Neutralizing antibodies mediate virus-immune pathology of COVID-19.

SARS-CoV-2 is a novel beta-coronavirus causing over 200.000 lethal cases within six months of first infecting humans. SARS-CoV-2 causes COVID-19, a form of severe acute respiratory syndrome (SARS). COVID-19 is characterized by two phases: the first resembles the flu with pneumonia, but after about seven or eight days the disease suddenly worsens to a sepsis-like syndrome. It is difficult to explain this virus-immune-pathology sequence from virology or immunology only. This paper hypothesizes that host-produced anti-spike protein antibodies are responsible for immune-induced viral dissemination. Subsequently, systemic distribution of virus-antibodies complexes activates the immune pathology observed in severe COVID-19. This hypothesis may be counterintuitive to immunologist that consider many anti-spike antibodies to be virus-neutralizing antibodies. Although anti-spike antibodies may hinder infection of epithelial cells, antibody binding to the spike protein may facilitate virus infection of myeloid leukocytes. If myeloid leukocytes reenter the circulation, they could spread the virus from a locoregional infection to a systemic disease. Disseminated virus in combination with antibodies results in dispersed virus-antibody complexes that overstimulate the immune system. The hypothesis aligns with the sequences of virus, immune and pathological events in COVID-19. The delay in onset from both syndromes results from an immune system still naïve to the non-cross-reactive spike protein. Details of this hypothesis are in concordance with many clinical characteristics of COVID-19, including its predominant lethality for the elderly, and the mostly asymptomatic course of disease in children. It predicts putative detrimental effects of vaccines that induce virus-neutralizing antibodies against the spike protein, as has been shown for other coronaviruses. This hypothesis has consequences for treatment of patients, evaluation of personal and herd immunity and vaccine development. In patients, cellular immunity should be stimulated. Neutralizing antibodies might not be indicative for immunity. Vaccines should aim to stimulate cellular immunity COVID-19 and/or stimulate humoral immunity against viral proteins except for the immunodominant spike protein.

A computerised decision support system for cardiovascular risk management 'live' in the electronic health record environment: development, validation and implementation-the Utrecht Cardiovascular Cohort Initiative.

PURPOSE: We set out to develop a real-time computerised decision support system (CDSS) embedded in the electronic health record (EHR) with information on risk factors, estimated risk, and guideline-based advice on treatment strategy in order to improve adherence to cardiovascular risk management (CVRM) guidelines with the ultimate aim of improving patient healthcare. METHODS: We defined a project plan including the scope and requirements, infrastructure and interface, data quality and study population, validation and evaluation of the CDSS. RESULTS: In collaboration with clinicians, data scientists, epidemiologists, ICT architects, and user experience and interface designers we developed a CDSS that provides 'live' information on CVRM within the environment of the EHR. The CDSS provides information on cardiovascular risk factors (age, sex, medical and family history, smoking, blood pressure, lipids, kidney function, and glucose intolerance measurements), estimated 10-year cardiovascular risk, guideline-compliant suggestions for both pharmacological and non-pharmacological treatment to optimise risk factors, and an estimate on the change in 10-year risk of cardiovascular disease if treatment goals are adhered to. Our pilot study identified a number of issues that needed to be addressed, such as missing data, rules and regulations, privacy, and patient participation. CONCLUSION: Development of a CDSS is complex and requires a multidisciplinary approach. We identified opportunities and challenges in our project developing a CDSS aimed at improving adherence to CVRM guidelines. The regulatory environment, including guidance on scientific evaluation, legislation, and privacy issues needs to evolve within this emerging field of eHealth.

The state of methamphetamine ('tik') use among youth in the Western Cape, South Africa.

BACKGROUND: Methamphetamine use among youth in the Western Cape Province of South Africa has increased at alarming rates over the past decade. Although current estimates of youth use exist, they range from 2 - 12%. OBJECTIVES: To identify (i) the prevalence of methamphetamine use in Western Cape youth and (ii) the association between use and known risk factors for methamphetamine use. METHODS: Data were obtained from 10 000 Western Cape Province Grade 8 learners in 54 secondary schools (mean age 14.0 years). Prevalence was descriptively reported while risk factors for past-month use were modelled in a hierarchical logistic regression with demographic, socioeconomic status, substance use, sexual activity and relationship predictors. RESULTS: Approximately 5% (n=496) of learners had used methamphetamine within their lifetime. Of these users, 65% (n=322) had used in the past month or week. Compared to never users, past-month users were more likely to be male, less likely to have a present or partially present mother, less likely to live in an apartment/flat/brick house, more likely to have used alcohol and tobacco and more likely to report having a same-sex partner. CONCLUSION: Results replicate previously known methamphetamine risk factors and highlight the need to address methamphetamine use in comprehensive prevention initiatives.

Systemic cobalt toxicity from total hip arthroplasties: review of a rare condition Part 1 - history, mechanism, measurements, and pathophysiology.

UNLABELLED: Recently, the use of metal-on-metal articulations in total hip arthroplasty (THA) has led to an increase in adverse events owing to local soft-tissue reactions from metal ions and wear debris. While the majority of these implants perform well, it has been increasingly recognised that a small proportion of patients may develop complications secondary to systemic cobalt toxicity when these implants fail. However, distinguishing true toxicity from benign elevations in cobalt ion levels can be challenging. The purpose of this two part series is to review the use of cobalt alloys in THA and to highlight the following related topics of interest: mechanisms of cobalt ion release and their measurement, definitions of pathological cobalt ion levels, and the pathophysiology, risk factors and treatment of cobalt toxicity. Historically, these metal-on-metal arthroplasties are composed of a chromium-cobalt articulation. The release of cobalt is due to the mechanical and oxidative stresses placed on the prosthetic joint. It exerts its pathological effects through direct cellular toxicity. This manuscript will highlight the pathophysiology of cobalt toxicity in patients with metal-on-metal hip arthroplasties. TAKE HOME MESSAGE: Patients with new or evolving hip symptoms with a prior history of THA warrant orthopaedic surgical evaluation. Increased awareness of the range of systemic symptoms associated with cobalt toxicity, coupled with prompt orthopaedic intervention, may forestall the development of further complications.

Systemic cobalt toxicity from total hip arthroplasties: review of a rare condition Part 2. measurement, risk factors, and step-wise approach to treatment.

UNLABELLED: As adverse events related to metal on metal hip arthroplasty have been better understood, there has been increased interest in toxicity related to the high circulating levels of cobalt ions. However, distinguishing true toxicity from benign elevations in cobalt levels can be challenging. The purpose of this review is to examine the use of cobalt alloys in total hip arthroplasty, to review the methods of measuring circulating cobalt levels, to define a level of cobalt which is considered pathological and to review the pathophysiology, risk factors and treatment of cobalt toxicity. To the best of our knowledge, there are 18 published cases where cobalt metal ion toxicity has been attributed to the use of cobalt-chromium alloys in hip arthroplasty. Of these cases, the great majority reported systemic toxic reactions at serum cobalt levels more than 100 µg/L. This review highlights some of the clinical features of cobalt toxicity, with the goal that early awareness may decrease the risk factors for the development of cobalt toxicity and/or reduce its severity. TAKE HOME MESSAGE: Severe adverse events can arise from the release of cobalt from metal-on-metal arthroplasties, and as such, orthopaedic surgeons should not only be aware of the presenting problems, but also have the knowledge to treat appropriately.

Fretting-corrosion in Hip Implant Modular Junctions: New Experimental Set-up and Initial Outcome.

Modern hip prostheses feature a modular implant design with at least one tapered junction. This design can lead to several complications due to the introduction of additional interfaces, which are subjected to various loading conditions and micromotion. The main objective of current study is to develop a fretting corrosion apparatus, which is able characterize the mechanical and electrochemical behaviour of various existing metal alloy couples during fretting motion. This study describes the design and the main considerations during the development of a novel fretting corrosion apparatus, as well as determination of the machine compliance and the initial testing results. Machine compliance considerations and frictional interactions of the couples are discussed in detail. For the preliminary tests, metal alloy pins, made of Ti6Al4V and wrought high-carbon CoCrMo were mechanically polished to a surface roughness of less than 20nm. 2 pins (Diameter = 11mm) of either Ti6Al4V or CoCrMo were loaded onto a Ti6Al4V alloy rod at a normal force of 200N. The interface types included: Ti6Al4V-Ti6Al4V-Ti6Al4V, Ti6Al4V-Ti6Al4V-CoCrMo, and CoCrMo-Ti6Al4V-CoCrMo. The Ti6Al4V rod articulated against the metal alloy pins in a sinusoidal fretting motion with a displacement amplitude of ±50µm. Bovine calf serum (30g/L of protein content) was selected as a lubricant and tested at 2 different pH levels (pH 3.0 and 7.6). In all cases, current and friction energy were monitored during the fretting process. The results indicated distinct, material-specific current evolutions and friction energies. No significant differences were observed in electrochemical or mechanical behaviour in response to pH change. In general, Ti6Al4V-Ti6Al4V-Ti6Al4V couples displayed the earliest passivation and superior electrochemical behaviour compared to Ti6Al4V-Ti6Al4V-CoCrMo and CoCrMo-Ti6Al4V-CoCrMo under fretting conditions. In addition, fluctuations in current were observed in specific regions at all instances where Ti6Al4V was coupled with Ti6Al4V. These fluctuations were not observed in instances where Ti6Al4V was coupled with CoCrMo. These findings suggest transitions in the degradation mechanisms at the modular junction as a function of material couples/contacts. The findings may assist in improving the current hip modular junctions.

The effect of contact load on CoCrMo wear and the formation and retention of tribofilms.

Tribochemical reactions in a protein lubricated metal-on-metal (MoM) sliding contact may play a significant role for its wear performance. Such reactions lead to the formation of a carbonaceous 'tribofilm', which can act as a protective layer against corrosion and wear. The purpose of this study was to determine the effect of contact load on wear and the formation and retention of tribofilms. Wear tests were performed in a custom-made ball-on-flat testing apparatus that incorporated an electrochemical cell. A ceramic ball was used to articulate against low-carbon wrought CoCrMo alloy pins in bovine serum. Using a range of contact loads at a single potentiostatic condition (close to free potential), weight loss and changes in surface properties were evaluated. We determined that wear was influenced by the loading condition. As expected, wear increased with load, but the association between applied load and measured weight loss was not linear. In the intermediate load region, in the range of 32-48 N (~58-80 MPa), there was more than an order of magnitude drop in the wear per unit load, and the wear versus load data suggested an inflexion point at 49 N. Regression analyses yielded a cubic model (R2=0.991; p=0.0002), where the cubic term, which represents the inflexion, was highly significant (p=0.0021). This model is supported by the observations that the minimum in the friction versus load curve is at 52 N and the highest relative increase in polarization resistance occurred at 49 N. Scanning electron microscopy and Raman spectroscopy indicated the absence of a tribofilm for the low and within the contact area of the high load cases. Synergistic interactions of wear and corrosion seem to play an important role.

What do we know about taper corrosion in total hip arthroplasty?

Mechanically assisted crevice corrosion (MACC) at metal/metal modular junctions in which at least one of the components is fabricated from cobalt-chromium alloy, has reemerged as a potential clinically significant complication in total hip arthroplasty. The clinical manifestation of MACC may include the development of an adverse local tissue reaction (ALTR), similar to what has been described in association with metal-on-metal bearing total hip and resurfacing arthroplasty. The clinical presentation of MACC-associated ALTRs may include pain and possibly late recurrent dislocations. Abnormal metal artifact reduction sequence magnetic resonance images and elevated serum metal levels (cobalt elevations out of proportion to chromium elevations) can be helpful in the diagnosis of these MACC-associated ALTRs.

Tribolayer formation in a metal-on-metal (MoM) hip joint: an electrochemical investigation.

The demand for total hip replacement (THR) surgery is increasing in the younger population due to faster rehabilitation and more complete restoration of function. Up to 2009, metal-on-metal (MoM) hip joint bearings were a popular choice due to their design flexibility, post-operative stability and relatively low wear rates. The main wear mechanisms that occur along the bearing surface of MoM joints are tribochemical reactions that deposit a mixture of wear debris, metal ions and organic matrix of decomposed proteins known as a tribolayer. No in-depth electrochemical studies have been reported on the structure and characteristics of this tribolayer or about the parameters involved in its formation. In this study, we conducted an electrochemical investigation of different surfaces (bulk-like: control, nano-crystalline: new implant and tribolayer surface: retrieved implant) made out of two commonly used hip CoCrMo alloys (high-carbon and low-carbon). As per ASTM standard, cyclic polarization tests and electrochemical impedance spectroscopy tests were conducted. The results obtained from electrochemical parameters for different surfaces clearly indicated a reduction in corrosion for the tribolayer surface (Icorr: 0.76µA/cm(2)). Further, polarization resistance (Rp:2.39±0.60MΩ/cm(2)) and capacitance (Cdl:15.20±0.75µF/cm(2)) indicated variation in corrosion kinetics for the tribolayer surface, that attributed to its structure and stability in a simulated body environment.

Outpatient toxicology clinic experience of patients with hip implants.

CONTEXT: With regard to biological effects, the increasing number of early failure of metal-on-metal (MoM) hip arthroplasties and possible parenteral exposure to orthopedic metal alloys have caused concern for patients and providers alike. OBJECTIVE: We sought to characterize our outpatient clinical experience of patients with MoM and other forms of hip implants and associated serum/blood chromium and cobalt levels, with a focus on possible systemic sequelae. METHODS: This was an observational and retrospective chart review of consecutive patients presenting to two outpatient medical toxicology clinics from January 1, 2010-June 1, 2012 with history of hip implants. Presenting signs, symptoms, and interventions were reviewed. Available cobalt and chromium levels were summarized as median concentration with interquartile range. RESULTS: A total of 39 patients were analyzed; of the 39 patients, 26 had MoM hip implants while 13 did not. Twelve patients exhibited no symptoms and nine sought evaluation for fatigue while two other patients had been previously diagnosed with fibromyalgia. Tinnitus/hearing loss was also a frequent complaint noted in 12 patients (one presenting complaint), however there was no difference between the incidence of this symptom between the MoM and non-MoM groups. Three patients were provisionally diagnosed with demyelinating neuropathy with one patient demonstrating marked (subjective and objective) improvement after revision. Patients with MoM arthroplasties generally exhibit an approximately tenfold increase in metal ion levels than traditional arthroplasties. Finally, 20 (51.2%) patients had replacement or revision of their hip implant with subsequent decreases in metal ion levels. DISCUSSION: A majority of our patients had minor symptoms (fatigue and muscle aches) or no symptoms (n = 23 or 59%). Documented peripheral neurotoxicity is uncommon. The decision for hip revision solely for toxicologic reasons is rare and usually involves a multidisciplinary approach. CONCLUSION: Most patients seeking toxicologic referral may be minimally symptomatic and seek guidance regarding elevated blood or serum metal ions; however, solely toxicologic-based interventions are unusual. Revision was associated with a decrease in metal ion levels; however, subjective complaints did not correlate with metal ion levels.

Prospective study on serum metal levels in patients with metal-on-metal lumbar disc arthroplasty.

PURPOSE: Metal-on-metal total disc replacement is a recent alternative treatment for degenerative disc disease. Wear and corrosion of these implants can lead to local and systemic transport of metal debris. This prospective longitudinal study examined the serum chromium and cobalt levels in 24 patients with cobalt-chromium alloy metal-on-metal lumbar disc replacements. METHODS: Serum was assayed for chromium (Cr) and cobalt (Co) using high-resolution inductively-coupled plasma-mass spectrometry. Detection limits were 0.015 ng/mL for Cr and 0.04 ng/mL for Co. RESULTS: Median serum Co levels at pre-op, 3, 6, 12, 24, and 36-months post-op were 0.10, 1.03, 0.96, 0.98, 0.67, and 0.52 ng/mL, respectively. Median serum Cr levels were 0.06, 0.49, 0.65, 0.43, 0.52, and 0.50 ng/mL, respectively. CONCLUSION: In general, these results indicated that serum Co and Cr levels are elevated at all postoperative time points and are of the same order of magnitude as those observed in well-functioning metal-on-metal surface replacements of the hip and in metal-on-metal total hip replacements at similar postoperative time points.

The Use of Europiumstearate to Trace Polyethylene Wear Debris in Joint Fluid after Prosthetic Joint Replacement - A Feasibility Study.

Ultra-high molecular weight polyethylene (UHMWPE) is the most common counterface material against metals or ceramics in artificial hip or knee joints. Wear and the resulting particulate debris, however, limit the life span of the implant. In this study, the general feasibility of using Europium (Eu) as tracer material to quantify UHMWPE wear in joint fluid is investigated. Using Inductively Coupled Mass Spectrometry (ICP-MS), recovery experiments of Eu in artificial joint fluid were performed. In order to dope polyethylene with 50 ppm Eu, nascent UHMWPE powder was mixed with a solution of Eu-stearate. The heterogeneity of the mixture was assessed by determining the coefficient of variation (CV) of the Eu content in various weighted samples. After molding of the UHMWPE powder mixture, cylindrical pins of 10 mm diameter were machined and worn against cobalt-chromium metal disks submersed in artificial joint fluid. The Eu-content of fluid samples taken at certain time intervals was measured and compared with UHMWPE weight loss of the pins. A satisfactory homogenization of Eu in the UHMWPE powder was achieved. Tracer-based and weight-loss determined wear rates were highly correlated (Pearson correlation coefficients > 0.991). Also the detection bias was within acceptable limits. Thus both methods demonstrated good agreement.

The Hip Society: algorithmic approach to diagnosis and management of metal-on-metal arthroplasty.

Since 1996 more than one million metal-on-metal articulations have been implanted worldwide. Adverse reactions to metal debris are escalating. Here we present an algorithmic approach to patient management. The general approach to all arthroplasty patients returning for follow-up begins with a detailed history, querying for pain, discomfort or compromise of function. Symptomatic patients should be evaluated for intra-articular and extra-articular causes of pain. In large head MoM arthroplasty, aseptic loosening may be the source of pain and is frequently difficult to diagnose. Sepsis should be ruled out as a source of pain. Plain radiographs are evaluated to rule out loosening and osteolysis, and assess component position. Laboratory evaluation commences with erythrocyte sedimentation rate and C-reactive protein, which may be elevated. Serum metal ions should be assessed by an approved facility. Aspiration, with manual cell count and culture/sensitivity should be performed, with cloudy to creamy fluid with predominance of monocytes often indicative of failure. Imaging should include ultrasound or metal artifact reduction sequence MRI, specifically evaluating for fluid collections and/or masses about the hip. If adverse reaction to metal debris is suspected then revision to metal or ceramic-on-polyethylene is indicated and can be successful. Delay may be associated with extensive soft-tissue damage and hence poor clinical outcome.

New insights into hard phases of CoCrMo metal-on-metal hip replacements.

The microstructural and mechanical properties of the hard phases in CoCrMo prosthetic alloys in both cast and wrought conditions were examined using transmission electron microscopy and nanoindentation. Besides the known carbides of M(23)C(6)-type (M=Cr, Mo, Co) and M(6)C-type which are formed by either eutectic solidification or precipitation, a new mixed-phase hard constituent has been found in the cast alloys, which is composed of ∼100 nm fine grains. The nanosized grains were identified to be mostly of M(23)C(6) type using nano-beam precession electron diffraction, and the chemical composition varied from grain to grain being either Cr- or Co-rich. In contrast, the carbides within the wrought alloy having the same M(23)C(6) structure were homogeneous, which can be attributed to the repeated heating and deformation steps. Nanoindentation measurements showed that the hardness of the hard phase mixture in the cast specimen was ∼15.7 GPa, while the M(23)C(6) carbides in the wrought alloy were twice as hard (∼30.7 GPa). The origin of the nanostructured hard phase mixture was found to be related to slow cooling during casting. Mixed hard phases were produced at a cooling rate of 0.2 °C/s, whereas single phase carbides were formed at a cooling rate of 50 °C/s. This is consistent with sluggish kinetics and rationalizes different and partly conflicting microstructural results in the literature, and could be a source of variations in the performance of prosthetic devices in-vivo.

Graphitic tribological layers in metal-on-metal hip replacements.

Arthritis is a leading cause of disability, and when nonoperative methods have failed, a prosthetic implant is a cost-effective and clinically successful treatment. Metal-on-metal replacements are an attractive implant technology, a lower-wear alternative to metal-on-polyethylene devices. Relatively little is known about how sliding occurs in these implants, except that proteins play a critical role and that there is a tribological layer on the metal surface. We report evidence for graphitic material in the tribological layer in metal-on-metal hip replacements retrieved from patients. As graphite is a solid lubricant, its presence helps to explain why these components exhibit low wear and suggests methods of improving their performance; simultaneously, this raises the issue of the physiological effects of graphitic wear debris.

Tribocorrosion behavior of CoCrMo alloy for hip prosthesis as a function of loads: a comparison between two testing systems.

Metal-on-metal (MOM) hip prosthesis bearings have enjoyed renewed popularity, but concerns remain with wear debris and metal ion release causing a negative response in the surrounding tissues. Further understanding into the wear and corrosion mechanisms occurring in MOM hips is therefore essential.The purpose of this study was to evaluate the tribocorrosion behaviour, or interplay between corrosion and wear, of a low-carbon CoCrMo alloy as a function of loading. The tribocorrosion tests were performed using two tribometer configurations. In the first configuration, "System A", a linearly reciprocating alumina ball slid against the flat metal immersed in a phosphate buffer solution (PBS). In the second configuration, "System B", the flat end of a cylindrical metal pin was pressed against an alumina ball that oscillated rotationally, using bovine calf serum (BCS) as the lubricant and electrolyte. System B was custom-built to emulate in vivo conditions. The tribocorrosion tests were performed under potentiostatic conditions at -0.345V, with a sliding duration of 1800 seconds and a frequency of 1Hz. In System A the applied loads were 0.05, 0.5, and 1N (138, 296 and 373MPa, respectively) and in System B were 16, 32, and 64N (474, 597, and 752MPa, respectively). Electrochemical impedance spectroscopy (EIS) and polarization resistance were estimated. The total mass loss (K(wc)) in the CoCrMo was determined. The mass loss due to wear (K(w)) and that due to corrosion (K(c)) were determined. The dominant wear regime for the CoCrMo alloy subjected to sliding changes from wear-corrosion to mechanical wear as the contact stress increases. An attempt was made to compare both system, in their tribochemical responses and formulate some insights in the total degradation processes. Our results also suggest that the proteins in the serum lubricant assist in the generation of a protective layer against corrosion during sliding. The study highlights the need of adequate methodology/guidelines to compare the results from different test systems and translating in solving the practical problems.

Low-dose IL-2 therapy reduces HCV RNA and HBV DNA: case report.

BACKGROUND: Patients with concomitant hepatitis C (HCV) and B (HBV) infection are difficult to treat due to lack of medicines that control these viral infections and the high risk of hepatocellular carcinoma. Currently, there are insufficient data regarding the therapeutic effect of interleukin-2 (IL-2) during chronic viral infection, but this cytokine has shown antineoplastic activity and may have also an antiviral effect. CASE REPORT: We present the case of a 44-year-old patient with hemophilia A, HBV and HCV related compensated liver cirrhosis (Child-Pugh A) with several zones in the liver, highly suspicious for hepatocellular carcinoma. The patient was treated with low-dose intermittent subcutaneous IL-2 immunotherapy, followed by standard therapy with pegasys and copegus. During 23 months' follow-up, no tumour progression occurred, and the patient remained in Child-Pugh A stage. The initial HCV and HBV loads were significant (538,207 IU/ml) and minimal (825 copies/ml), respectively. The patient was treated with intermittent subcutaneously applied low-dose IL-2 cycles for ten months. HBV DNA and HCV RNA were undetectable 3 months after the last IL-2 cycle. After cessation of IL-2 therapy, the patient received standard antiviral treatment with pegasys and copegus. Nine months later, a slight reactivation of viruses was observed: HBV DNA was 18,600 copies/ml and HCV RNA was 58 IU/ml. Twenty-three months after the last IL-2 treatment (at the time of writing), the patient is alive and in a good clinical condition. CONCLUSION: The decrease of HBV and HCV nucleic acids during immunotherapy with IL-2 predicts a possible new therapeutic option for these chronic viral infections.

[Small risk of developing Lyme borreliosis following a tick bite on Ameland: research in a general practice]. / Kleine kans op lymeborreliose na een tekenbeet op Ameland: onderzoek in een huisartsenpraktijk.

OBJECTIVE: To investigate the percentage of ticks infected with Borrelia burgdorferi on the Dutch North Sea island of Ameland, and the risk of developing Lyme disease following tick bite on the island. DESIGN: Prospective, observational. METHOD: Ticks were collected from patients who visited a general practitioner and were tested for the DNA of B. burgdorferi. After 6 months the patients were interviewed by phone using a standardised questionnaire. RESULTS: From 2004-2006, 216 ticks were collected from 167 persons. Most ticks were removed within 24 hours. In 44 ticks (20.4%) B. burgdorferi DNA was detected. Follow up information was available on 146 persons, 41 (28.1%) of whom had been bitten by a Borrelia-positive tick. None of the persons developed a typical erythema migrans. From the 13 persons (9%) reporting a non-specific redness of the skin (diameter less than 5 cm) at the site of the tick bite, 5 had been bitten by a positive tick and 8 by a negative tick. One patient bitten by a positive tick reported systemic symptoms related to Lyme borreliosis, namely fatigue, perspiration and joint ache, without local redness. CONCLUSION: The probability of developing Lyme borreliosis was low even though a relatively large percentage of the ticks collected were positive for B. burgdorferi. This is probably connected to the fact that in the majority of cases the tick had been removed within 24 hours.

In vitro genetic screen identifies a cooperative role for LPA signaling and c-Myc in cell transformation.

c-Myc drives uncontrolled cell proliferation in various human cancers. However, in mouse embryo fibroblasts (MEFs), c-Myc also induces apoptosis by activating the p19Arf tumor suppressor pathway. Tbx2, a transcriptional repressor of p19Arf, can collaborate with c-Myc by suppressing apoptosis. MEFs overexpressing c-Myc and Tbx2 are immortal but not transformed. We have performed an unbiased genetic screen, which identified 12 oncogenes that collaborate with c-Myc and Tbx2 to transform MEFs in vitro. One of them encodes the LPA2 receptor for the lipid growth factor lysophosphatidic acid (LPA). We find that LPA1 and LPA4, but not LPA3, can reproduce the transforming effect of LPA2. Using pharmacological inhibitors, we show that the in vitro cell transformation induced by LPA receptors is dependent on the Gi-linked ERK and PI3K signaling pathways. The transforming ability of LPA1, LPA2 and LPA4 was confirmed by tumor formation assays in vivo and correlated with prolonged ERK1/2 activation in response to LPA. Our results reveal a direct role for LPA receptor signaling in cell transformation and tumorigenesis in conjunction with c-Myc and reduced p19Arf expression.