes. These target genes comprise a genetic network whose coordinate activity defines the physiological responses to hormonal signals. Dissecting nuclear hormone receptor functions in vivo by gene inactivation and transgenic strategies represents an invaluable and powerful approach to increase our knowledge of these genetic networks and their physiological functions. Glucocorticoids and mineralocorticoids are involved in numerous physiological processes important to maintain metabolic, cardiovascular, central nervous, and immune system homeostasis. Germline and somatic gene targeting as well as an increased dosage of the glucocorticoid receptor (GR) allows the characterization of the various functions and molecular modes of action of this receptor. Most of the effects of the GR are mediated via activation and repression of gene expression. To separate activating from repressing functions of the GR, a point mutation was introduced which allowed us to characterize and distinguish functions dependent on GR binding to DNA from those mediated by protein/protein interaction. Cell/tissue-specific mutations of the gluco- and mineralocorticoid receptor is the basis for the evaluation of their cell-specific functions, including the characterization of target genes of the receptors in order to describe their specific effects on different targets.

[Health - oriented aspects in nutrition of children and adolescents]

The author underlines the necessity of recognition health-oriented aspects in nutrition of children and adolescents for both food producers as well as consumers. It is of great importance not only for growth and development of the young population but also for the health of adults. The author has presented the concept of interrelationship between factors aimed at achieving safe food and proper nutritional guidelines for consumer and the knowledge of genetic and environmental aspects. Educational programmes and research in the field of safe food and proper nutrition sciences should play a crucial role.

The clinical relevance of non-classified dysganglionoses and implications for a new grading system

In addition to the classified types of dysganglionosis, certain non-classified dysganglionoses (NCD) (types 1-4) were introduced by Meier-Ruge in 1992. Clinical data on these conditions are limited. Among 134 children with intestinal dysganglionoses (ID) treated from 1979 to 1999, 12 were identified to have a NCD. Their clinical course is presented. The existence of mild ID (type 1) is difficult to demonstrate. Current definitions and data on clinical relevance are not convincing. An indication for surgical treatment is not present. Isolated hypogenesis of the submucous plexus (SMP) (type 2, n = 8) is clinically a more severe kind of intestinal neuronal dysplasia type B and often requires early surgical intervention, but not resection. When associated with aganglionosis, its recognition is important for surgical strategy, to avoid complicated clinical courses, which are frequent if total or nearly-total resection is not performed. Hypogenesis of the myenteric plexus (MP) (type 5, n = 1) has received little attention so far. The sporadic appearance of heterotopic nerve cells of the SMP in the mucosa (type 3, n = 1) is physiologic; clusters of such cells, however, are probably of pathologic value, especially in combination with other types of ID in the same patient. Heterotopic nerve cells of the MP (type 4, n = 3) in the circular and longitudinal muscle layers are highly pathologic. This clearly-defined type is of major clinical relevance and requires complete resection. A severe disturbance of the migration process is the underlying cause. To simplify the terminology of IDs, a grading system based on the anatomic structures and clinical findings is proposed: innervation disturbances of the mucosa (grade I) are of limited clinical significance. Isolated malformations of the SMP (grade II) may require an enterostomy, but do not require resection except in certain cases associated with distal aganglionosis. Dysganglionosis of the MP (grade III) usually exhibits more severe symptoms and resection is indicated, especially with associated hypo- or aganglionosis. In aganglionic bowel (grade IV) resection is mandatory.