Economic Evaluation Approaches in the Field of Disaster Health Management.

BACKGROUND: Economic evaluation approaches are needed to establish useful interventions for saving lives, preventing economic damage, and saving recovery costs at the time of disasters. Thus, the present study is aimed to identify the studies that applied economic evaluation approaches/methods for evaluating the economic costs of disasters. METHODS: A scoping review was conducted to find the eligible studies and perform a comprehensive data analysis. RESULTS: Based on the findings, cost-effectiveness analysis, economic loss assessment, modeling, or mapping, as well as behavioral economic analysis were used as the economic evaluation approaches/methods. CONCLUSIONS: Applying economic evaluation approaches to illustrate the economic costs of disasters is highly recommended. Managing competing priorities and optimizing resources allocations to the most cost-effective interventions can be achieved by cost-effectiveness analysis. The results of economic loss assessment can be used as the basis of disaster preparedness and response planning. Economic modeling can be applied to compare different interventions and anticipate socio-economic effects of disasters. A behavioral economic approach can be effective for decision-making in the field of disaster health management. Further research is needed to identify the advantages and limitations of each economic evaluation method/approach in the field of health in disasters. Such research can preferably be designed as the systematic review and meta-analysis.

[Incapacity to work in prehospital German emergency medical services staff]. / Arbeitsunfähigkeit bei präklinischen Rettungskräften in Deutschland: Ergebnisse der EMS-Health-Studie.

Background: The determination of incapacity to work is a central approach for analyses of absence due to sickness. Nevertheless, no data are yet available for incapacity to work and associated factors in the German prehospital emergency medical services (EMS) staff. Objective: The aim of this analysis was to identify the proportion of EMS staff with at least one incapacity for work (AU) in the previous 12 months and associated factors. Material and methods: This was a nationwide survey study with rescue workers. Factors associated with work disability were identified using multivariable logistic regression, calculating odds ratios (OR) and associated 95% confidence intervals (95% CI). Results: Included in this analysis were 2298 employees of the German emergency medical services (female 42.6%, male 57.2%). Overall, 60.10% of female participants and 58.98% of male participants reported an incapacity for work in the previous 12 months. Incapacity for work was significantly associated with having a high school diploma (high school diploma: OR: 0.51, 95% CI 0.30; 0.88, p = 0.016; reference: secondary school diploma), working in a rural environment (OR: 0.65, 95% CI 0.50; 0.86, p = 0.003) or urban environment (OR: 0.72, 95% CI: 0.53; 0.98, p = 0.037). Furthermore, hours worked per week (OR: 1.01, 95% CI: 1.00; 1.02, p = 0.003) and 5-< 10 years of service (OR: 1.40, 95% CI: 1.04; 1.89, p = 0.025) were associated with higher odds of work disability. Neck and back pain, depression, osteoarthritis, and asthma in the previous 12 months also showed a significant association with work disability in the same time period. Conclusion: This analysis shows that chronic diseases, educational attainment, area of assignment, years of service, and hours worked per week, among others, were associated with incapacity for work in the previous 12 months in German EMS staff.

Working conditions, authorizations, mental health, and job satisfaction of physician assistants in Germany.

Objective: This study explores associations among the overall and facet-specific job satisfaction, work-related factors, responsibilities, and mental health of physician assistants (PAs) in Germany to identify factors that prolong the lifetime and wellbeing of PAs in practice and to counteract the shortage of healthcare staff. Methods: An online survey comprising sociodemographic and work-related items, items from the short questionnaire of general and facet-specific job satisfaction (KAFA), and the Depression, Anxiety, and Stress Scale (DASS-21) were distributed to PAs working in Germany in 2021 (cross-sectional survey design). Descriptive statistics, DASS-21 subscale score analysis, t-test, ANOVA, or Kruskal-Wallis test was used. Results: PAs (n = 169) were working mainly in surgery (23.2%), internal medicine (20.3%), or orthopedics and trauma surgery (17.5%), whereas only a few PAs were working in emergency care, geriatrics, neurology, or oncology. They were responsible for a broad spectrum of medical activities depending on the practice setting. PAs working in emergency care claimed to be the most empowered, followed by PAs in orthopedics and surgery. Almost all PAs carried out documentation, anamnesis, and diagnostic services. Although almost all PAs rated their overall job satisfaction as good, satisfactory, or pleasant (91.6%), single facets of job satisfaction were rated differently. Colleagues and supervisors were assessed very positively, whereas payment and professional activities were rated rather average and development opportunities even worse. PAs working in oncology demonstrated the highest overall job satisfaction, followed by PAs working in geriatrics and emergency care. Overall job satisfaction was significantly negatively associated with depression, anxiety, and stress scores (p ≤ 0.001, p ≤ 0.05, and p ≤ 0.05, respectively). Particularly, female gender, having an urban residence, and PAs working in oncology demonstrated significantly increased anxiety scores. Moreover, depression scores of PAs working in oncology or neurology or with a low net income exceeded critical cutoff values. Conclusion: Interventions aimed at removing the significant negative correlation among job satisfaction, depression, anxiety, and stress scores are needed. To retain PAs in their jobs, salary, autonomy, and development opportunities should be improved and prevention programs for anxiety and depression should be offered. Remarkably, PAs' overall good job satisfaction was mainly determined by good evaluations of supervisors and colleagues.

[Pain, analgesic intake and mental health of German intensive care unit nurses]. / Schmerzen, Schmerzmitteleinnahme und mentale Gesundheit von Intensivpflegenden in Deutschland.

BACKGROUND AND AIM: Since nurses in general are frequently affected by pain and depressive episodes, the aim of this study was to analyze the prevalence of pain, frequency of analgesic intake and the mental health of intensive care nurses. METHODS: This study was a survey study of German intensive care nurses and the questionnaire comprised self-developed items and the short version of the Depression Anxiety Stress Scale (DASS-21). RESULTS: A total of 432 intensive care nurses (82.97% female) were included in the analysis. Recurrent pain was reported by 36.81% (95% confidence interval [CI]: 31.31%; 42.99%) of study participants and chronic pain by 18.52% (95% CI: 14.68%; 23.05%). Body weight (adjusted odds ratio (AOR): 1.02 [95% CI: 1.01; 1.03]; p = 0.006) and sex (male AOR: 0.33 [95% CI: 0.14; 0.78]; p = 0.012) were significantly associated with chronic pain, and sex (male AOR: 0.59 [95% CI: 0.31; 1.00]; p = 0.049) and the presence of sleeping problems (AOR: 2.16 [95% CI: 1.41; 3.31]; p ≤ 0.001) with recurrent pain. Analgesics were used by 52.61% of study participants with chronic/recurrent pain (most frequently used substance: ibuprofen [81.67%]). Study participants with chronic and recurrent pain indicated significantly higher depression, anxiety and stress levels compared to those without pain. CONCLUSION: This study indicates that a large number of participating intensive care nurses are suffering from chronic and recurrent pain. Pain in this population was associated with a variety of factors.

Perceived stress, workload and psychosomatic complaints in inpatient and outpatient care nurses.

Background: Occupational stress, dissatisfaction, higher risk for chronical and psychological disorders impairs the well-being of care nurses staff and maintaining the quality of elderly and disabled care. However, few studies have compared the psychological and physical stress in nurses working in inpatient and outpatient care settings. Aim: The aim of the present study was to compare perceived stress, workload and psychosomatic complaints in nurses working in inpatient and outpatient care settings. Methods: 158 care nurses working in geriatric and disabled care participated in the quantitative cross-sectional survey study. Comparisons of stress, workload and psychosomatic complaints were made between the inpatient and outpatient care group. Results: Nurses working in the outpatient care reported more subjective experience of stress and more workload compared to nurses working in inpatient care. Additionally, nurses working in outpatient care reported more psychosomatic complaints compared to nurses in inpatient care. Conclusions: Our results suggest that inpatient and outpatient nurses experience their nursing activities differently stressful. In future research the differential stress factors need to be explored to provide adequate job training and develop stress prevention programs.

Pain and associated factors in German occupational therapists: a nationwide cross-sectional survey study.

Background: Back pain is a common event in the general German population, but little is known about pain prevalence among occupational therapists (OT). Objective: The aim of this study was to estimate the prevalence of pain and associated factors in German OTs. Methods: We conducted a cross-sectional survey study. The prevalence of acute, chronic, and recurrent pain was calculated, and factors associated with chronic and recurrent pain were identified using multivariate logistic regression analysis. Results: A total of 444 OTs (89.41% female) with a mean age of 37.78 (SD = 11.63) years were included into the final analysis. Prevalence of acute pain was 3.83% (95% confidence interval [95% CI]: 2.25%; 6.06%), of chronic pain 15.54% (95% CI: 12.30%; 19.25%), and of recurrent pain 43.02% (95% CI: 38.36%; 47.77%). The most frequently affected pain site was the lumbar spine. Significantly associated with chronic pain was the level of depression (adjusted odds ratio [AOR]: 1.05 [95% CI 1.00; 1.10]; p ≤ 0.042) of study participants. Recurrent pain was significantly associated with a standing working position, working in geriatrics, stress level, and the level of graduation in multivariate analysis. Conclusion: This study estimated the prevalence of pain and identified factors associated with chronic and recurrent pain in participating OTs. To provide prevention measures and to identify more factors, further studies should be conducted.

[Prevalence of sleep disturbance in intensive care nurses: a post hoc analysis of a cross-sectional study]. / Häufigkeit von Schlafproblemen bei Intensivpflegenden: Eine Post-hoc-Analyse einer Querschnittstudie.

Background: Intensive care nurses have irregular and unusual working hours due to shift work, which can disrupt the natural light-dark rhythm and thus increase the risk for sleep disorders. Aim of the work: The aim of this post hoc analysis was to investigate the prevalence of self-reported sleep problems and associated factors among intensive care nurses working in Germany. Methods: This analysis was a post hoc analysis of a cross-sectional study, which was performed as an online survey. Collected data were sociodemographic, work-related and health-related data. These data were used to calculate the prevalence and respective 95% confidence intervals (95% CI) of sleep problems. Factors associated with sleep problems were identified using the χ2-test, Fisher's exact test, and logistic regression analysis. Results: The link to the online survey was accessed 1163 times and 490 intensive care nurses participated in the survey. A total of 432 intensive care nurses were included in this analysis, of whom 82.87% were women. A total of 57.64% (95% CI: 52.83-62.35%) reported sleep problems. Significantly associated with sleep problems were age (50-59 years odds ratio [OR]: 2.05, 95% CI: 1.00-4.21, p = 0.047 vs. 20-29 years) and living in a family (OR: 0.50, 95% CI: 0.27-0.93, p = 0.029 vs. single/living alone). In addition, depression (OR: 1.09, 95% CI: 1.06-1.12, p ≤ 0.001), anxiety (OR: 1.10, 95% CI: 1.06-1.14, p ≤ 0.001) and stress (OR: 1.09, 95% CI: 1.06-1.12, p ≤ 0.001) levels were significantly associated with sleep problems. Conclusion: Sleep problems were present in one out of every two participating intensive care nurses and in particular mental health was associated with sleep problems.

The prevalence of diseases in German emergency medical services staff: A survey study.

For the general German population, the GEDA study is the main health monitoring study. Since nothing comparable is existing regarding the health of emergency medical services (EMS) staff, the aim of the present study was to estimate the 12-months prevalence of socially relevant diseases and symptoms among German pre-hospital EMS staff. This was a nationwide survey study. For retrieval of information on the health status of participating EMS staff items from the GEDA2014/2015 study were used. Afterwards, 12-months prevalence or proportions and corresponding 95% confidence intervals (95% CI) were calculated. Overall, 2,313 German pre-hospital EMS staff (42.6% female/57.2% male) with a median age of 25.0 (min. 18.0; max. 63.0) years were included into the final analysis. Obesity based on BMI was present in 25.9% (95% CI: 23.5%; 28.4%) of male compared to 15.7% (95% CI: 13.5%; 18.1%) of female study participants. Highest 12-months prevalence in the full study sample were calculated for lower back pain (41.1% [95%: 39.1%; 43.2%]), cervical pain (32.9% [95% CI: 30.9%; 34.8%]), allergies (32.6% [95% CI: 30.7%; 34.6%], depression (13.7% [95% CI: 12.4%; 15.2%]), and hypertension (11.5% [95% CI: 10.3%; 12.9%]). The 12-months prevalence in specific age-/gender-groups were higher for asthma, depression, hypertension, increased blood lipids, and osteoarthritis among study participants compared to the general German population (GEDA study) with the same age and gender (ratio ≥ 1.5). This study indicates that the prevalence of obesity, depression, hypertension, and other disorders is high among study participants and disease prevention measures for pre-hospital EMS staff are needed.

Osteoporotic fractures and subsequent fractures: imminent fracture risk from an analysis of German real-world claims data.

PURPOSE: In osteoporosis, prior fracture is a strong predictor of subsequent fracture. This study aimed to assess the imminent risk of subsequent fracture following an initial fracture in osteoporosis patients in Germany, and to identify clinical and demographic characteristics that are independently associated with subsequent fracture risk. METHODS: In this retrospective, observational cohort study using German real-world claims data, male and female patients aged ≥ 50 years with osteoporosis who experienced an initial ("index") hip/femur, vertebral, forearm/wrist/hand or shoulder/upper arm fracture between 2010 and 2014 were included. The incidence and timing of subsequent fractures during a 1-year follow-up period were analyzed. Independent risk factors for subsequent fracture were identified by multivariate regression analysis. RESULTS: A total of 18,354 patients (mean age: 77 years; standard deviation: 9.8) were included. Of these, 2918 (15.9%) suffered a subsequent fracture during the 1-year follow-up period. The incidence of subsequent fracture was higher following an index vertebral fracture (18.0%) than after an index forearm/wrist/hand fracture (14.1%) or index hip/femur fracture (12.1%). Subsequent 1-year fracture incidence was generally higher in older patients. Index fracture type, age, epilepsy/use of antiepileptics, and heart failure were all independently associated with subsequent fracture risk. CONCLUSION: Osteoporosis patients in Germany are at imminent risk of subsequent fracture during the first year following an initial fracture. They should be targeted for immediate post-fracture treatment to reduce the risk of further fractures, especially in the presence of specific risk factors such as old age or index vertebral fracture.

Prevalence of pain, analgesic self-medication and mental health in German pre-hospital emergency medical service personnel: a nationwide survey pilot-study.

PURPOSE: The aim of this study was to estimate the prevalence of pain, the extent of analgesics intake and the mental health status of German pre-hospital emergency medical service (EMS) personnel. METHODS: We conducted a nationwide online survey, which consisted of sociodemographic and job-related items, questions on pain and analgesics intake and the short-version of the validated Depression-Anxiety-Stress Scale (DASS-21). RESULTS: A total of 774 EMS personnel with a mean age of 33.03 (standard error [SE] 0.37) years were included into the final analysis of which 23.77% were female. Pain was reported by 58.64% (454 of 774) of the study participants with 10.72% (95% confidence interval [CI] 8.54%; 13.29%) suffering from chronic, 1.68% (95% CI 0.89%; 2.87%) from acute and 46.25% (95% CI 41.49%; 51.30%) from recurrent pain, respectively. Most frequent location of pain was lumbar spine. Analgesics were used by 52.76% (239 of 454) of pre-hospital EMS personnel with pain (acute 76.92% / chronic 69.88% / recurrent 47.90%). Moreover, participants with chronic and recurrent pain indicated significantly higher depression (p ≤ 0.001), anxiety (p ≤ 0.001), and stress (p ≤ 0.001) levels compared to those without pain, respectively. CONCLUSION: This study indicates a high prevalence of pain and analgesics usage in participating German pre-hospital EMS personnel and a poorer mental health in those with chronic and recurrent pain. Therefore, disease prevention and health promotion measures are needed to preserve health of pre-hospital EMS personnel.

Characterization of blood donors and non-blood donors in Germany using an online survey.

Objectives of this study were to analyze characteristics influencing blood donation status, to identify anxieties and reasons for (non-)blood donation, and potential channels for future blood donation campaigns. A random population from Germany was interviewed using the online survey tool SoSci Survey. The access link to the questionnaire was distributed via snowball system and the Bavarian Red Cross. Statistical analysis was performed to identify factors influencing blood donation status. A total of 682 participants (27.3% blood donors) with a mean age of 33.4 and a standard deviation (SD) of 12.0 years were included into the analysis. Strongest factor associated with being blood donor was having a blood donor within family and friends (Odds ratio [OR]: 5.05 [95% confidence interval [95% CI]: 2.63; 9.70]; p≤0.001), whereas having anxiety related to blood donation was the strongest factor for being non-blood donor (OR: 0.11 [95% CI: 0.05; 0.21] p≤0.001). Other factors significantly influencing blood donor status were age, health-related quality of life, knowledge on blood donation, being an organ donor and having pre-conditions. Main anxieties avoiding blood donation were fear of physical consequences, and fear of the injection needle. Most frequently mentioned channels which should be used for blood donation campaigns were Instagram and free TV. Involving blood donors into campaigns to recruit new blood donors from their personal environment and to focus campaign content on physical benefits of blood donations might help to recruit new blood donors. In addition, running campaigns stronger on channels such as Instagram might increase their scope.

Risk of falls in patients with low bone mineral density : Analysis of placebo arms from clinical trials.

BACKGROUND: Falls are a major risk factor for osteoporotic fractures. Therefore, the aim of this study was to analyze the risk of falls in patients with low bone mineral density (BMD) and osteoporosis. METHODS: The risk of falls in patients with low BMD and/or osteoporosis was analyzed using data from placebo arms of clinical trials, indexed on clinicaltrials.gov. The risk was estimated using a single arm meta-analysis method and by applying a binary random effects model. In addition, meta-regression analyses were performed to identify associations between risk of falls and age, body mass index (BMI) and BMD. RESULTS: A total of 8762 patients from placebo arms of clinical trials were included into the analysis. Risk of falls was 5.2% (0.052, 95% confidence interval [95% CI] 0.022-0.082; n = 8714; I2 = 97.3%, p ≤ 0.001) in patients with low BMD and/or osteoporosis and 5.9% (0.059, 95% CI 0.036-0.083; n = 7819; I2 = 87.8%, p ≤ 0.001) in patients with osteoporosis. A significant association with risk of falls was identified for age in patients with low BMD and/or osteoporosis. BMD at total hip (TH; coefficient -0.077, 95% CI: -0.113--0.040, p ≤ 0.001; n = 7715) and femoral neck (FN; coefficient -0.044, 95% CI -0.065--0.023, p ≤ 0.001; n = 7662) were significantly associated with risk of falls in patients with osteoporosis. CONCLUSION: This analysis identified the risk of falls in patients with low BMD and osteoporosis and an association of falls with age and BMD. Therefore, patients with osteoporosis need to receive mandatory fall risk mitigation measures, and the BMD at total hip or femoral neck could function as an indicator for the risk of falling.

Estimated epidemiology of osteoporosis diagnoses and osteoporosis-related high fracture risk in Germany: a German claims data analysis.

In 2016, an estimated 143,967 female and 25,315 male patients had a diagnosis of osteoporosis, accounting for 4.44% of the German population. Due to an aging population, an increase in the number of osteoporosis patients and osteoporotic fractures can be expected, posing a substantial burden on healthcare systems. PURPOSE: Osteoporosis is one of the most prevalent diseases in developed countries, mainly affecting older adults. It leads to decreased bone mass, bone microarchitecture deterioration, and increased risk of fracture. This epidemiological study investigated the prevalence and incidence of osteoporosis diagnoses and assessed the number of osteoporosis patients who are at high risk of vertebral/femoral fracture. METHODS: We analyzed German claims data (AOK PLUS) covering 2010-2016. All included patients were diagnosed with osteoporosis (ICD-10 M80.*/M81.*). Vertebral/femoral and other fractures were identified based on respective ICD-10 codes. Patient numbers were extrapolated to the entire German population, based on patient age and gender. RESULTS: In 2016, 169,282 patients (143,967 females and 25,315 males) had prevalent osteoporosis, 25,996 (20,425 females and 5571 males) of which were newly diagnosed that year. Extrapolated prevalence for Germany was 3.61 million patients (4.44% of the German population). Extrapolated incidence was 0.62 million patients. Of patients with prevalent osteoporosis, 13,613 experienced an incident vertebral/femoral fracture in 2016 (German extrapolation: 258,957 patients). Of these, 36.88% received an osteoporosis treatment that year. CONCLUSION: Our study identified a high number of prevalent and incident patients with osteoporosis claims in Germany. The increasing age of the German population will likely lead to a significant increase in the number of patients with osteoporosis over the next decades. Treatment of osteoporosis patients with high fracture risk, especially those with a recent vertebral/femoral fracture, should be of particular focus, as a substantial proportion does not receive a guideline-based treatment.

Risk of falls in postmenopausal women treated with romosozumab: Preliminary indices from a meta-analysis of randomized, controlled trials.

OBJECTIVES: Falls are the well-known risk factor for osteoporotic fractures and some medications can increase the risk of falls. Therefore, the aim of our study is to evaluate the effect of romosozumab on risk of falls in postmenopausal women. METHODS: Studies were searched on PubMed, Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov using the search term "romosozumab." Randomized, clinical trials with romosozumab in postmenopausal women, which met the inclusion criteria and in particular reported on falls in safety or efficacy data, were included into the meta-analysis. Risk ratios (RRs) and corresponding 95% confidence intervals (CIs) were calculated using a binary effects model. RESULTS: A total of four studies with overall 12,128 postmenopausal women with osteoporosis were included into the meta-analysis. Twelve-months treatment with romosozumab reduced the risk of falls nonsignificantly by 16% (RR, 0.84; 95% CI, 0.67-1.04; P = 0.10; n = 11,829). A subgroup analysis with double-blind studies indicated a statistically significant reduction in risk of falls by 20% (RR, 0.80; 95% CI, 0.71-0.92; P ≤ 0.01; n = 11,211). A sequential treatment of romosozumab followed by an antiresorptive medication resulted in a 12% (RR, 0.88; 95% CI, 0.80-0.96; P ≤ 0.01; n = 11,211) reduction of falls in the romosozumab group compared to the control group. CONCLUSIONS: This analysis indicates that romosozumab has a tendency to reduce risk of falls in postmenopausal women with osteoporosis. Nevertheless, our findings are preliminary results with a low significance and to confirm these findings more data and analyses are needed.

Expression and purification of soluble HIV-2 viral protein R (Vpr) using a sandwich-fusion protein strategy.

Viral accessory proteins of the human immunodeficiency virus (HIV), including virus protein R (Vpr), are crucial for the efficient replication of the virus in the host organism. While functional data are available for HIV-1 Vpr, there is a paucity of data describing the function and structure of HIV-2 Vpr. In this report, the construction of a His6-MBP-intein1-Vpr-intein2-Cyt b5-His6 fusion protein is presented. Unlike previous research efforts where only microgram quantities of HIV-1 Vpr could be produced, this construct enabled soluble milligram yields via an Escherichia coli over-expression system. Straightforward protein purification of HIV-2 Vpr was achieved by standard chromatography routines and autocatalytic intein cleavage. Preliminary structural studies by circular dichroism (CD) and NMR spectroscopy revealed that the protein is stable in the presence of micellar concentrations of the detergent DPC and adopts an α-helix secondary structure.

Nanodiscs allow phage display selection for ligands to non-linear epitopes on membrane proteins.

In this work, we exploited a method that uses polytopic membrane proteins as targets for phage display selections. Membrane proteins represent the largest class of drug targets and drug discovery is mostly based on the identification of ligands binding to target molecules. The screening of a phage display library for ligands against membrane proteins is typically hindered by the requirement of these proteins for a membrane environment, which is necessary to retain correct folding and epitope formation. Especially in proteins with multiple transmembrane domains, epitopes often are non-linear and consist of a combination of loops between transmembrane stretches of the proteins. Here, we have used bacteriorhodopsin (bR) as a model of polytopic membrane protein, assembled into nanoscale phospholipid bilayers, so called nanodiscs, to screen a phage display library for potential ligands. Nanodiscs provide a native-like environment to membrane proteins and thus selection of ligands can take place in a near physiological state. Screening a 12-mer phage display peptide library against bR nanodiscs led to the isolation of phage clones binding specifically to bR. We were further able to identify the binding site of selected phage clones proving that the clones bind to extramembranous, non-linear epitopes of bR. Thus, nanodiscs provide a suitable and general tool that allows screening of a phage display library against membrane proteins in a near native environment.

Full-length Vpu and human CD4(372-433) in phospholipid bilayers as seen by magic angle spinning NMR.

HIV-1 Vpu and CD4(372-433), a peptide comprising the transmembrane and cytoplasmic domain of human CD4, were recombinantly expressed in Escherichia coli, uniformly labeled with 13C and 15N isotopes, and separately reconstituted into phospholipid bilayers. Highly resolved dipolar cross-polarization (CP)-based solid-state NMR spectra of the two transmembrane proteins were recorded under magic angle sample spinning. Partial assignment of 13C resonances was achieved. Site-specific assignments were obtained for 13 amino acid residues of CD4(372-433) and two Vpu residues. Additional amino acid type-specific assignments were achieved for 10 amino acid spin systems for both CD4(372-433) and Vpu. Further, structural flexibility was probed with different dipolar recoupling techniques, and the correct insertion of the transmembrane domains into the lipid bilayers was confirmed by proton spin diffusion experiments.

Mapping the interaction between the cytoplasmic domains of HIV-1 viral protein U and human CD4 with NMR spectroscopy.

Viral protein U (VpU) of HIV-1 plays an important role in downregulation of the main HIV-1 receptor CD4 from the surface of infected cells. Physical binding of VpU to newly synthesized CD4 in the endoplasmic reticulum is an early step in a pathway leading to proteasomal degradation of CD4. In this study, regions in the cytoplasmic domain of VpU involved in CD4 binding were identified by NMR spectroscopy. Amino acids in both helices found in the cytoplasmic region of VpU in membrane-mimicking detergent micelles experience chemical shift perturbations upon binding to CD4, whereas amino acids between the two helices and at the C-terminus of VpU show no or only small changes, respectively. The topology of the complex was further studied with paramagnetic relaxation enhancement. Paramagnetic spin labels were attached at three sequence positions of a CD4 peptide comprising the transmembrane and cytosolic domains of the receptor. VpU binds to a membrane-proximal region in the cytoplasmic domain of CD4.