Development of a Definition of Postacute Sequelae of SARS-CoV-2 Infection

Importance

SARS-CoV-2 infection is associated with persistent, relapsing, or new symptoms or other health effects occurring after acute infection, termed postacute sequelae of SARS-CoV-2 infection (PASC), also known as long COVID. Characterizing PASC requires analysis of prospectively and uniformly collected data from diverse uninfected and infected individuals.

Objective

To develop a definition of PASC using self-reported symptoms and describe PASC frequencies across cohorts, vaccination status, and number of infections.

Design, Setting, and Participants

Prospective observational cohort study of adults with and without SARS-CoV-2 infection at 85 enrolling sites (hospitals, health centers, community organizations) located in 33 states plus Washington, DC, and Puerto Rico. Participants who were enrolled in the RECOVER adult cohort before April 10, 2023, completed a symptom survey 6 months or more after acute symptom onset or test date. Selection included population-based, volunteer, and convenience sampling.

Exposure

SARS-CoV-2 infection.

Main Outcomes and Measures

PASC and 44 participant-reported symptoms (with severity thresholds).

Results

A total of 9764 participants (89% SARS-CoV-2 infected; 71% female; 16% Hispanic/Latino; 15% non-Hispanic Black; median age, 47 years [IQR, 35-60]) met selection criteria. Adjusted odds ratios were 1.5 or greater (infected vs uninfected participants) for 37 symptoms. Symptoms contributing to PASC score included postexertional malaise, fatigue, brain fog, dizziness, gastrointestinal symptoms, palpitations, changes in sexual desire or capacity, loss of or change in smell or taste, thirst, chronic cough, chest pain, and abnormal movements. Among 2231 participants first infected on or after December 1, 2021, and enrolled within 30 days of infection, 224 (10% [95% CI, 8.8%-11%]) were PASC positive at 6 months.

Conclusions and Relevance

A definition of PASC was developed based on symptoms in a prospective cohort study. As a first step to providing a framework for other investigations, iterative refinement that further incorporates other clinical features is needed to support actionable definitions of PASC.

Severe Vitamin K-dependent Coagulopathy from Rodenticide-contaminated Synthetic Cannabinoids: Emergency Department Presentations

Introduction

Synthetic cannabinoids are a rapidly expanding subset of designer drugs widely available in the United States since 2008. In Illinois during the spring of 2018, over 160 documented cases of bleeding and prolonged coagulopathy occurred secondary to contaminated synthetic cannabinoids.

Methods

We conducted a retrospective cohort study consisting of 38 patients to describe the initial emergency department (ED) presentation, diagnosis, and treatment.

Results

Through serum testing we found that three long-acting anticoagulant rodenticides (LAAR) were detected in patients who had inhaled these tainted products: brodifacoum, difenacoum, and bromodialone.

Discussion

This study encompasses the largest ED presentation of LAAR poisoning via the inhalational route known to date.

Conclusion

The emergency physician should be aware of the potential for tainted coingestants as the cause of undifferentiated coagulopathy.

Identical and Nonidentical Twins: Risk and Factors Involved in Development of Islet Autoimmunity and Type 1 Diabetes

OBJECTIVE

There are variable reports of risk of concordance for progression to islet autoantibodies and type 1 diabetes in identical twins after one twin is diagnosed. We examined development of positive autoantibodies and type 1 diabetes and the effects of genetic factors and common environment on autoantibody positivity in identical twins, nonidentical twins, and full siblings.

RESEARCH DESIGN AND METHODS

Subjects from the TrialNet Pathway to Prevention Study (N = 48,026) were screened from 2004 to 2015 for islet autoantibodies (GAD antibody [GADA], insulinoma-associated antigen 2 [IA-2A], and autoantibodies against insulin [IAA]). Of these subjects, 17,226 (157 identical twins, 283 nonidentical twins, and 16,786 full siblings) were followed for autoantibody positivity or type 1 diabetes for a median of 2.1 years.

RESULTS

At screening, identical twins were more likely to have positive GADA, IA-2A, and IAA than nonidentical twins or full siblings (all P < 0.0001). Younger age, male sex, and genetic factors were significant factors for expression of IA-2A, IAA, one or more positive autoantibodies, and two or more positive autoantibodies (all P ≤ 0.03). Initially autoantibody-positive identical twins had a 69% risk of diabetes by 3 years compared with 1.5% for initially autoantibody-negative identical twins. In nonidentical twins, type 1 diabetes risk by 3 years was 72% for initially multiple autoantibody-positive, 13% for single autoantibody-positive, and 0% for initially autoantibody-negative nonidentical twins. Full siblings had a 3-year type 1 diabetes risk of 47% for multiple autoantibody-positive, 12% for single autoantibody-positive, and 0.5% for initially autoantibody-negative subjects.

CONCLUSIONS

Risk of type 1 diabetes at 3 years is high for initially multiple and single autoantibody-positive identical twins and multiple autoantibody-positive nonidentical twins. Genetic predisposition, age, and male sex are significant risk factors for development of positive autoantibodies in twins.

A Compression Kit of a Stocking and Three Superimposed Leggings Is Easy to Don and Dose Adjustable

BACKGROUND

Forty percent of patients with chronic venous insufficiency (CVI) do not wear their indicated and prescribed compression stockings. Difficulties in donning and a feeling of constraint are the most common reasons for non-adherence.

OBJECTIVE

The aim was to develop a compression stocking system that is easy to don and dose adjustable.

METHODS

A modular compression stocking kit composed of an understocking and three superimposable leggings (SLLLs) was developed. Substocking pressures (P) at the thinnest part above the ankle (cB level) were 17 mm (understocking) + 15 + 10 + 10 mmHg (3 superimposed leggings; Hatra method). Twenty healthy subjects and 20 patients over 65 years with CVI donned the SLLL compression kit. P was measured in vivo (Picopress method) at the transition of the Achilles tendon to the calf muscle (level cB1) during rest and ankle movements (DSI; dynamic stiffness index) and compared with a strong compression stocking of 40 mmHg (S40).

RESULTS

Twenty (20/20) patients aged over 65 with CVI (C4-6) successfully donned the SLLL compression kit without aid, compared with 12 (12/20) who were able to don the S40 without aid (p = .02). In vivo resting P at level cB1 was 34.3 mmHg (SLLL) compared with 37.3 mmHg (S40) (p = .1). The DSI was 16.1 (SLLL) compared with 17.9 (p = .79; S40; CVI group).

CONCLUSION

The physical properties of the SLLL compression stocking kit correspond to the characteristics of a strong stocking at rest and exercise (DSI). The donning success rate is excellent (100%). A further potential advantage is that the SLLL leg compression kit is dose adjustable, according to indication or patient tolerance. Wearing comfort over periods of several days and clinical effectiveness need to be investigated in future trials.

A prospective clinical trial to assess lapatinib effects on cutaneous squamous cell carcinoma and actinic keratosis

BACKGROUND

Antiepidermal growth factor receptor (EGFR)-targeted therapy is widely used in many epithelial cancer types. We investigated lapatinib effects on cutaneous squamous cell carcinoma (cSCC) scheduled for resection and in coexisting precursor lesions (actinic keratosis (AK) and Bowen's disease (BD)) in a phase 2 mode of action clinical trial including a histological workup of the cSCC.

PATIENTS AND METHODS

We initiated a prospective single-centre, open-label, non-controlled clinical study with translational intentions to investigate changes in size and histopathological features in cSCC after a 14-day period of neoadjuvant lapatinib therapy at a dose of 1500 mg/day prior to surgery, to quantify the impact on AK and BD in the same patient after 56 days and to evaluate the tolerability in patients with cSCC and precursor lesions.

RESULTS

10 immunocompetent male patients were included with a mean age of 73 years (range 59-87). 8 patients were treated with the study medication lapatinib 1500 mg/day for a total duration of 56 days according to the protocol and were available for full analysis, whereas 2 patients had to discontinue treatment during the first 2 weeks because of adverse events (diarrhoea, pancreatitis). Tolerability was acceptable with only 1 related grade III adverse event. A reduction in tumour size of cSCC was documented in 2 of 8 evaluable patients after 14 days of treatment. The mean regression of captured precursor lesions was 30% after 56 days of treatment and 36% 28 days after therapy cessation.

CONCLUSIONS

Short-term lapatinib resulted in a cSCC tumour reduction in 2 of 8 patients. In addition, there was a clinically documented reduction of AK in 7 of 8 patients encouraging larger clinical trials, especially in high-risk patients with cSCC such as organ transplant recipients.

TRIAL REGISTRATION NUMBER

NCT0166431.

Donning devices (foot slips and frames) enable elderly people with severe chronic venous insufficiency to put on compression stockings

OBJECTIVE/BACKGROUND

Compression therapy is highly effective in the treatment of post-thrombotic syndrome and venous leg ulcer. On average, 50-60% of the patients cooperate with compression therapy. Therefore, it is necessary to improve the user-friendliness. This prospective study investigated whether the use of donning devices can contribute to improving user-friendliness.

METHODS

Forty patients aged >65 years with severe chronic venous insufficiency (CVI; C4-C6) successively donned compression stockings in a randomized order: one 40 mmHg (CS40) or two superimposed 20 mmHg (CS20+20), each with open toe (CS-o-t) and closed toe (CS-c-t), using donning devices (three foot slips for CS-o-t; two foot slips and three frames for CS-c-t). The study endpoint was that the stocking was completely donned and correctly positioned on the patient's leg. The success rate and its association with age, sex, first time versus second time user, body mass index, abdominal circumference, ability to reach the forefoot with the hand, and hand grip strength were analyzed. Additionally, subjective evaluation by the patients was performed.

RESULTS

Without donning devices, success with CS40-c-t was 60% (24/40 patients) and with CS20+20-c-t 70% (28/40 patients) (p = .220). Using donning devices increased success rates significantly. With CS40-o-t the success rate was 88% (35/40 patients; p = .001) and with CS40-c-t it was 90% (36/40 patients; p = .002). With CS20+20-o-t and CS20+20-c-t, the success rate was 88% (35/40 patients; p = .016). The proportion of patients who successfully used either CS40 or CS20+20 increased from 73% to 93%. Relevant for the patients' success was the ability to reach the forefoot with the hand, and hand grip strength. Subjectively, donning with a device was rated significantly better than without.

CONCLUSION

Donning devices significantly improve the ability of elderly patients with CVI to don compression stockings successfully. However, there are differences in user-friendliness among the devices..

[Martorell Hypertensive Ischaemic Leg Ulcer]

Martorell hypertensive ischaemic leg ulcer (HYTILU) represents an important differential diagnosis of painful leg ulcerations. Stenotic subcutaneous arteriolosclerosis in patients with long-standing arterial hypertension finally leads to skin infarction. The typical histological changes are very similar in Martorell HYTILU and calciphylaxis. This raises the hypothesis that the two entities may have a common pathogenesis. Martorell HYTILU presents as an extremely painful ulcer that is regularly located at the laterodorsal lower leg or at the Achilles tendon. Because of its inflammatory and violaceous wound edges and its tendency to progression, clinicians unaware of the diagnosis Martorell HYTILU might misdiagnose pyoderma gangrenosum or necrotising cutaneous vasculitis start an immunosuppressive treatment and avoid surgical diagnostic and therapeutic procedures. Instead, necrosectomy and split skin grafting are the treatment of choice for Martorell HYTILU.

Cu(1 1 1) supported graphene as a substrate for magnetic dimers with a large magnetic anisotropy: relativistic density-functional calculations

We report on our relativistic density-functional investigations of the properties of transition-metal dimers adsorbed on a graphene monolayer supported by a Cu(1 1 1) substrate, which extends our studies of dimers in the gas-phase and adsorbed on a freestanding graphene layer (Błoński and Hafner 2014 J. Phys.: Condens. Matter 26 146002). The presence of the Cu(1 1 1) substrate enhances the interaction between the dimer and the support. For homoatomic dimers such as Ir2 and Pt2 a flat adsorption geometry is now preferred over an upright geometry, which is stable on a graphene monolayer. The magnetic moment of the dimer is strongly reduced, the magnetic anisotropy is very low-in contrast to the strong anisotropy of free and graphene-supported Ir2 and Pt2 dimers. For heteroatomic IrCo and PtCo dimers the upright geometry with the Co atom located in a sixfold hollow of the graphene layer is preserved, but the stronger interaction with the support leads to a further enhancement of the large magnetic anisotropy energy of IrCo to 0.2 eV/dimer, while that of PtCo is reduced. The mechanism determining the magnetic anisotropy is discussed in relation to the electronic structure of the dimers.

Multifocal central nervous system demyelination and Lhermitte's phenomenon secondary to combination chemotherapy for chronic lymphocytic leukaemia

The CRF regime (cyclophosphamide, rituximab and fludarabine) is used for the treatment of chronic lymphocytic leukaemia. We report a case of diffuse CNS demyelination following treatment with CRF, presenting with Lhermitte's phenomenon, and imaging and neurophysiological evidence of demyelination. Fludarabine is the most likely causative agent, although CNS demyelination has not been previously described in low dose therapy.

Non-invasive pressure measurement of the great saphenous vein in healthy controls and patients with venous insufficiency

OBJECTIVES

Venous pressure measurement using an intravenous catheter is the sole method for the diagnosis of venous hypertension in patients with chronic venous insufficiency. A noninvasive tool to quantify increased venous pressure is essential for studying venous pathophysiology. Aim of the study was to investigate the value of controlled compression ultrasound (CCU) for noninvasive assessment of venous pressure (VP) of the great saphenous vein (GSV) in healthy persons and patients with venous insufficiency to quantify venous hypertension.

METHODS

An optimal visible part of the GSV directly above the ankle was marked on the skin and compressed under ultrasound control and pressure needed for complete compression of the vein was recorded using a pressure manometer with a translucent silicone membrane. Complete insufficiency of the GSV (Hach IV) was documented by duplex ultrasound by an independent investigator before start of the study. VP measurement was performed while normal breathing, deep inspiration and expiration and during a standardized Valsalva maneuver.

RESULTS

Twenty controls and 19 patients with complete insufficiency of the GSV were included. Valsalva maneuver induced a slight increase in VP in controls (20.1 ± 4.5 vs 25.1 ± 6.6 mbar) but a significant higher increase in patients from 26 to 37 mbar (IQR 18.5-28.0 vs 31.5-43.0; p < 0.001).

CONCLUSION

Noninvasive venous pressure measurement of the great saphenous vein using CCU is feasible and documents an increased pressure during Valsalva maneuver in Hach IV patients compared to healthy controls.

Promoting use of booster seats in rural areas through community sports programs

BACKGROUND

Booster seats reduce mortality and morbidity for young children in car crashes, but use is low, particularly in rural areas. This study targeted rural communities in 4 states using a community sports-based approach.

OBJECTIVE

The Strike Out Child Passenger Injury (Strike Out) intervention incorporated education about booster seat use in children ages 4-7 years within instructional baseball programs. We tested the effectiveness of Strike Out in increasing correct restraint use among participating children.

METHODS

Twenty communities with similar demographics from 4 states participated in a nonrandomized, controlled trial. Surveys of restraint use were conducted before and after baseball season. Intervention communities received tailored education and parents had direct consultation on booster seat use. Control communities received only brochures.

RESULTS

One thousand fourteen preintervention observation surveys for children ages 4-7 years (Intervention Group [I]: N = 511, Control [C]: N = 503) and 761 postintervention surveys (I: N = 409, C: N = 352) were obtained. For 3 of 4 states, the intervention resulted in increases in recommended child restraint use (Alabama +15.5%, Arkansas +16.1%, Illinois +11.0%). Communities in 1 state (Indiana) did not have a positive response (-9.2%). Overall, unadjusted restraint use increased 10.2% in intervention and 1.7% in control communities (P = .02). After adjustment for each state in the study, booster seat use was increased in intervention communities (Cochran-Mantel-Haenszel odds ratio 1.56, 95% confidence interval [1.16-2.10]).

CONCLUSIONS

A tailored intervention using baseball programs increased appropriate restraint use among targeted rural children overall and in 3 of 4 states studied. Such interventions hold promise for expansion into other sports and populations.

Sickle cell disease patients' perceptions of emergency department pain management

Patients with sickle cell disease (SCD) experience painful crises that often require admission to the emergency department (ED) for pain management. Factors such as ED overcrowding and negative perception and stigmatization of SCD may impact patients' perceptions of the quality of pain management in the ED. Data from a multisite prospective cohort study was assessed to determine whether demographic (age and sex), clinical (time to administration of initial analgesia, number of analgesic doses, discharge disposition, and clinical site), or interpersonal factors (separately measured perceptions of being treated with trust and respect by ED triage nurses, nurses, and physicians) were associated with patient ratings of their pain management in the ED. Patients were adults with SCD seen at 3 EDs (2 urban and 1 rural). Demographic and clinical information was derived from medical record review; interpersonal and ED pain management ratings were derived from interviews conducted 1 week post ED visit. A total of 209 interviews by 98 patients were analyzed. Results indicated significant differences among the ED sites on the demographic, clinical, and interpersonal factors. Overall, patients reported being treated with trust and respect by ED clinicians. Adjusted logistic regression analyses indicated that ED clinical site 1 (odds ratio [OR], 10.42; 95% confidence interval [Cl], 1.44-7.36) and being treated with trust and respect by the ED physician (OR, 25.53; 95% CI, 2.07-314.96) predicted good ED pain management ratings. Interpersonal health care experiences may be an important indicator of patient satisfaction and quality of care received by patients with SCD in the ED.

Post-surgical scalp wounds with exposed bone treated with a plant-derived wound therapeutic

OBJECTIVE

To evaluate the efficacy of a plant-derived wound dressing, a mixture of hypericum oil (Hypericum perforatum) and neem oil (Azadirachta indica), in scalp wounds with exposed bone.

METHOD

A retrospective review was conducted of all patients presenting with scalp wounds with exposed bone following the excision of skin tumours and treated with a plant-derived wound dressings (1 Primary Wound Dressing; Phytoceuticals AG), from January to July 2011. Time to healing, wound size, area of exposed bone, ease of handling, pain and complications were evaluated.

RESULTS

Nine consecutive patients were analysed retrospectively. The patients' mean age was 81.2 ± 8.5 years (63-90 years), with a mean wound size of 13.2 ± 6.8cm(2) (0.4-22.6cm(2)) and 6.8 ± 6.5cm(2) (0.3-20.7cm(2)) of exposed bone. The time to complete healing by secondary intention was 4-20 weeks. A rapid induction of granulation tissue was observed, which covered the entire exposed bone surface in six out of nine cases (67%) after 4 weeks, and showed a reduction in the mean area of exposed bone of 95%. Dressing change was easy and without pain and there were no complications.

CONCLUSION

This retrospective, non-controlled analysis suggests that ONE is a very simple to use, safe and potentially effective therapy for the treatment of scalp wounds with exposed bone.

DECLARATION OF INTEREST

There were no external sources of funding for this study. The authors have no conflict of interest to declare.

Mammalian target of rapamycin (mTOR) inhibitors slow skin carcinogenesis, but impair wound healing

BACKGROUND

Recent studies suggest that patients on mammalian target of rapamycin (mTOR) inhibitors experience a reduction in cutaneous carcinogenesis by an estimated 50% or more compared with calcineurin inhibitors. While randomized trials are running, organ transplant recipients are frequently switched from calcineurin inhibitors to mTOR inhibitors when cutaneous carcinogenesis increases.

OBJECTIVES

To slow carcinogenesis in our patient, a heart transplant recipient with a neuropathic diabetic foot syndrome who had developed cutaneous carcinogenesis at a rate of more than 20 squamous cell carcinomas (SCC) annually.

METHODS

The patient's immunosuppression was switched from the calcineurin inhibitor ciclosporin to the mTOR inhibitor everolimus.

RESULTS

Carcinogenesis slowed to six SCC annually; however, he developed recalcitrant diabetic foot ulcers which were purely neuropathic and nonangiopathic, and a limb-threatening fistulating necrotic erysipelas of the right leg. Both sites responded poorly to antibiotic therapy, offloading and debridement. This skin fistula became chronic and some toes were at risk for minor amputation. In view of the propensity for mTOR inhibitors to impair would healing, immunosuppression was switched back to ciclosporin. All wounds healed rapidly, but skin carcinogenesis rose to former levels.

CONCLUSIONS

This case impressively illustrates the clinical dilemma for mTOR inhibitor use where benefit in carcinogenesis is counterbalanced by impairment in wound healing. Changes in immunosuppressive regimens should thus be made on an individual basis with careful consideration of the relative risks.

Evidence that venous hypertension causes stasis dermatitis

A clinical model to examine the hypothesis that venous hypertension of the lower leg per se can cause lower leg stasis dermatitis is described. To prove this concept, we retrospectively studied a consecutive series of 38 patients with lower leg dermatitis who underwent phlebological examination at our consultation over a period of four years. Among those patients who had an insufficiency of the superficial veins only, without insufficiency of the deep veins, 22 had undergone patch testing to common allergens in phlebology. We found 10 patients with a stasis dermatitis of the lower leg and an incompetent great saphenous vein, six of whom had no detectable contact sensitization at all and another four exclusively to phlebologically irrelevant substances, e.g. nickel, cobalt, chromate or epoxid resin. All these 10 patients showed long saphenous vein incompetence from the groin to the medial aspect of the leg. All were operated by classical flush ligation and saphenectomy. Lower leg dermatitis healed in all 10 patients within 8–12 weeks and no recurrence was observed (1 year follow-up). These results support clinical experience that venous hypertension alone indeed can cause lower leg dermatitis.

ADAM metallopeptidase domain 17 (ADAM17) is naturally processed through major histocompatibility complex (MHC) class I molecules and is a potential immunotherapeutic target in breast, ovarian and prostate cancers

Selection of suitable antigens is critical for the development of cancer vaccines. Most desirable are over-expressed cell surface proteins that may serve as targets for both antibodies and T cells, thus maximizing a concerted immune response. Towards this goal, we characterized the relevance of tumour necrosis factor-α-converting enzyme (ADAM17) for such targeted therapeutics. ADAM17 is one of the several metalloproteinases that play a key role in epidermal growth factor receptor (EGFR) signalling and has recently emerged as a new therapeutic target in several tumour types. In the present study, we analysed the expression profile of ADAM17 in a variety of normal and cancer cells of human origin and found that this protein is over-expressed on the surface of several types of cancer cells compared to the normal counterparts. Furthermore, we analysed the presentation of a human leucocyte antigen (HLA)-A2-restricted epitope from ADAM17 protein to specific T cells established from normal donors as well as ovarian cancer patients. Our analysis revealed that the HLA-A2-restricted epitope is processed efficiently and presented by various cancer cells and not by normal cells. Tumour-specific T cell activation results in the secretion of both interferon-γ and granzyme B that can be blocked by HLA-A2 specific antibodies. Collectively, our data present evidence that ADAM17 can be a potential target antigen to devise novel immunotherapeutic strategies against ovarian, breast and prostate cancer.

Entropy effects in hydrocarbon conversion reactions: free-energy integrations and transition-path sampling

The standard approach to ab initio simulations of activated chemical processes is based on the harmonic-oscillator/rigid-rotor approximation to transition state theory. However, there is increasing evidence that these approximations fail for reactions involving loosely bound reactant and/or transitions states where entropy makes a significant contribution to the free-energy reaction barrier. Examples are provided by the conversion (proton exchange, dehydrogenation, monomolecular cracking) of short alkanes over acidic zeolites. For proton exchange and monomolecular cracking the reaction path may be described reasonably well by simple vectorial reaction coordinates and the free energy of activation may be derived by free-energy integration schemes such as the Blue-Moon ensemble technique in combination with constrained ab initio molecular dynamics simulations. For alkane dehydrogenation, however, several reaction scenarios are in competition and techniques such as transition-path sampling must be used to determine the dominant reaction mechanism. In our paper we describe the fundamental aspects of these techniques and discuss their application to compute free-energy barriers for proton exchange between isobutane and acidic chabazite and for monomolecular cracking of propane. Dehydrogenation of propane has been studied using transition-path sampling. In this case the static approach based on harmonic transition state theory not only fails in producing accurate reaction barriers but even leads to incorrect predictions of reaction intermediates and products.

Verbesserung der Kompressionstherapie im retromalleolären Raum durch Pelotten

Der retromalleoläre Raum ist von der chronischen venösen Insuffizienz oft besonders stark betroffen. Aufgrund seiner konkaven Form wird er von der Kompressionstherapie weitgehend ausgespart. Die vorliegende Arbeit hat zum Ziel, den Andruck von Kompressionsverbänden im retromalleolären Raum mit und ohne Pelotte zu untersuchen. ,Methode: Bei zehn gesunden Probanden wurde am rechten Unterschenkel ein Kompressionsverband mit 40 mmHg Ruheandruck angelegt. Zur Messung des Andrucks wurde der Oxford-Pressure-Monitor MK II verwendet. Der Ruheandruck wurde an zwei Messpunkten, nämlich medial und lateral supramalleolär, kontrolliert. Gleichzeitig wurde der Ruhedruck medial und lateral retromalleolär mit und ohne Schaumgummipelotte gemessen. Ergebnisse: Ohne Pelotte wurden retromalleolär medial bzw. lateral Druckwerte von 7 ± 1 bzw. 10 ± 4 mmHg, mit Pelotte solche von 55 ± 9 bzw. 68 ± 20 mmHg gemessen (p = 0,0002; p = 0,00001). Schlussfolgerung: Der retromalleoläre Raum wird von der Kompressionstherapie weitgehend ausgespart. Erst durch die Auspolsterung mit Pelotten entsteht ein effektiver Andruck. Die Verwendung von Pelotten kann sowohl präventiv als auch therapeutisch zur Behandlung der chronischen venösen Insuffizienz im retromalleolären Raum eingesetzt werden.

Periodic DFT calculations of the stability of Al/Si substitutions and extraframework Zn2+ cations in mordenite and reaction pathway for the dissociation of H2 and CH4

The local stability of Al atoms replacing Si in the zeolite framework is compared for all inequivalent tetrahedral (T) sites in mordenite. For Al/Si substitutions in two T sites the stable location of the compensating extraframework Zn(2+) cation forming a Lewis acid site is determined. In the most stable Zn-MOR structures Zn(2+) is located in a small ring (5MR, 6MR) containing two Al/Si substitutions. In less stable structures the Al atoms are placed at larger distances from each other and Zn(2+) interacts with only one Al site. The simulated adsorption of H(2) and CH(4) shows that adsorption strength decreases with increasing stability of the Zn(2+) Lewis site. A higher adsorption strength is observed for Zn(2+) deposited in the 5MR than for the 6MR. The reactivity of a series of stable Zn(2+) Lewis sites is tested via the dissociative adsorption of H(2) and CH(4). The heterolytic dissociation of the adsorbed molecule on the extraframework Zn(2+) cation produces a proton and an anion. The anion binds to Zn(2+) and proton goes to the zeolite framework, restoring a Brønsted acid site. Because bonding of the anion to Zn(2+) is almost energetically equivalent for Zn(2+) in any of the extraframework positions the dissociation is governed by stabilizing bonding of the proton to the framework. Those structures which can exothermically accommodate the proton represent reaction pathways. Due to the repulsion between the proton and Zn(2+) the most favorable proton-accepting O sites are not those of the ring where Zn(2+) is deposited, but O sites close to the ring. Large differences are observed for neighboring positions in a- and b-directions and those oriented along the c-vector. Finally, among the stable Zn(2+) Lewis sites not all represent reaction pathways for dehydrogenation. For all of them the dissociation of H(2) is an exothermic process. In structures exhibiting the highest reactivity the Al/Si substitutions are placed at a large distance and the Zn(2+) cation interacts with O-atoms next to Al in the T4 site of the 5MR. This Lewis site is strong enough to break the C-H bond in the CH(4) molecule.

Carbocation Branching Observed in a Simulation

We have observed the branching rearrangement of a straight-chain secondary carbocation (C9H19+) in an ab initio molecular dynamics (AIMD) reverse-annealing (rising-temperature) simulation. The mechanism observed is one involving closed (protonated-cyclopropane) structures, previously observed in traditional geometry optimization calculations. However, the simulations give us a better understanding of the dynamics involved, leading to two advances: a simpler description of carbenium ion structures in general and the discovery of important entropy effects.

Short-Range Order in Liquid Aluminum Chloride: Ab Initio Molecular Dynamics Simulations and Quantum-Chemical Calculations

We use ab initio molecular dynamics simulations based on density-functional theory and quantum-chemistry calculations on molecular clusters to examine the structure of liquid AlCl3. In the past, conflicting descriptions of the short-range-order in molten AlCl3, based on either edge-sharing dimers or corner-sharing oligomers, have been proposed. This liquid also poses a simulation challenge, due to the possibility of ring-like trimers which can be metastable on the order of >10 ps. Simulations which begin with monomers, either random or ordered, appear to be able to produce proper ratios of ring-trimer to dimer-plus-tail molecular structures without the need to achieve long-time scale chemical equilibrium. Single-molecule calculations lend further support to the conclusion that the liquid is composed largely of edge-sharing dimers.

Ab initio based tight-binding molecular dynamics simulation of the sticking and scattering of O2∕Pt(111)

The sticking and scattering of O(2)Pt(111) has been studied by tight-binding molecular dynamics simulations based on an ab initio potential energy surface. We focus, in particular, on the sticking probability as a function of the angle of incidence and the energy and angular distributions in scattering. Our simulations provide an explanation for the seemingly paradox experimental findings that adsorption experiments suggest that the O(2)Pt(111) interaction potential should be strongly corrugated while scattering experiments indicate a rather small corrugation. The potential energy surface is indeed strongly corrugated which leads to a pronounced dependence of the sticking probability on the angle of incidence. The scattered O(2) molecules, however, experience a rather flat surface due to the fact that they are predominantly scattered at the repulsive tail of the potential.

[The role of surgery in the treatment of acne scars]

Severe acne lead to inesthetic scars on the face of young adults. A new classification based on the morphology of acne scars allows to establish the more appropriate therapeutic strategy. The surgical technics are: punch-excision, punch-elevation, subcission, dermal graft or adipose tissue autotransplantation. Skin resurfacing by dermabrasion, CO2 or Erbium/YAG laser or laser remodeling could be performed as a complement of the surgery. By associating these treatments acne scars are greatly improved.

Thrombophilie bei Patienten mit venösen Ulzera

Hintergrund: Bei Patienten mit venösen Ulzera liegt die Prävalenz der Faktor-V-Leiden-Mutation bei 23 bis 26%. Wir untersuchten die wichtigsten Thrombophilie-assoziierten Gerinnungsparameter bei Patienten mit venösem Ulkus mit oder ohne postthrombotischem Syndrom. Patienten, Methodik: Fall-Kontroll-Studie mit 73 konsekutiven Patienten mit venösen Ulzera und 45 Kontrollpersonen. Anamnese und duplexsonographische bzw. phlebographische Abklärung. Folgende Gerinnungsparameter wurden bestimmt: Antithrombin III, Protein C und Protein S, Faktor-V-Leiden-Mutation, Prothrombinmutation (G20210A), Lupus Antikoagulans, Antikardiolipin-Antikörper, Homocysteinkonzentration und die Mutation (C677T) der Methylentetrahydrofolat-Reduktase (MTHFR). Ergebnisse: 42 Patienten hatten ein postthrombotisches Syndrom: 52% hatten mindestens einen Thrombophilie-assoziierten Gerinnungsbefund (p = 0,001), 33% eine Zweier-Kombination (p = 0,001) und zusätzlich in 14% eine Dreier-Kombination (p = 0,0002). Die Faktor-V-Leiden-Mutation fand sich in 38% (p = 0,0001). 31 Patienten hatten eine primäre venöse Insuffizienz (kein postthrombotisches Syndrom): 39% hatten mindestens einen Thrombophilie-assoziierten Gerinnungsparameter (p = 0,14), 3% eine Zweier-Kombination (p = 1,0) und 0% eine Dreier-Kombination. Die Faktor-V-Leiden-Mutation fand sich in 16% (p = 0,11). Schlussfolgerung: Patienten mit postthrombotischen venösen Ulzera haben stark gehäuft (52%) Thrombophilie-assoziierte Gerinnungsbefunde. In 47% liegen Kombinationen der „klassischen“ Thrombophilie-Parameter vor. Routinemäßige Abklärungen des Thrombophiliestatus bei venösen Ulzera sind mangels Konsequenzen und wegen der hohen Kosten jedoch nicht angezeigt.

A Density Functional Theory Study of Molecular and Dissociative Adsorption of H2 on Active Sites in Mordenite

Adsorption and chemisorption of H2 in mordenite is studied using ab initio density functional theory (DFT) calculations. The geometries of the adsorption complex, the adsorption energies, stretching frequencies, and the capacity to dissociate the adsorbed molecule are compared for different active sites. The active centers include a Brønsted acid site, a three-coordinated surface Al site, and Lewis sites formed by extraframework cations: Na+, Cu+, Ag+, Zn2+, Cu2+, Ga3+, and Al3+. Adsorption properties of cations are compared for a location of the cation in the five-membered ring. This location differs from the location in the six-membered ring observed for hydrated cations. The five-membered ring, however, represents a stable location of the bare cation. In this position any cation exhibits higher reactivity compared with the location in the six-membered ring and is well accessible by molecules adsorbed in the main channel of the zeolite. Calculated adsorption energies range from 4 to 87 kJ/mol, depending on electronegativity and ionic radius of the cation and the stability of the cation-zeolite complex. The largest adsorption energy is observed for Cu+ and the lowest for Al3+ integrated into the interstitial site of the zeolite framework. A linear dependence is observed between the stretching frequency and the bond length of the adsorbed H2 molecule. The capacity of the metal-exchanged zeolite to dissociate the H2 molecule does not correlate with the adsorption energy. Dissociation is not possible on single Cu+ cation. The best performance is observed for the Ga3+, Zn2+, and Al3+ extraframework cations, in good agreement with experimental data.

Ab initio density-functional study of the bridging addition of acrylonitrile on the Si(100) surface

Acrylonitrile may react with the Si(100) surface in a number of ways. Fifteen different configurations have been identified. This study which complements an earlier study devoted to cycloadditions and bonds involving a single atom deals essentially with configurations involving cumulative double bonds. Factors affecting the relative stability of various mesomeric forms are shown to be the proximity to tetrahedral geometry and the compatibility of the dipole form with buckled structures. Tripods are shown to be a way to accommodate a priori unfavorable structures.

Theoretical Investigation of CO Interaction with Copper Sites in Zeolites: Periodic DFT and Hybrid Quantum Mechanical/Interatomic Potential Function Study

Periodic DFT and combined quantum mechanics/interatomic potential function (QM-pot) models were used to describe the interaction of CO with the Cu+ sites in FER. The CO stretching frequencies were calculated using omega(CO)(CCSD(T))/r(CO)(DFT) scaling method relating frequencies determined using a high-level quantum-chemical (coupled clusters) method for simple model carbonyls to CO bond lengths calculated using periodic DFT and QM-pot methods for the Cu+-zeolite system. Both periodic DFT and QM-pot models together with omega(CO)/r(CO) scaling describe the CO stretching dynamics with the "near spectroscopic accuracy", giving nu(CO) = 2156 cm(-1) in excellent agreement with experimental data. Calculations for various Cu+ sites in FER show that both types of Cu+ sites in FER (channel-wall sites and intersection sites) have the same CO stretching frequencies. Thus, the CO stretching frequencies are not site-specific in the CO/Cu+/FER system. The convergence of the results with respect to the model size was analyzed. When the same exchange-correlation functional is used the adsorption energies from periodic DFT and QM-pot are in good agreement (about 2 kcal/mol difference) but substantially larger than those of the experiment. The adsorption energy calculated with the B3LYP functional agrees with available experimental data. The overestimation of the adsorption energy in DFT calculations (periodic or QM-pot) is related to a red-shift of the CO stretching mode, both result from an underestimation of the HOMO(5sigma)-LUMO(2pi) gap of CO and the consequent overestimation of the Cu(+)(d)-CO(2pi*) back-donation. For the adsorption energy, this can be overcome by the use of hybrid B3LYP exchange-correlation functional. For the frequency calculations, the DFT problem can be overcome by the use of the omega(CO)(CCSD(T))/r(CO)(DFT) correlation.