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The mandible is the only movable bone of the facial bones, and is characterized by a unique anatomical structure and internal structure that provides the function of chewing, swallowing, speaking and it has a complex geometric configuration. The aim of present study was to evaluate topography and geometric shape of acquired mandibular defects and to develop objective diagnostic parameters for their preoperative assessment using multislice computed tomography, computer simulation and 3-D visualization. The material of this study was 60 patients with postoperative and post-traumatic defects of the mandible. To determine the geometric correspondence of defects of the mandible and standard bone autografts from the iliac crest and fibula on standardized mid-anatomical computer models (CAD) of the iliac and fibula bones, by virtual osteotomy, formed 3-D models of autografts to a given volume topographic and anatomical principles of their collection. Then the geometric parameters of the grafts was compared with the parameters of the jaw defects. The achieved shape will only conditionally approach the contour of the mandible, without reproducing its natural curvature. Compensation for these discrepancies is possible through the use of patient-specific anatomical fixators. Our standardized algorithm for determining the geometric parameters of the defect makes the measurement technique reproducible and easy to compare. The obtained values have a specific clinical and biological meaning. Conclusion. One of the possible ways to compensate for geometric inconsistencies is the use of combined patient-specific designs containing elements of the endoprosthesis and individualized fixator. When choosing the optimal type of bone graft, it is necessary to take into account its geometric correspondence of the defect, determined according to our proposed algorithm, as well as biomechanical and biological characteristics of the graft and recipient area.

In patients with severe and recurrent infections, minimal diagnostic workup to test for Inborn Errors of Immunity (IEI) includes a full blood count, IgG, IgA and IgM. Vaccine antibodies against tetanus toxoid are also frequently measured, whereas testing for anti-polysaccharide IgG antibodies and IgG subclasses is not routinely performed by primary care physicians. This basic approach may cause a significant delay in diagnosing monogenic IEI that can present with an impaired IgG response to polysaccharide antigens with or without IgG subclass deficiency at an early stage. Our article reviews genetically defined IEI, that may initially present with an impaired IgG response to polysaccharide antigens, but normal or only slightly decreased IgG levels and normal responses to protein or conjugate vaccine antigens. We summarize clinical, genetic, and immunological findings characteristic for these IEI. This review may help clinicians to identify patients that require extended immunologic and genetic evaluations despite unremarkable basic immunologic findings. We recommend the inclusion of anti-polysaccharide IgG antibodies as part of the initial routine work-up for possible IEI., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision., (© 2024 Fasshauer, Dinges, Staudacher, Völler, Stittrich, von Bernuth, Wahn and Krüger.)

Rationale: Pharmacological improvement of cystic fibrosis transmembrane conductance regulator (CFTR) function with elexacaftor/tezacaftor/ivacaftor (ETI) provides unprecedented improvements in lung function and other clinical outcomes in patients with cystic fibrosis (CF). However, ETI effects on impaired mucosal homeostasis and host defense at the molecular and cellular levels in the airways of patients with CF remain unknown. Objectives: To investigate effects of ETI on the transcriptome of nasal epithelial and immune cells from children with CF at the single-cell level. Methods: Nasal swabs from 13 children with CF and at least one F508del allele aged 6 to 11 years were collected at baseline and 3 months after initiation of ETI, subjected to single-cell RNA sequencing, and compared with swabs from 12 age-matched healthy children. Measurements and Main Results: Proportions of CFTR -positive cells were decreased in epithelial basal, club, and goblet cells, but not in ionocytes, from children with CF at baseline and were restored by ETI therapy to nearly healthy levels. Single-cell transcriptomics revealed an impaired IFN signaling and reduced expression of major histocompatibility complex classes I and II encoding genes in epithelial cells of children with CF at baseline, which was partially restored by ETI. In addition, ETI therapy markedly reduced the inflammatory phenotype of immune cells, particularly of neutrophils and macrophages. Conclusions: Pharmacological improvement of CFTR function improves innate mucosal immunity and reduces immune cell inflammatory responses in the upper airways of children with CF at the single-cell level, highlighting the potential to restore epithelial homeostasis and host defense in CF airways by early initiation of ETI therapy.

Background: Pulmonary manifestations are the major cause of morbidity and mortality in patients with inborn errors of immunity (IEI). New and more sensitive diagnostic methods can potentially lead to earlier recognition and treatment of IEI lung disease and improve outcome. The aim of this study was to compare multiple-breath washout (MBW) and spirometry in patients with IEI and cystic fibrosis (CF) as well as healthy controls (HC) and to evaluate the sensitivity of lung clearance index (LCI) to assess lung disease in IEI., Methods: IEI patients (n=114) were recruited from our paediatric and adult immunodeficiency outpatient clinics and compared to age-matched CF patients (n=114) and HC (n=114). MBW measurements and spirometry were performed in the study participants, and MBW testing was repeated after 63-707 days in IEI patients (n=70)., Results: The LCI was significantly higher in IEI patients than in HC ( p <0.001) and significantly lower than in CF patients (p<0.001). The forced expiratory volume in 1 s (FEV 1 ) z-score was significantly lower in IEI patients than in HC (p<0.01) and significantly higher than in CF patients (p<0.01). LCI and FEV 1 z-score correlated moderately negatively in the total cohort, the IEI group and the CF group. Nineteen (20.7%) of 92 IEI patients and 35 (33.3%) of 105 CF patients had an elevated LCI but a normal FEV 1 z-score. After a median of 364 days, the median LCI of 70 IEI patients increased significantly by 0.2., Conclusion: MBW is useful to detect lung disease in IEI and is more sensitive than spirometry., Competing Interests: Conflict of interest: S. Thee declares grants to their institution from the German Innovation Fond; payment or honoraria from Chiesi (European Cystic Fibrosis Society meeting 2022) and Vertex (LEAD meeting, adherence forum); and travel expenses from Chiesi to attend the European Cystic Fibrosis Society meeting 2022. Conflict of interest: O. Staudacher declares a Travel Grant for Young Immunologists from Arbeitsgemeinschaft Pädiatrische Immunologie in the 36 months prior to manuscript submission. Conflict of interest: E. Steinke declares grants or contracts from the Clinician Scientist Program of the Berlin Institute of Health (funded by the German Federal Ministry of Education and Research); payment or honoraria for review of educational manuscripts from Vertex Pharmaceuticals Inc.; and a travel grant for conference attendance from the European Cystic Fibrosis Society, all in the 36 months prior to manuscript submission. Conflict of interest: J. Röhmel declares payment or honoraria, and support for attending meetings and/or travel from Vertex Pharmaceuticals in the 36 months prior to manuscript submission (with permission from their institution); and an unpaid role as a work package leader in BEAT-PCD, a European Research Society Clinical Research Collaboration. Conflict of interest: V. Wahn declares payment or honoraria from CSL Behring (related to www.immundefekt.de) and Pharming (related to a manuscript on APDS); and an honorarium and travel expenses from Pharming for attendance at the DGKJ congress, all in the 36 months prior to manuscript submission. Conflict of interest: H. von Bernuth declares consulting fees from Infill Healthcare Communication (2022); payment or honoraria from Deutsche Selbsthilfe Angeborene Immundefekte) (2023) and CSL Behring (2021); and payment for expert testimony from Bundessozialgericht (2023); as well as that they are a member of the Standing Comission on Vaccination at the Robert Koch Insitut, Ständige Impfkommission (STIKO). Conflict of interest: M.A. Mall declares funding to their institution in connection to the present work from the German Ministry for Education and Research (BMBF; Grant #82DZL009B1); and an unpaid role as a Fellow of the European Respiratory Society. Conflict of interest: M. Stahl declares funding to their institution (Heisenberg professorship) from the German Research Foundation (Deutsche Forschungsgemeinschaft) in connection to the present work; as well as unpaid roles as Chairman of the Forschungsgemeinschaft Mukoviszidose; Secretary of the Cystic Fibrosis Group of the European Respiratory Society; and Treasurer of the German Society of Paediatric Pulmonology. Conflict of interest: All other authors declare no competing interests., (Copyright ©The authors 2024.)

We describe humans with rare biallelic loss-of-function PTCRA variants impairing pre-α T cell receptor (pre-TCRα) expression. Low circulating naive αβ T cell counts at birth persisted over time, with normal memory αβ and high γδ T cell counts. Their TCRα repertoire was biased, which suggests that noncanonical thymic differentiation pathways can rescue αβ T cell development. Only a minority of these individuals were sick, with infection, lymphoproliferation, and/or autoimmunity. We also report that 1 in 4000 individuals from the Middle East and South Asia are homozygous for a common hypomorphic PTCRA variant. They had normal circulating naive αβ T cell counts but high γδ T cell counts. Although residual pre-TCRα expression drove the differentiation of more αβ T cells, autoimmune conditions were more frequent in these patients compared with the general population.

Background: Assessment of T-cell receptor excision circles (TRECs) in dried blood spots of newborns allows the detection of severe combined immunodeficiency (SCID) (T cells <300/μL at birth) with a presumed sensitivity of 100%. TREC screening also identifies patients with selected combined immunodeficiency (CID) (T cells >300/μL, yet <1500/μL at birth). Nevertheless, relevant CIDs that would benefit from early recognition and curative treatment pass undetected., Objective: We hypothesized that TREC screening at birth cannot identify CIDs that develop with age., Methods: We analyzed the number of TRECs in dried blood spots in archived Guthrie cards of 22 children who had been born in the Berlin-Brandenburg area between January 2006 and November 2018 and who had undergone hematopoietic stem-cell transplantation (HSCT) for inborn errors of immunity., Results: All patients with SCID would have been identified by TREC screening, but only 4 of 6 with CID. One of these patients had immunodeficiency, centromeric instability, and facial anomalies syndrome type 2 (ICF2). Two of 3 patients with ICF whom we have been following up at our institution had TREC numbers above the cutoff value suggestive of SCID at birth. Yet all patients with ICF had a severe clinical course that would have justified earlier HSCT., Conclusions: In ICF, naïve T cells may be present at birth, yet they decline with age. Therefore, TREC screening cannot identify these patients. Early recognition is nevertheless crucial, as patients with ICF benefit from HSCT early in life., (Copyright © 2023 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Recent studies demonstrated that the triple combination cystic fibrosis transmembrane conductance regulator (CFTR) modulator therapy elexacaftor/tezacaftor/ivacaftor (ETI) improves lung function and reduces pulmonary exacerbations in cystic fibrosis (CF) patients with at least one F508del allele. However, effects of ETI on downstream consequences of CFTR dysfunction, i.e. abnormal viscoelastic properties of airway mucus, chronic airway infection and inflammation have not been studied. The aim of this study was to determine the longitudinal effects of ETI on airway mucus rheology, microbiome and inflammation in CF patients with one or two F508del alleles aged ≥12 years throughout the first 12 months of therapy., Methods: In this prospective observational study, we assessed sputum rheology, the microbiome, inflammation markers and proteome before and 1, 3 and 12 months after initiation of ETI., Results: In total, 79 patients with CF and at least one F508del allele and 10 healthy controls were enrolled in this study. ETI improved the elastic modulus and viscous modulus of CF sputum at 3 and 12 months after initiation (all p<0.01). Furthermore, ETI decreased the relative abundance of Pseudomonas aeruginosa in CF sputum at 3 months and increased the microbiome α-diversity at all time points . In addition, ETI reduced interleukin-8 at 3 months (p<0.05) and free neutrophil elastase activity at all time points (all p<0.001), and shifted the CF sputum proteome towards healthy., Conclusions: Our data demonstrate that restoration of CFTR function by ETI improves sputum viscoelastic properties, chronic airway infection and inflammation in CF patients with at least one F508del allele over the first 12 months of therapy; however, levels close to healthy were not reached., Competing Interests: Conflict of interest: J. Röhmel reports payment for presentations at educational events from Vertex Pharmaceuticals, outside the submitted work. D. Lauster has received funding from Deutsche Forschungsgemeinschaft for work related to this manuscript. M. Stahl reports funding from Deutsche Forschungsgemeinschaft related to this manuscript, and grants from Vertex Pharmaceuticals and Mukoviszidose e.V. (German CF Foundation) outside the submitted work, payment for work on an advisory board from Vertex Pharmaceuticals, and is elected, unpaid secretary of the group on paediatric CF of Assembly 7 of the ERS. P. Mertins received funding from Deutsche Forschungsgemeinschaft and the German Federal Ministry of Education and Research related to this work. S.Y. Graeber reports grant support from Mukoviszidose e.V. (German CF Foundation) and Vertex Pharmaceuticals Incorporated outside the submitted work, with payments made to the author's institution. Chiesi GmbH and Vertex Pharmaceuticals Incorporated have provided personal fees for presentations and advisory boards. M.A. Mall declares that he has received funding from Deutsche Forschungsgemeinschaft and German Ministry for Education and Research for work related to this manuscript. In the past 36 months, he has received grants from Vertex Pharmaceuticals, personal fees for consultancy from Boehringer Ingelheim, Arrowhead Pharmaceuticals, Vertex Pharmaceuticals, Santhera, Sterna Biologicals, Enterprise Therapeutics, Antabio and Abbvie, lecture fees from Boehringer Ingelheim, Arrowhead Pharmaceuticals and Vertex Pharmaceuticals, travel reimbursement from Boehringer Ingelheim and Vertex Pharmaceuticals, and personal fees for participation in advisory boards from Boehringer Ingelheim, Arrowhead Pharmaceuticals, Vertex Pharmaceuticals, Santhera, Enterprise Therapeutics, Antabio, Kither Biotech, Abbvie and Pari. Additionally, he served as a member of the Board and Vice-President of the European Cystic Fibrosis Society from 2014 to 2020. All other authors have nothing to disclose., (Copyright ©The authors 2023. For reproduction rights and permissions contact permissions@ersnet.org.)

Competing Interests: Disclosure The authors report no conflicts of interest in this work.

Background: Airway mucus provides important protective functions in health and abnormal viscoelasticity is a hallmark of muco-obstructive lung diseases such as cystic fibrosis (CF). However, previous studies of sputum macrorheology from healthy individuals and patients with CF using different experimental protocols yielded in part discrepant results and data on a systematic assessment across measurement settings and conditions remain limited. Objectives: The aim of this study was to develop an optimized and reliable protocol for standardized macrorheological measurements of airway mucus model systems and native human sputum from healthy individuals and patients with muco-obstructive lung disease. Methods: Oscillatory rheological shear measurements were performed using bovine submaxillary mucin (BSM) at different concentrations (2% and 10% solids) and sputum samples from healthy controls ( n = 10) and patients with CF ( n = 10). Viscoelastic properties were determined by amplitude and frequency sweeps at 25°C and 37°C with or without solvent trap using a cone-plate geometry. Results: Under saturated atmosphere, we did not observe any temperature-dependent differences in 2% and 10% BSM macrorheology, whereas in the absence of evaporation control 10% BSM demonstrated a significantly higher viscoelasticity at 37°C. Similarly, during the measurements without evaporation control at 37°C we observed a substantial increase in the storage modulus G' and the loss modulus G″ of the highly viscoelastic CF sputum but not in the healthy sputum. Conclusion: Our data show systematically higher viscoelasticity of CF compared to healthy sputum at 25°C and 37°C. For measurements at the higher temperature using a solvent trap to prevent evaporation is essential for macrorheological analysis of mucus model systems and native human sputum. Another interesting finding is that the viscoelastic properties are not much sensitive to the applied experimental deformation and yield robust results despite their delicate consistency. The optimized protocol resulting from this work will facilitate standardized quantitative assessment of abnormalities in viscoelastic properties of airway mucus and response to muco-active therapies in patients with CF and other muco-obstructive lung diseases., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Völler, Addante, Rulff, von Lospichl, Gräber, Duerr, Lauster, Haag, Gradzielski and Mall.)

BACKGROUND Large renal tumors during pregnancy are rare findings (0.07-0.1%). Current guidelines recommend surgical removal. This surgery should be carefully planned in an interdisciplinary team and involves special risks for mother and fetus. This report describes a case of a 27-year-old primigravida woman with a right renal cell carcinoma involving the lower pole of the kidney, which was removed at 30 weeks of gestation by robot-assisted retroperitoneoscopic partial nephrectomy (RARPN). CASE REPORT The patient was referred by the treating obstetrician with a newly diagnosed right lower pole renal mass of 6×4 cm in greatest diameter extending deeply into the parenchyma. No metastasis or enlarged lymph nodes were described in subsequent magnetic resonance tomography. Clinical and laboratory examinations documented a healthy mother and fetus. A right-sided RARPN was advised and planned by an interdisciplinary team of treating physicians (gynecologists, oncologists, and urologists). The surgery was conducted under general anesthesia with an obstetrician on stand-by. Surgery was performed without any complications (operation time 95 min, renal-ischemia time 15 min, and negligible blood loss) and histopathology confirmed the diagnosis of a chromophobe renal cell carcinoma. Further follow-up consultations showed regular wound healing and normal progression of pregnancy, and the patient gave birth to a healthy child at term. Follow-up examinations of the patient were uneventful. CONCLUSIONS This case shows that RARPN can be a safe and effective surgical procedure for partial nephrectomy during pregnancy, where surgery is performed in a specialist center and by an interdisciplinary experienced surgical team. It seems to offer advantages and better risk profile over the laparoscopic approach.

In Germany, every year 66,000 road crashes lead to death or injury of young novice drivers. This makes them twice as likely to be involved in, or cause, vehicle crashes compared to their older and more experienced counterparts. This study aims to address this societal issue by developing a better understanding of the German young driver problem. For this purpose, we created an updated, 55-item strong version of the Behaviour of Young Novice Drivers Scale (BYNDS), originally developed by Scott-Parker et al. in 2010. To make the new version of the BYNDS understandable for German young novice drivers, this research used a new method of translation in combination with extensive pre-testing. As a result, we identified possible threats for response errors such as retrospective formulated questions or double negations. Due the adjustment of the possible sources of error the presented version of the BYNDS is semantically and conceptually different from the original. However, due to the application of the updated version of the BYNDS in a robust sample of 700 participants, this paper presents the first reliable and validated tool to measure novices risky driving behaviour in Germany. Moreover, it offers an updated and extended version of the BYNDS that allows practitioners but also researchers to broaden their understanding of young driver risk., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: According to the cancer stem cell hypothesis, tumor growth is sustained by a subpopulation of cancer stem/progenitor-like cells. Self-renewal and high clonogenic potential are characteristics shared by normal stem and neoplastic stem/progenitor-like cells. We investigated whether human prostate cancer specimens contain cells with these properties., Methods: Self-renewal and clonogenic potential were assessed by serial passaging of spheres and colony formation, respectively. Gene expression was analyzed by real time PCR. Protein expression was detected by immunocytochemistry. The neoplastic nature of the cells was verified by detection of the TMPRSS2/ERG gene fusion expression., Results: The epithelial fraction isolated from surgical specimens generated colonies in 68% (19/28) of the patients. Laminin adhesion selected for cells with high clonogenic potential. The epithelial fraction from 85% (42/49) of the patients generated primary prostaspheres. Serial passaging of prostaspheres demonstrated their self-renewal capacity, which is also supported by their expression of the stem cell markers Oct-4, Nanog, Bmi-1, and Jagged-1 mRNA. Cells derived from prostaspheres were more clonogenic than the parental epithelial fraction. The pattern of mRNA expression in prostaspheres resembled that of the basal compartment of the prostate (CK5(+)/CK14(+)/CK19(high)/CK18(-/low)/c-met(+)/AR(-/low)/PSA(-/low)), but also included stem cell markers (CD49b(+)/CD49f(+)/CD44(+)/DeltaNp63(+)/Nestin(+)/CD133(+)). The distribution of marker expression in prostaspheres suggests their heterogeneous cell composition. Prostaspheres expressed significantly higher PSCA mRNA levels than the epithelial fraction., Conclusion: Human prostate cancer specimens contain neoplastic cells with self-renewal and clonogenic potential, which can be enriched and perpetuated in prostaspheres. Prostaspheres should prove valuable for the identification of prostate cancer stem/progenitor-like cells.

The type II 5alpha-reductase inhibitor finasteride is used in the treatment of benign prostatic hyperplasia (BPH), reducing local production of the growth promoting androgen dihydrotestosterone (DHT). The effect of prolonged treatment with this time-dependent irreversible inhibitor on the recently described prostatic type I 5alpha-reductase, however, is not clear. Therefore, we assessed the effects of 5 mg. finasteride per day for 6 months on prostatic 5alpha-reductase isozymes, and prostatic tissue composition and androgen content of patients suffering from BPH. In prostatic tissue from these patients, the type II enzymatic activity is inhibited 100-fold compared with tissues obtained from placebo treated patients. The type II immunoreactivity is up regulated 2-fold. The type I isozyme is inhibited 3-fold and potentially still contributes to DHT production. In conclusion, finasteride is a selective type II inhibitor in vivo. Further research is warranted to assess the possibly distinct roles of the 5alpha-reductase isozymes in the normal prostate, in BPH, and during finasteride treatment.

Recently we described a protein, smoothelin, that has been exclusively found in smooth muscle cells (SMC). The human cDNA has been cloned from a colon cDNA library and the putative protein sequence was deduced. Smoothelin does not belong to a known protein family but shows a partial homology with members of the spectrin family. Transfection studies revealed that smoothelin has an affinity for actin and is either capable of forming filamentous structures or colocalizes with such structures. The protein is expressed in visceral as well as vascular tissues of all vertebrate classes. A study on the distribution of smoothelin in the vascular and placental system showed that smoothelin expression was largely restricted to the muscular pulsating blood vessels. Therefore, we hypothesized that smoothelin is expressed in contractile SMC only (36, 37). No expression of smoothelin was observed in established cell lines of SMC. In tissue explants smoothelin mRNA concentration decreases to undetectable levels within 12 hours after dissection as was in general the case in primary cell cultures. Here we report on continued smoothelin expression for several passages observed in a human prostate primary cell culture system. Smoothelin was demonstrated to colocalize with actin stress fibers but not with desmin filaments. This culture system offers opportunities to study the cytological localization of smoothelin, interactions with other proteins and should provide a system to test the promoter of the smoothelin gene. On immunoblots the molecular weight of smoothelin differed between visceral and vascular smooth muscle tissue with apparent molecular weights of respectively 59 kDa and 94 kDa. There is no evidence for the existence of another gene coding for the 94 kDa smoothelin. Thus, posttranslational modification, alternative splicing and dual promoter control are the alternatives for the expression of two isoforms of smoothelin.

Cadherins constitute a gene family of Ca(2+)-dependent cell-cell adhesion molecules involved in the morphogenesis and maintenance of tissue integrity. E- and P-cadherin are members of the cadherin family that are both expressed in epithelial tissues. Here we present the localization of the human P-cadherin gene at 32 kb upstream of the human E-cadherin gene, mapping it to chromosome 16q22.1. Tandem arrangement of two cell-cell adhesion molecules from the cadherin family has also been reported in chicken. This is the first evidence for the direct linkage of two cadherins in mammals. The evolutionary conservation of the tandem arrangement of two genes encoding cell adhesion molecules suggests that the close proximity of the genes may be important for the regulation of the genes.

In normal rat kidney cells protein tyrosine phosphatases (PTPases) play a role in attaining density-dependent growth arrest after stimulation with mitogens. The PTPase inhibitor sodium orthovanadate prevents density-dependent growth inhibition of EGF-treated cells and mimicks in that respect the action of TGF beta and retinoic acid. However, enhanced PTPase activity is not obligatory for maintaining cells in a density-arrested state. In contrast to TGF beta and retinoic acid, vanadate is unable to restimulate density-inhibited cells, indicating that different mechanisms are operating. Yet, vanadate is strongly potentiating the effect of low concentrations of TGF beta but not of retinoic acid, implicating that tyrosine phosphorylation is linked to TGF beta action and that PTPase may represent a negative control element in the TGF beta signaling pathway.

Normal rat kidney [NRK] cells grown in the presence of epidermal growth factor (EGF) or platelet-derived growth factor (PDGF) have a normal phenotype and undergo density-dependent growth inhibition, whereas in the presence of multiple growth factors, density arrest is lost and the cells become phenotypically transformed. We studied the influence of the protein tyrosine phosphatase (PTPase) inhibitor sodium orthovanadate on the mitogenic stimulation of NRK cells by growth factors and on transformation-linked properties as loss of density-dependent growth inhibition and anchorage-independent growth. The fraction of cells in serum-deprived monolayer cultures that is induced to proliferate upon mitogenic stimulation by EGF or PDGF is only slightly enhanced upon addition of low concentrations (25-50 microM) of vanadate. Addition of vanadate per se induces proliferation of only a very limited amount of cells, but results in a shift of the dose-response curves for other growth factors to lower concentrations. Vanadate added in combination with EGF or PDGF is able to mimic the effect of transforming growth factor beta (TGF beta) in inducing phenotypic transformation. In monolayer cultures density-dependent growth inhibition is lost and anchorage-independent proliferation is observed on dishes coated with poly(2-hydroxy-ethyl methacrylate) (polyHEMA). The extent of these changes is similar to that induced by TGF beta. However, the morphology of the obtained colonies in polyHEMA-coated dishes is quite different. Cells transformed by TGF beta in the presence of EGF form rather amorphous colonies, whereas in the presence of orthovanadate colonies are formed that tend to fall apart in loose cells. The effect of vanadate on cell transformation is dependent on the growth factor conditions in a bimodal way. When a suboptimal dose of growth factor(s) is used, 25 microM vanadate is very effective in preventing density-induced growth inhibition and stimulating anchorage-independent proliferation. However, the same concentration of vanadate is inhibitory when cells are maximally stimulated and antagonizes the transforming effect of TGF beta added in combination with other growth factors. It is hypothesized that vanadate acts on a set of different protein tyrosine phosphatases. Some of these are positive and others negative regulators of growth.