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1.
BMJ Open ; 13(5): e070475, 2023 05 09.
Article in English | MEDLINE | ID: mdl-37160385

ABSTRACT

OBJECTIVES: In order to reduce the use of emergency departments, computer-assisted initial assessment was implemented at the medical on-call service 116117. Our study assessed compliance and patient satisfaction. DESIGN: Cross-sectional observational postal survey. SETTING: Medical on-call service 116117 by eight Associations of Statutory Health Insurance Physicians in Germany. PARTICIPANTS: The intervention was observed between January 2020 and March 2021. Minors and patients with invalid contact data were excluded. A random sample of eligible patients received standardised questionnaires by mail. OUTCOME MEASURES: We analysed associations of sociodemographic data, health status, previous service use, health literacy, and recommended settings with compliance and patient satisfaction by multivariable, multilevel logistic regression. INTERVENTIONS: Based on symptoms and context factors, the computer software suggested service levels. Staff and patient discussed if higher levels were indicated, services were available and self-transport was possible. They then agreed on recommendations for treatment settings. RESULTS: Of 9473 contacted eligible patients, 1756 patients (18.5%) participated. Median age was 66 years (IQR=50-79), and 986 (59.0%) were women. At least one recommended setting was used by 1397 patients (85.4%). General practitioner (GP) practices were used by 143 patients (68.4%). Generally, better compliance was associated with lower depression levels (OR 1.59, 95% CI 1.17 to 2.17, p=0.003), fewer previous hospital stays (OR 2.02, 95% CI 1.27 to 3.23, p=0.003) and recommendations for any setting other than GP practices (OR 0.13, 95% CI 0.06 to 0.29, p<0001, to OR 0.37, 95% CI 0.19 to 0.72, p=0.003). A total of 606 patients (50.7%) were completely satisfied. Patient satisfaction was associated with higher age (OR 1.30, 95% CI 1.13 to 1.49, p<0.001), better self-rated health (OR 1.30, 95% CI 1.10 to 1.53, p=0.002), not having musculoskeletal disorders (OR 0.68, 95% CI 0.49 to 0.94, p=0.021), better health literacy (OR 0.69, 95% CI 0.54 to 0.89, p=0.005, and OR 0.49, 95% CI 0.36 to 0.67, p<0.001) and receiving no recommendation for GP practices (OR 0.61, 95% CI 0.43 to 0.87, p=0.006). CONCLUSIONS: Most patients were compliant and satisfied. Lowest compliance and satisfaction were found in GP practices, but nonetheless, two of three patients with respective recommendations were willing to use this setting. TRIAL REGISTRATION NUMBER: German Clinical Trials Register DRKS00017014.


Subject(s)
General Practitioners , Patient Satisfaction , Humans , Female , Aged , Male , Cross-Sectional Studies , Germany , Computers
2.
JAMA Netw Open ; 6(3): e234732, 2023 03 01.
Article in English | MEDLINE | ID: mdl-36972051

ABSTRACT

Importance: Uptake of vaccination against COVID-19 is strongly affected by concerns about adverse effects. Research on nocebo effects suggests that these concerns can amplify symptom burden. Objective: To investigate whether positive and negative expectations prior to COVID-19 vaccination are associated with systemic adverse effects. Design, Setting, and Participants: This prospective cohort study analyzed the association of expected benefits and risks of vaccination, adverse effects at first vaccination, and observed adverse effects in close contacts with severity of systemic adverse effects among adults receiving a second dose of messenger RNA (mRNA)-based vaccines between August 16 and 28, 2021. A total of 7771 individuals receiving the second dose at a state vaccination center in Hamburg, Germany, were invited to participate; of these, 5370 did not respond, 535 provided incomplete information, and 188 were excluded retrospectively. The mobile application m-Path was used for data collection. Main Outcomes and Measures: Primary outcome was a composite severity index of systemic adverse effects in 12 symptom areas measured once daily with an electronic symptom diary over 7 consecutive days. Data were analyzed by mixed-effects multivariable ordered logistic regression adjusted for prevaccine symptom levels and observation times. Results: A total of 10 447 observations from 1678 individuals receiving vaccinations (BNT162b2 [Pfizer BioNTech] in 1297 [77.3%] and mRNA-1273 [Moderna] in 381 [22.7%]) were collected. The participants' median age was 34 (IQR, 27-44) years, and 862 (51.4%) were women. The risk for more severe adverse effects was higher for persons expecting a lower benefit of vaccination (odds ratio [OR] for higher expectations, 0.72 [95% CI, 0.63-0.83]; P < .001), expecting higher adverse effects of vaccination (OR, 1.39 [95% CI, 1.23-1.58]; P < .001), having experienced higher symptom burden at the first vaccination (OR, 1.60 [95% CI, 1.42-1.82]; P < .001), scoring higher on the Somatosensory Amplification Scale (OR, 1.21 [95% CI, 1.06-1.38]; P = .004), and if the vaccine mRNA-1273 was given rather than BNT162b2 (OR, 2.45 [95% CI, 2.01-2.99]; P < .001). No associations were seen for observed experiences. Conclusions and Relevance: In this cohort study, several nocebo effects occurred in the first week after COVID-19 vaccination. The severity of systemic adverse effects was associated not only with vaccine-specific reactogenicity but also more negative prior experiences with adverse effects from the first COVID-19 vaccination, more negative expectations regarding vaccination, and tendency to catastrophize instead of normalize benign bodily sensations. Clinician-patient interactions and public vaccine campaigns may both benefit from these insights by optimizing and contextualizing information provided about COVID-19 vaccines.


Subject(s)
COVID-19 Vaccines , COVID-19 , Drug-Related Side Effects and Adverse Reactions , Adult , Female , Humans , Male , 2019-nCoV Vaccine mRNA-1273 , BNT162 Vaccine , Cohort Studies , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , Motivation , Prospective Studies , Vaccination/adverse effects
3.
BMC Prim Care ; 23(1): 213, 2022 08 23.
Article in English | MEDLINE | ID: mdl-35999511

ABSTRACT

BACKGROUND: Patient numbers in emergency departments are on the rise. The DEMAND intervention aims to improve the efficacy of emergency services by computer-assisted structured initial assessment assigning patients to emergency departments or primary care practices. The aims of our study were to evaluate patient satisfaction with this intervention and to analyse if reduced patient satisfaction is predicted by sociodemographic data, health status or health literacy. METHODS: We conducted a cross-sectional patient survey in emergency departments and co-located primary care practices. Each intervention site was planned to participate for two observation periods, each with a duration of one full week. Study participants were recruited by the local staff. The patients filled out a written questionnaire during their waiting time. Patient satisfaction was assessed by agreement to four statements on a four point Likert scale. Predictors of patient satisfaction were identified by multilevel, multivariable logistic regression models adjusted for random effects at the intervention site level. RESULTS: The sample included 677 patients from 10 intervention sites. The patients had a mean age of 38.9 years and 59.0% were women. Between 67.5% and 55.0% were fully satisfied with aspects of the intervention. The most criticised aspect was that the staff showed too little interest in the patients' personal situation. Full satisfaction ("clearly yes" to all items) was reported by 44.2%. Reduced patient satisfaction (at least one item rated as "rather yes", "rather no", "clearly no") was predicted by lower age (odds ratio 0.79 for ten years difference, 95% confidence interval 0.67/0.95, p = 0.009), presenting with infections (3.08,1.18/8.05,p = 0.022) or injuries (3.46,1.01/11.82,p = 0.048), a higher natural logarithm of the symptom duration (1.23,1.07/1.30,p = 0.003) and a lower health literacy (0.71 for four points difference, 0.53/0.94,p = 0.019). CONCLUSIONS: The patients were for the most part satisfied with the intervention. Assessment procedures should be evaluated a) regarding if all relevant patient-related aspects are included; and whether patient information can be improved b) for patients with strong opinions about cause, consequences and treatment options for their health problem; and c) for patients who have problems in the handling of information relevant to health and healthcare. TRIAL REGISTRATION: German Clinical Trials Register ( https://www.drks.de/drks_web/setLocale_EN.do ) no. DRKS00017014.


Subject(s)
Emergency Service, Hospital , Patient Satisfaction , Adult , Child , Computers , Cross-Sectional Studies , Female , Germany , Humans , Male , Primary Health Care
4.
ZFA (Stuttgart) ; 98(4): 126-132, 2022.
Article in German | MEDLINE | ID: mdl-37273520

ABSTRACT

Background: Sore throat is a common reason for consultation of family physicians. Acute sore throat (< 14 days) is usually triggered by infections of the pharynx. Less than 35 % of cases are caused by bacterial infections; nevertheless, antibiotics are prescribed far more often. Evidence-based guideline recommendations are available to reduce non-indicated administration of antibiotics in the treatment of sore throat. Search Methods: Update of the clinical guideline "sore throat" of the German College of General Practitioners and Family Physicians (DEGAM) by means of a systematic search of the literature for international guidelines and systematic reviews. Main Messages: After excluding red flags such as immunosuppression and severe systemic infections, acute sore throat is usually self-limiting with a mean duration of 7 days. Patients should be encouraged in self-management; ibuprofen and naproxen are recommended for symptomatic treatment. If antibiotics are considered, clinical scores (Centor, McIsaac, FeverPAIN) should be used to assess the risk of bacterial pharyngitis. At low risk (< 3 points), antibiotics are not indicated; if at least moderate (3 points), delayed prescription is an option; if high (> 3 points), antibiotics can be taken immediately. Even if scores suggestive a bacterial cause, the evidence suggests that antibiotic treatment only shortens the duration of symptoms modestly. Penicillin is the first choice (clarithromycin as an alternative). The antibiotic should be taken for 5-7 days. Conclusions: In the absence of red flags, a regular use of symptomatic treatment will help to control discomfort. If administration of antibiotics is still considered a risk-adapted approach, using clinical scores is recommended.

5.
BMJ Open ; 11(11): e053110, 2021 11 24.
Article in English | MEDLINE | ID: mdl-34819288

ABSTRACT

OBJECTIVES: Aim of this study was to analyse if subjectively perceived treatment urgency of patients in emergency departments is associated with self-reported health literacy and the willingness to use the general practitioner (GP) as coordinator of treatment. DESIGN: A multicentre, cross-sectional, observational study. SETTING: Emergency departments in five hospitals. Each hospital was visited 14 times representing two 8-hour shifts on each day of the week. Calendar dates were randomly assigned. PARTICIPANTS: All patients of legal age registered at the emergency department or hospital reception desk. Exclusion criteria included immediate or very urgent need of treatment, high level of symptom burden and severe functional impairments in terms of hearing, vision and speech. We conducted standardised personal interviews. Additionally, clinical data were extracted from patient records. PRIMARY AND SECONDARY OUTCOME MEASURES: Our target variable was subjectively perceived treatment urgency. Predictor variables included age, sex, education, health-related quality of life (EuroQol Five-Dimension Scale, value set UK), anxiety and depression (Hospital Anxiety and Depression Scale), somatic symptoms (Patient Health Questionnaire, 15 items version), self-reported health literacy (European Health Literacy Questionnaire, 16 questions version) and the commitment to the GP (Fragebogen zur Intensität der Hausarztbindung, 'F-HaBi'). Data were analysed by multilevel, multivariable linear regression adjusted for random effects at the hospital level. RESULTS: Our sample comprised 276 patients with a mean age of 50.1 years and 51.8% women. A low treatment urgency (defined as 0-5 points on a Numerical Rating Scale) was reported by 111 patients (40.2%). In the final model, lower subjective treatment urgency was associated with male sex (ß=0.84; 95% CI 0.11/1.57, p=0.024), higher health-related quality of life (-2.27 to -3.39/-1.15, p<0.001), lower somatic symptoms score (0.09, 0.004/0.17, p=0.040), higher anxiety score (-0.13 to -0.24/-0.01, p=0.027) and lower commitment to the GP (0.08, 0.01/0.14, p=0.029). CONCLUSIONS: A lower level of subjectively perceived treatment urgency was predicted by a lower willingness to use the GP as coordinator of treatment. Self-reported health literacy did not predict the patients' urgency rating.


Subject(s)
General Practitioners , Health Literacy , Cross-Sectional Studies , Emergency Service, Hospital , Female , Humans , Male , Middle Aged , Quality of Life , Self Report
6.
Dtsch Arztebl Int ; 118(31-32): 542-543, 2021 08 09.
Article in English | MEDLINE | ID: mdl-34612197
7.
Dtsch Arztebl Int ; 118(11): 188-94, 2021 03 19.
Article in English | MEDLINE | ID: mdl-33602392

ABSTRACT

BACKGROUND: Sore throat is a common reason for consultation of primary care physicians, pediatricians, and ENT specialists. The updated German clinical practice guideline on sore throat provides evidence-based recommendations for treatment in the German healthcare system. METHODS: Guideline revision by means of a systematic search of the literature for international guidelines and systematic reviews. All recommendations resulted from interdisciplinary cooperation and were agreed by formal consensus. The updated guideline applies to patients aged 3 years and over. RESULTS: In the absence of red flags such as immunosuppression, severe comorbidity, or severe systemic infection, acute sore throat is predominantly self-limiting. The mean duration is 7 days. Chronic sore throat usually has noninfectious causes. Laboratory tests are not routinely necessary. Apart from non-pharmacological self-management, ibuprofen and naproxen are recommended for symptomatic treatment. Scores can be used to assess the risk of bacterial pharyngitis: one point each is assigned for tonsil lesions, palpable cervical lymph nodes, patient age, disease course, and elevated temperature. If the risk is low (<3 points), antibiotics are not indicated; if at least moderate (3 points), delayed prescribing is recommended; if high (>3 points), antibiotics can be taken immediately. Penicillin remains the first choice, with clarithromycin as an alternative for those who do not tolerate penicillin. The antibiotic should be taken for 5-7 days. CONCLUSION: After the exclusion of red flags, antibiotic treatment is unnecessary in many cases of acute sore throat. If administration of antibiotics is still considered in spite of consultation on the usual course of tonsillopharyngitis and the low risk of complications, a risk-adapted approach using clinical scores is recommended.


Subject(s)
Pharyngitis , Anti-Bacterial Agents/therapeutic use , Fever/drug therapy , Humans , Pain , Penicillins/therapeutic use , Pharyngitis/diagnosis , Pharyngitis/etiology , Pharyngitis/therapy
8.
BMJ Open ; 10(10): e035625, 2020 10 22.
Article in English | MEDLINE | ID: mdl-33093028

ABSTRACT

OBJECTIVES: The aims of our study were to describe the disease spectrum of refugees, to analyse to what extent their healthcare needs could be met in an outpatient primary care walk-in clinic and which cases required additional services from secondary care (ie, outpatient specialists or hospitals). DESIGN: Retrospective longitudinal observational study. SETTING: The study was based on routine data from a walk-in clinic in the largest central first reception centre in Hamburg, Germany between 4 November 2015 and 21 July 2016. PARTICIPANTS: 1467 asylum seekers with 4006 episodes of care (ie, distinctive health problems) resulting in 5545 consultations. The patients were 60% men and had a mean age of 23.2 years. About 90% of the patients were from Central Asia or from the Middle East and North Africa. PRIMARY AND SECONDARY OUTCOME MEASURES: The endpoint of our analyses was referral to secondary care. Time to event was defined as days under treatment until the first referral. Predictor variables were the patients' diagnoses grouped in 46 categories. The data set was analysed by Cox regression allowing for multiple failure times per patient. This analysis was adjusted for age, sex and country of origin. RESULTS: Referrals to secondary care occurred in 15.5% of the episodes. The diagnosis groups with the highest referral rates were 'eye' (HR 4.9; 95% CI 3.12 to 7.8; p≤0.001), 'teeth/gum symptom/complaint or disease' (3.51; 2.52 to 4.9; p≤0.001) and 'urological system/female or male genital' (2.50; 1.66 to 3.77; p≤0.001). Age, sex and country of origin had no significant effect on time until referral. CONCLUSIONS: In most cases, the walk-in clinic physicians could provide first-line medical care for the health problems of patients not integrated in the German healthcare system. Additional resources were needed particularly not only for visual impairment and dental problems but also for psychological disorders, antenatal care and certain infections and injuries.


Subject(s)
Refugees , Adult , Africa, Northern , Data Analysis , Electronic Health Records , Female , Germany , Humans , Male , Middle East , Outpatients , Pregnancy , Primary Health Care , Referral and Consultation , Retrospective Studies , Secondary Care , Young Adult
9.
BMC Fam Pract ; 21(1): 193, 2020 09 21.
Article in English | MEDLINE | ID: mdl-32958030

ABSTRACT

BACKGROUND: From 2015 to 2016 Germany faced an influx of 1.16 million asylum seekers. In the state of Hamburg Primary Care walk-in clinics (PCWC) were commissioned at refugee camps because the high number of residents (57,000 individuals) could not be provided with access to regular healthcare services. Our study aims were (1) to describe the utilization of a PCWC by camp residents, (2) to compare episodes of continuous care with shorter care episodes and (3) to analyse which diagnoses predict episodes of continuous care in this setting. METHODS: A retrospective longitudinal observational study was conducted by reviewing all anonymized electronic medical records of a PCWC that operated from 4th November 2015 to 22nd July 2016 at a refugee camp in Hamburg. Episodes of care (EOC) were extracted based on the international classification of primary care-2nd edition (ICPC-2). Outcome parameters were episode duration, principal diagnoses, and medical procedures. RESULTS: We analysed 5547 consultations of 1467 patients and extracted 4006 EOC. Mean patient age was 22.7 ± 14.8 years, 37.3% were female. Most common diagnoses were infections (44.7%), non-communicable diseases (22.2%), non-definitive diagnoses describing symptoms (22.0%), and injuries (5.7%). Most patients (52.4%) had only single encounters, whereas 19.8% had at least one EOC with a duration of ≥ 28 days (defined as continuous care). Several procedures were more prevalent in EOC with continuous care: Blood tests (5.2 times higher), administrative procedures (4.3), imaging (3.1) and referrals to secondary care providers (3.0). Twenty prevalent ICPC-2-diagnosis groups were associated with continuous care. The strongest associations were endocrine/metabolic system and nutritional disorders (hazard ratio 5.538, p < 0.001), dermatitis/atopic eczema (4.279, p < 0.001) and psychological disorders (4.056, p < 0.001). CONCLUSION: A wide spectrum of acute and chronic health conditions could be treated at a GP-led PCWC with few referrals or use of medical resources. But we also observed episodes of continuous care with more use of medical resources and referrals. Therefore, we conclude that principles of primary care like continuity of care, coordination of care and management of symptomatic complaints could complement future healthcare concepts for refugee camps.


Subject(s)
Refugee Camps , Refugees , Data Analysis , Episode of Care , Female , Germany , Humans , Primary Health Care , Retrospective Studies
10.
Article in German | MEDLINE | ID: mdl-31428831

ABSTRACT

BACKGROUND: The number of patients in emergency rooms without a medical emergency is increasing. Outpatient services for mutual support and relief between the in-patient and out-patient sector are not yet fully established. AIM OF THE WORK: The aim was to determine the extent to which patients in emergency rooms have real medical emergencies by comparing patients with at least two and those with a maximum of one chronic illness. An additional aim was to identify factors influencing the previous use of outpatient structures. MATERIAL AND METHODS: The study participants included emergency room patients from the cross-sectional study "PiNo-Nord." All persons in five emergency rooms in northern Germany between October 2015 and July 2016 who were not treated as "immediate" or "very urgent" were interviewed. An exploratory data analysis and multivariate logistic regression were performed. RESULTS: The 293 patients with ≥2 chronic diseases were just as often a medical emergency compared to the 847 patients with a maximum of 1 chronic disease. The most frequent occasions for consultation were musculoskeletal trauma (33%, n = 293 vs. 42%, n = 847) or trauma of the skin (11%, n = 293 vs. 13%, n = 847). In both groups, the general practitioner or specialist caregiver, as well as diagnostic or treatment options, rarely played a role in visiting the emergency department. The strongest predictors of previous outpatient treatment were the duration of the appeal in the last six months, a high subjective treatment urgency, the presence of at least two chronic conditions, and a consultation event concerning the musculoskeletal injuries. CONCLUSIONS: In both patient groups, no evidence of unnecessary visits to the emergency room was found. For the most part, outpatient structures are used in advance and the emergency department is only visited in the event of an actual medical emergency.


Subject(s)
Chronic Disease/therapy , Emergency Service, Hospital/statistics & numerical data , Patient Discharge , Chronic Disease/epidemiology , Cross-Sectional Studies , Germany , Humans , Referral and Consultation
11.
Trials ; 19(1): 480, 2018 Sep 10.
Article in English | MEDLINE | ID: mdl-30201053

ABSTRACT

BACKGROUND: Traumatic events like critical illness and intensive care are threats to life and bodily integrity and pose a risk factor for posttraumatic stress disorder (PTSD). PTSD affects the quality of life and morbidity and may increase health-care costs. Limited access to specialist care results in PTSD patients being treated in primary care settings. Narrative exposure therapy (NET) is based on the principles of cognitive behavioral therapy and has shown positive effects when delivered by health-care professionals other than psychologists. The primary aims of the PICTURE trial (from "PTSD after ICU survival") are to investigate the effectiveness and applicability of NET adapted for primary care with case management in adults diagnosed with PTSD after intensive care. METHODS/DESIGN: This is an investigator-initiated, multi-center, primary care-based, randomized controlled two-arm parallel group, observer-blinded superiority trial conducted throughout Germany. In total, 340 adult patients with a total score of at least 20 points on the posttraumatic diagnostic scale (PDS-5) 3 months after receiving intensive care treatment will be equally randomized to two groups: NET combined with case management and improved treatment as usual (iTAU). All primary care physicians (PCPs) involved will be instructed in the diagnosis and treatment of PTSD according to current German guidelines. PCPs in the iTAU group will deliver usual care during three consultations. In the experimental group, PCPs will additionally be trained to deliver an adapted version of NET (three sessions) supported by phone-based case management by a medical assistant. At 6 and 12 months after randomization, structured blinded telephone interviews will assess patient-reported outcomes. The primary composite endpoint is the absolute change from baseline at month 6 in PTSD symptom severity measured by the PDS-5 total score, which also incorporates the death of any study patients. Secondary outcomes cover the domains depression, anxiety, disability, health-related quality-of-life, and cost-effectiveness. The principal analysis is by intention to treat. DISCUSSION: If the superiority of the experimental intervention over usual care can be demonstrated, the combination of brief NET and case management could be a treatment option to relieve PTSD-related symptoms and to improve primary care after intensive care. TRIAL REGISTRATION: ClinicalTrials.gov, NCT03315390 . Registered on 10 October 2017. German Clinical Trials Register, DRKS00012589 . Registered on 17 October 2017.


Subject(s)
Case Management , Critical Care/methods , Narrative Therapy/methods , Primary Health Care/methods , Stress Disorders, Post-Traumatic/therapy , Critical Care/psychology , Germany , Humans , Multicenter Studies as Topic , Randomized Controlled Trials as Topic , Severity of Illness Index , Stress Disorders, Post-Traumatic/diagnosis , Stress Disorders, Post-Traumatic/psychology , Time Factors , Treatment Outcome
12.
EMBO Mol Med ; 4(6): 486-99, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22488882

ABSTRACT

'Tomacula' and myelin outfoldings are striking neuropathological features of a diverse group of inherited demyelinating neuropathies. Whereas the underlying genetic defects are well known, the molecular mechanisms of tomacula formation have remained obscure. We hypothesized that they are caused by uncontrolled, excessive myelin membrane growth, a process, which is regulated in normal development by neuregulin-1/ErbB2, PI3 Kinase signalling and ERK/MAPK signalling. Here, we demonstrate by targeted disruption of Pten in Schwann cells that hyperactivation of the endogenous PI3 Kinase pathway causes focal hypermyelination, myelin outfoldings and tomacula, even when induced in adult animals by tamoxifen, and is associated with progressive peripheral neuropathy. Activated AKT kinase is associated with PtdIns(3,4,5)P(3) at paranodal loops and Schmidt-Lanterman incisures. This striking myelin pathology, with features of human CMT type 4B1 and HNPP, is dependent on AKT/mTOR signalling, as evidenced by a significant amelioration of the pathology in mice treated with rapamycin. We suggest that regions of non-compact myelin are under lifelong protection by PTEN against abnormal membrane outgrowth, and that dysregulated phosphoinositide levels play a critical role in the pathology of tomaculous neuropathies.


Subject(s)
Arthrogryposis/pathology , Gene Knockout Techniques , Hereditary Sensory and Motor Neuropathy/pathology , Myelin Sheath/pathology , PTEN Phosphohydrolase/deficiency , Animals , Cell Line , Disease Models, Animal , Mice , Schwann Cells/chemistry , Schwann Cells/cytology
13.
J Neurosci ; 30(26): 8953-64, 2010 Jun 30.
Article in English | MEDLINE | ID: mdl-20592216

ABSTRACT

In the developing nervous system, constitutive activation of the AKT/mTOR (mammalian target of rapamycin) pathway in myelinating glial cells is associated with hypermyelination of the brain, but is reportedly insufficient to drive myelination by Schwann cells. We have hypothesized that it requires additional mechanisms downstream of NRG1/ErbB signaling to trigger myelination in the peripheral nervous system. Here, we demonstrate that elevated levels of phosphatidylinositol 3,4,5-trisphosphate (PIP3) have developmental effects on both oligodendrocytes and Schwann cells. By generating conditional mouse mutants, we found that Pten-deficient Schwann cells are enhanced in number and can sort and myelinate axons with calibers well below 1 microm. Unexpectedly, mutant glial cells also spirally enwrap C-fiber axons within Remak bundles and even collagen fibrils, which lack any membrane surface. Importantly, PIP3-dependent hypermyelination of central axons, which is observed when targeting Pten in oligodendrocytes, can also be induced after tamoxifen-mediated Cre recombination in adult mice. We conclude that it requires distinct PIP3 effector mechanisms to trigger axonal wrapping. That myelin synthesis is not restricted to early development but can occur later in life is relevant to developmental disorders and myelin disease.


Subject(s)
Myelin Sheath/physiology , Oligodendroglia/physiology , Phosphatidylinositol Phosphates/metabolism , Schwann Cells/physiology , Aging , Animals , Axons/physiology , Axons/ultrastructure , Brain/physiology , Brain/ultrastructure , Cell Count , Collagen/metabolism , Mice , Mice, Transgenic , Myelin Sheath/ultrastructure , Nerve Fibers, Myelinated/physiology , Nerve Fibers, Myelinated/ultrastructure , Neuroglia/physiology , Neuroglia/ultrastructure , Oligodendroglia/ultrastructure , PTEN Phosphohydrolase/genetics , PTEN Phosphohydrolase/metabolism , Schwann Cells/ultrastructure , Sciatic Nerve/physiology , Sciatic Nerve/ultrastructure
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