Spin Signature of Nonlocal Correlation Binding in Metal-Organic Frameworks.

We develop a proper nonempirical spin-density formalism for the van der Waals density functional (vdW-DF) method. We show that this generalization, termed svdW-DF, is firmly rooted in the single-particle nature of exchange and we test it on a range of spin systems. We investigate in detail the role of spin in the nonlocal correlation driven adsorption of H_{2} and CO_{2} in the linear magnets Mn-MOF74, Fe-MOF74, Co-MOF74, and Ni-MOF74. In all cases, we find that spin plays a significant role during the adsorption process despite the general weakness of the molecular-magnetic responses. The case of CO_{2} adsorption in Ni-MOF74 is particularly interesting, as the inclusion of spin effects results in an increased attraction, opposite to what the diamagnetic nature of CO_{2} would suggest. We explain this counterintuitive result, tracking the behavior to a coincidental hybridization of the O p states with the Ni d states in the down-spin channel. More generally, by providing insight on nonlocal correlation in concert with spin effects, our nonempirical svdW-DF method opens the door for a deeper understanding of weak nonlocal magnetic interactions.

Analysis of the Accuracy of CAM-type Deformity Resection on a Low-cost Arthroscopic Simulator in a Training Scenario.

Objective To evaluate surgeons' performance in resecting CAM-type deformities using a realistic arthroscopic surgery simulator. Methods An arthroscopic simulator was created using low-cost materials with the help of a GTMax Core A1 3D printer and the programs Invesalius and Meshmixer 2017, which were used to develop femoral head parts in ABS material, with the presence of a CAM-type deformity, to mimic a femoroacetabular impact situation. After the operations were performed by 16 surgeons, the femurs were compared to a previous model with deformity and another without, using Cloudcompare, and parameters such as the volumetric difference between the operated femurs, with and without deformity, the minimum and maximum distance between them, the percentage of the deformity resected, the estimated time for total resection of the deformity, as well as a qualitative analysis based on the images and graphs provided by the program representing the areas of the parts resected, were evaluated at the end. Results The average resection speed was 34.66 mm 3 /min (SD = 46 mm 3 /min, max = 147.33; min = -2.66). The average resection rate was 26.2% (SD = 34.7%, max = 111; min = -2). Qualitative analysis showed hyporesection of deformities and sometimes hyperresection of nondeformed areas. The simulator was highly rated by the surgeons, with a tactile sensation very similar to real surgery, according to them. Conclusion Arthroscopic simulators have proved very useful in training less experienced surgeons.

Hip arthroscopy for femoroacetabular impingement in patients aged 50 years or older.

PURPOSE: The purpose of this study was to investigate outcomes after hip arthroscopy in a consecutive series of patients aged 50 years or older and determine how long patients avoided total hip replacement. METHODS: Between 2006 and 2008, prospectively collected data were retrieved from our database on 153 patients aged 50 years or older undergoing hip arthroscopy for femoroacetabular impingement. Data collected included range of motion, Modified Harris Hip Score (MHHS), Hip Outcome Score (HOS) for activities of daily living, HOS for sports, and Short Form 12 score. Survivors were defined as patients not requiring total hip replacement (THR). Survivorship was analyzed by use of the Kaplan-Meier method. RESULTS: THR was required after the arthroscopic treatment in 20% of patients (31 of 153). At 3 years (with data available in 64 patients), patients with greater than 2 mm of joint space had survivorship of 90% whereas those with 2 mm or less had survivorship of 57% (P = .001). In the patients who did not require THR, the MHHS improved from 58 to 84. The HOS for activities of daily living improved from 66 to 87 (P = .001), and the HOS for sports improved from 42 to 72 (P = .001). The physical component of the Short Form 12 improved from 38 to 49 (P = .001), whereas the mental component did not change (54 preoperatively v 53 postoperatively, P = .53). Median patient satisfaction was 9. CONCLUSIONS: On the basis of early results, patients with greater than 2 mm of joint space can expect improvement over preoperative status in pain and function after hip arthroscopy for femoroacetabular impingement. In patients aged 50 years or older with 2 mm of joint space or less and low preoperative MHHSs, early conversion to THR was seen. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Epidemiology and costs of surgical treatment of developmental dysplasia of hip in the Brazilian Public Health System in a decade.

OBJECTIVE: To describe and analyze the epidemiology and costs of surgical treatment of hip dysplasia in the Brazilian Public Health System. METHODS: An ecological analytical study that evaluated a time series and the geographic distribution of surgical treatment of hip dysplasia in Brazil. Frequencies of cases, number of cases and associated factors were analyzed. Correlations, frequency maps and flow maps are presented and discussed. RESULTS: During the study, 14,584 patients with dysplasia were admitted to hospitals according to Information Technology Department of the Public Health System. Patients underwent hospital treatment specific for dysplasia in 8,592 cases (at an average cost of R$ 2.225,50, total cost of R$ 19.124.086,25- updated values). In this group, mortality rate was 0.046% and mean hospitalization time was 4.41 days (standard deviation of 2,39 days). Age between 1 and 4 years (37.7%), female sex (64.5%) and white race (46%) were more frequent. Greater rates of specialists (R²=0.82; p<0.001), greater proportion of counties with high/very high human development index (R²=0.79; p<0.001), and higher per capita income (R²=0.68; p<0.001) correlated to greater rates of treatments undertaken per 1,000 live births (as per State of treatment). The factor most related to treatment rate per 1,000 live births (as per State of residence) was white race (R²=0.90; p<0.001). Southern states had higher treatment rates (as per State of residence, rate of 0.73/1,000), and Southeast states had greater absolute frequency of cases (46.7%) and greater flow of patients. CONCLUSION: The surgical treatment of hip dysplasia in Brazil occurs frequently, at relevant costs, and is distributed in a heterogenous and unequal fashion in the Public Health System. Southern states have a higher incidence of cases, and there is an association with racial and socioeconomic factors. There was no large variation in the incidence of cases over time.

Protocol of BRICS: Brazilian multicentric pragmatic randomised trial of surgical interventions for displaced diaphyseal clavicle fracture study: MIPO versus ORIF for the treatment of displaced midshaft clavicle fractures.

INTRODUCTION: Fractures of the diaphysis of the clavicle are common; however, treatment guidelines for this condition are lacking. Surgery is associated with a lower risk of non-union and better functional outcomes but a higher risk of complications. Open reduction and internal fixation with plates and screws are the most commonly performed techniques, but they are associated with paraesthesia in the areas of incisions, extensive surgical exposure and high rates of implant removal. Minimally invasive techniques for treating these fractures have a lower rate of complications. The aim of this study is to evaluate which surgical treatment option (minimally invasive osteosynthesis or open reduction and internal fixation) has better prognosis in terms of complications and reoperations. METHODS AND ANALYSIS: The study proposed is a multicentric, pragmatic, randomised, open-label, superiority clinical trial between minimally invasive osteosynthesis and open reduction and internal fixation for surgical treatment of patients with displaced fractures of the clavicle shaft. In the proposed study, 190 individuals with displaced midshaft clavicle fractures, who require surgery as treatment, will be randomised. The assessment will occur at 2, 6, 12, 24 and 48 weeks, respectively. The primary outcome of the study will be the number of complications and reoperations. For sample size calculation, a moderate effective size between the techniques was considered in a two-tailed test, with 95% confidence and 90% power. Complications include cases of infection, hypertrophic scarring, non-union, refracture, implant failure, hypoesthesia, skin irritation and shoulder pain. Reoperations are defined as the number of surgeries for pseudoarthrosis, implant failure, infection and elective removal of the implant. ETHICS AND DISSEMINATION: Study approved by the institutional ethics committee (number 34249120.9.0000.5505-V.3). The results will be disseminated by publications in peer-reviewed journals and presentations in medical meetings. TRIAL REGISTRATION NUMBER: RBR-3czz68)/UTN U1111-1257-8953.

Do complications in hip arthroscopy change with experience?

PURPOSE: The aim of this study was to evaluate the type and incidence of complications during the development of hip arthroscopic techniques. METHODS: A retrospective series of 194 files of patients treated with hip arthroscopy in a tertiary hospital from December 1999 to March 2008 was reviewed for complications. The incidence of complications was recorded consecutively for each group of 30 patients and in intervals of 2 years. A comparison between the complication rates was performed within the time frames and the set of cases. The type and severity of complications were also recorded. RESULTS: There were 12 complications (6.1%) in this series. Of these, 5 were neurologic (2.6%), 4 were musculoskeletal (2%), and 3 were vascular/ischemic (1.5%). According to severity, 2 were considered major complications (1%), 8 were intermediate (4.1%), and 2 were minor (1%). The incidence of complications did not change with time (P = .959) or with the number of cases performed (P = .771), but different types of complications occurred along the learning curve. CONCLUSIONS: The nature of complications changed with experience, but no significant variation in the incidence was observed over the 9-year period of experience with hip arthroscopy. LEVEL OF EVIDENCE: Level IV, therapeutic case series.

Three-Dimensional Digital Surgical Planning and Rapid Prototyped Surgical Guides in Bernese Periacetabular Osteotomy.

Bernese periacetabular osteotomy (PAO) developed by Ganz is currently the treatment of choice for skeletally mature symptomatic patients with developmental dysplasia of the hip (DDH) without osteoarthritis. However, the steep learning curve and considerable number of severe complications lead surgeons to seek for alternatives to promote greater reproducibility and safety of this procedure. This is a report of a DDH case surgically treated with the aid of a digital three-dimensional (3D) planning and rapidly prototyped sterile ABS plastic osteotomy guide, developed in Brazil. We present details regarding the planning, guide production, and surgical technique and report the early results of this treatment approach in a single patient. Digital 3D planning and rapidly prototyped surgical guides are applicable and helpful in PAO surgery as shown in this case. We noted no safety issues, good accuracy, and low production costs with this approach.

A density functional for sparse matter.

Sparse matter is abundant and has both strong local bonds and weak nonbonding forces, in particular nonlocal van der Waals (vdW) forces between atoms separated by empty space. It encompasses a broad spectrum of systems, like soft matter, adsorption systems and biostructures. Density-functional theory (DFT), long since proven successful for dense matter, seems now to have come to a point, where useful extensions to sparse matter are available. In particular, a functional form, vdW-DF (Dion et al 2004 Phys. Rev. Lett. 92 246401; Thonhauser et al 2007 Phys. Rev. B 76 125112), has been proposed for the nonlocal correlations between electrons and applied to various relevant molecules and materials, including to those layered systems like graphite, boron nitride and molybdenum sulfide, to dimers of benzene, polycyclic aromatic hydrocarbons (PAHs), doped benzene, cytosine and DNA base pairs, to nonbonding forces in molecules, to adsorbed molecules, like benzene, naphthalene, phenol and adenine on graphite, alumina and metals, to polymer and carbon nanotube (CNT) crystals, and hydrogen storage in graphite and metal-organic frameworks (MOFs), and to the structure of DNA and of DNA with intercalators. Comparison with results from wavefunction calculations for the smaller systems and with experimental data for the extended ones show the vdW-DF path to be promising. This could have great ramifications.

Comparative Study of Function and Quality of Life in Patients with Fracture of the Tibial Plateau Operated with Locked or Conventional Plates.

OBJECTIVE: To compare clinical, functional, and quality of life outcomes between patients with tibial plateau fractures operated with locked or conventional plates, and to compare the costs of these implants. METHODS: This was a comparative cross-sectional study of a consecutive series of patients with tibial plateau fractures treated surgically from August 2015 to June 2016. Patients < 18 years old, those unable to answer the questionnaires or to attend the outpatient reassessment, polytrauma patients, those with associated injuries on the ipsilateral limb, and patients who had not undergone treatment with bone plates were excluded. The present study compared the costs of the implants for the hospital, quality of life (with the 12-Item Short Form Health Survey [SF-12]), Lysholm score, pain scale, and clinical and radiological parameters. RESULTS: A total of 45 patients with tibial plateau fractures were admitted, and 11 cases were excluded. Two cases were lost to follow-up; therefore, 32 remained for the analysis (94%). The mean follow-up time was of 15.1 months (standard deviation [SD] = 4.8 months). In group A (locked plates), there were 22 patients (69%), at an average hospital cost of BRL 4,125.39/patient (SD = 1,634.79/patient) for the implants. In group B (conventional plates) there were 10 patients (31%), at an average cost of BRL 438.53 (SD = 161.8/patient) ( p < 0.00001). For the other parameters, no differences were observed, except for a greater articular depression in group A (2.7 mm ± 3.3 mm versus 0.5 mm ± 1.6 mm; p = 0.02; TE = 0.90). CONCLUSION: The costs of locked implants for the treatment of tibial plateau fractures are significantly higher than those of conventional implants, without any clinical, quality of life, radiological, or functional advantages of the locked implants demonstrated in the present series.

Reinventing the wheel: comparison of two wheel cage styles for assessing mouse voluntary running activity.

Voluntary wheel cage assessment of mouse activity is commonly employed in exercise and behavioral research. Currently, no standardization for wheel cages exists resulting in an inability to compare results among data from different laboratories. The purpose of this study was to determine whether the distance run or average speed data differ depending on the use of two commonly used commercially available wheel cage systems. Two different wheel cages with structurally similar but functionally different wheels (electromechanical switch vs. magnetic switch) were compared side-by-side to measure wheel running data differences. Other variables, including enrichment and cage location, were also tested to assess potential impacts on the running wheel data. We found that cages with the electromechanical switch had greater inherent wheel resistance and consistently led to greater running distance per day and higher average running speed. Mice rapidly, within 1-2 days, adapted their running behavior to the type of experimental switch used, suggesting these running differences are more behavioral than due to intrinsic musculoskeletal, cardiovascular, or metabolic limits. The presence of enrichment or location of the cage had no detectable impact on voluntary wheel running. These results demonstrate that mice run differing amounts depending on the type of cage and switch mechanism used and thus investigators need to report wheel cage type/wheel resistance and use caution when interpreting distance/speed run across studies. NEW & NOTEWORTHY The results of this study highlight that mice will run different distances per day and average speed based on the inherent resistance present in the switch mechanism used to record data. Rapid changes in running behavior for the same mouse in the different cages demonstrate that a strong behavioral factor contributes to classic exercise outcomes in mice. Caution needs to be taken when interpreting mouse voluntary wheel running activity to include potential behavioral input and physiological parameters.

Mixed-type femoroacetabular impingement associated with subspine impingement: recognizing the trifocal femoropelvic impingement.

To describe the arthroscopic surgical technique for subspine impingement (SSI) of the anterior inferior iliac spine (AIIS) associated with mixed type femoroacetabular impingement (FAI), through two standard arthroscopic portals (anterolateral and distal mid-anterior) in two patients with trifocal impingement. The authors report the cases of two young male patients, aged 32 and 36 years old, with trifocal femoropelvic impingement (TFPI). The technique consists of segmental capsulectomy, arthroscopic dissection of the AIIS, partial release of the direct head of the rectus femoris, resection of the AIIS projection with a burr and with fluoroscopic aid, correction of the pincer deformity, repair of the labrum with bioabsorbable anchors, and femoral osteoplasty. Details of the diagnostic workup and of the surgical technique are provided and discussed. In these cases, full range of motion was regained after surgery, as well as complete relief of pain, which was sustained in the last follow-up, one year post-operatively. Radiographs show adequate correction of the deformities in all three impingement sites. Simultaneous correction of the three sites (cam, pincer, and subspinal) provided full relief of symptoms and allowed return to work and sports. The authors propose that when approaching the symptomatic SSI, the possibility of concomitant FAI should always be considered and, in those cases, the approach must be comprehensive.

O objetivo deste trabalho foi descrever a abordagem cirúrgica artroscópica do impacto subespinhal (ISE) da espinha ilíaca anteroinferior (EIAI) associado ao impacto femoroacetabular (IFA) misto, por meio de dois portais artroscópicos padrão (anterolateral e medioanterior distal) em pacientes com impacto trifocal. Os autores relatam os casos de dois pacientes do sexo masculino, de 32 e 36 anos, com impacto femoropelvico trifocal (IFPT). A técnica consiste na ressecção segmentar da cápsula, dissecção artroscópica da EIAI com liberação parcial do reto femoral, osteoplastia com ressecção da proeminência com lâmina óssea e auxílio radioscópico, correção do pincer, reparo da lesão condrolabial com âncoras e osteoplastia femoral. Detalhes sobre o diagnóstico e a técnica são apresentados e discutidos. Nos casos operados, foi observada recuperação do arco de movimento normal do quadril e ausência de dor, que se mantiveram por um ano pós-operatório. Radiografias demonstram boa correção dos três focos de impacto em ambos os pacientes. A simultânea correção do IFPT nos seus três componentes (came, pincer e subespinhal) promoveu alívio completo dos sintomas e o retorno ao trabalho e aos esportes. Propõe-se que, na abordagem do ISE sintomático, sempre seja considerada a possibilidade da presença de IFA associado; nesses casos, a abordagem deve ser completa.

Parental awareness and perception for correct use of child restraint systems and airbags in Brazil.

OBJECTIVE: The objective of this study was to obtain information about the current knowledge and habits of parents who transport children in cars in Brazil. METHODS: A cross-sectional survey was conducted using specifically designed self-report questionnaires to parents of children attending a private pediatric office in a town in southwest Brazil. Data were collected regarding children's age, gender, height, and weight and possession of an automobile child restraint system (CRS), its type, frequency and adequacy of use, and reasons for not possessing or not using the devices. Parents were asked whether their cars were equipped with airbags and about the use of the restraints in seats with airbags. RESULTS: We interviewed parents of 293 children transported in cars who met the criteria for use of a CRS. Children were younger than 1 year in 15.3% of the cases, between 1 and 4 years in 38.6%, and older than 4 in 46.1%. Cars were equipped with CRS in 78.5% of the cases, but in only 58% of the cases was the device proper for child's age and adequately installed in the seat. Among owners of the devices, 84.3% reported that they always used it. Reasons for infrequency were forgetting the device at home or in another car (6.4%), the child disliking the device (3.2%), or the false impression that the child was grown enough not to use it (3.2%)l 87.1% did not justify why they did not always use the CRS. Considering type of CRS, correct installation of the seat, and frequency of use, only 44.4% of children under 1 year, 69.9% of those 1 to 4 years, and 52.6% over age 4 were protected. Only 28.6% of the parents knew that children should never be positioned in a seat with active airbags. CONCLUSION: Considering appropriateness for age, correctness of installation (in the back seat in the correct orientation), and frequency of use, only 50.85% (149/293) of the children were reported as always protected with a CRS. Children between 1 and 4 years were more likely to always use a CRS in this Brazilian survey. We were also able to identify an important gap in the knowledge about airbags among parents. Further efforts are needed to correct those distortions.

Pacemaker Implants in Children and Adolescents with Chagas Disease in Brazil: 18-Year Incidence.

BACKGROUND:: Chagas disease continues to be a serious public health problem, and accounts for 25-30% of the indications for cardiac stimulation in Brazil. OBJECTIVE:: To assess clinical and epidemiological characteristics of patients with Chagas disease, younger than 18 years, who had undergone pacemaker implantation in Brazil between 1994 and 2011, and its temporal trend. METHODS:: This was a cross-sectional analysis of data from the Brazilian Pacemaker Registry database. The following variables were analyzed: year when pacemaker was implanted, location, age, sex, ethnic group, functional class and the main electrocardiographic findings at baseline. RESULTS:: In a total of 183,123 implants performed between 1994 and 2011, 214 implants of cardiac stimulation device in Chagas disease patients aged younger than 18 years were identified. Mean age at implantation was 5.6 ± 6.2 years. Second- and third-degree atrioventricular blocks corresponded to 71% of indications for pacemaker implantation. Fifty-six percent of the procedures were performed in the southeast region. Regarding the total number of pacemaker implants per year, there was a remarkable increase in the implants for all causes. However, time series analysis of the implants in Chagas disease patients younger than 18 years revealed a significant reduction in the annual number of implants. CONCLUSION:: There has been an important reduction in the number of pacemaker implantations among children and adolescents with Chagas disease, suggesting a reduction in the vertical transmission of the parasite. FUNDAMENTO:: A doença de Chagas mantém-se como sério problema de saúde pública e tem sido responsável por aproximadamente 25% a 30% das indicações de estimulação cardíaca no Brasil. OBJETIVO:: Estudar as características clínicas e epidemiológicas dos pacientes menores de 18 anos portadores de doença de Chagas submetidos a implante de marca-passo no território brasileiro entre 1994 e 2011, e sua tendência temporal. MÉTODOS:: Trata-se de um estudo retrospectivo que utilizou informações coletadas pelo Registro Brasileiro de Marca-passo. As variáveis analisadas foram: ano do implante, localidade, idade, sexo, grupo étnico dos pacientes; classificação funcional e os principais achados eletrocardiográficos de base. RESULTADOS:: Em um total de 183 123 implantes realizados entre 1994 e 2011, foram identificados 214 implantes de dispositivos de estimulação cardíaca em portadores de doença de Chagas com idade inferior a 18 anos. A média de idade no momento do implante foi de 5,6 ± 6,2 anos. Bloqueios atrioventriculares de 2º e 3º graus foram responsáveis por 71% das indicações. Dos procedimentos, 55,6% foram realizados na região sudeste. Em relação ao total de implantes de marca-passo por ano, observamos um aumento importante e significante de implante por todas as causas. Entretanto, quando avaliamos a série temporal de implantes em pacientes com doença de Chagas menores que 18 anos, observamos uma redução expressiva e significativa no número anual de implantes. CONCLUSÃO:: Observa-se uma redução importante do número de implantes de marca-passo em crianças e adolescente chagásicos, o que sugere uma redução da transmissão vertical do parasita.

Primary and secondary osteoporotic fractures prophylaxis: evaluation of a prospective cohort.

OBJECTIVE: To measure the prevalence of primary drug prevention of fractures due to osteoporosis in patients admitted to a tertiary teaching hospital, in a medium-sized city, admitted with osteoporotic fractures. Moreover, to identify the incidence of prescribing secondary prophylaxis after the first fracture event. At the same time, the prevalence of risk factors for such fractures as described in the literature was measured. METHODS: This longitudinal prospective study was based on a cohort of patients admitted in a tertiary teaching hospital from October 2015 to January 2016. Patients with low energy or fragility fractures were included in the study regardless of gender or race, over the age of 50 years. All patients who did not have these characteristics were excluded. The follow-up lasted four months. Serial questionnaires were applied at admission and in the follow-up consultations at four to eight weeks and at 16 weeks. RESULTS: Only one patient reported receiving treatment with specific drugs for the disease before hospital admission, resulting in a prevalence of primary chemoprophylaxis of only 2.27%. No patient was prescribed medication for the treatment of osteoporosis after the fracture. The prevalence of risk factors was similar to those found in the literature review. CONCLUSION: In the present study, the frequency of primary and secondary osteoporosis chemoprophylaxis in patients who were admitted with fragility fractures was low, as well as the early indication of drug treatment after the first fracture. The prevalence of fragility fracture risk factors is similar to those reported in the literature.

OBJETIVO: Medir a prevalência da profilaxia medicamentosa primária de fraturas por osteoporose em pacientes internados em um hospital terciário de ensino, em uma cidade de médio porte, admitidos com fraturas osteoporóticas. Além disso, identificar a incidência de prescrição de profilaxia medicamentosa secundária após o evento da primeira fratura. Paralelamente, medimos a prevalência de fatores de risco para fratura por osteoporose descritos na literatura. MÉTODO: Estudo longitudinal de uma coorte prospectiva de pacientes admitidos em hospital terciário de ensino de outubro de 2015 a janeiro 2016. Foram incluídos pacientes com fraturas de baixa energia ou por fragilidade, independentemente do gênero ou etnia, acima de 50 anos. Todos os pacientes que não apresentavam essas características foram excluídos. O seguimento foi de quatro meses. Foram aplicados questionários seriados na admissão, no retorno com quatro a oito semanas e com 16 semanas. RESULTADO: Somente um paciente referiu ter recebido tratamento com drogas específicas para a doença antes da internação hospitalar, o que revela uma prevalência de quimioprofilaxia primária de apenas 2,27%. Nenhum paciente recebeu prescrição para tratamento da osteoporose após a fratura. A prevalência dos fatores de risco de fratura se assemelha àquela encontrada na literatura. CONCLUSÃO: A frequência de quimioprofilaxia primária e secundária da osteoporose em pacientes admitidos com fraturas por fragilidade é baixa em nosso meio, assim como a indicação precoce de tratamento medicamentoso após a primeira fratura. A prevalência dos fatores de risco de fratura por fragilidade é semelhante àquela citada na literatura.

Identification of the t-type calcium channel (Ca(v)3.1d) in developing mouse heart.

During cardiac development, there is a reciprocal relationship between cardiac morphogenesis and force production (contractility). In the early embryonic myocardium, the sarcoplasmic reticulum is poorly developed, and plasma membrane calcium (Ca(2+)) channels are critical for maintaining both contractility and excitability. In the present study, we identified the Ca(V)3.1d mRNA expressed in embryonic day 14 (E14) mouse heart. Ca(V)3.1d is a splice variant of the alpha1G, T-type Ca(2+) channel. Immunohistochemical localization showed expression of alpha1G Ca(2+) channels in E14 myocardium, and staining of isolated ventricular myocytes revealed membrane localization of the alpha1G channels. Dihydropyridine-resistant inward Ba(2+) or Ca(2+) currents were present in all fetal ventricular myocytes tested. Regardless of charge carrier, inward current inactivated with sustained depolarization and mirrored steady-state inactivation voltage dependence of the alpha1G channel expressed in human embryonic kidney-293 cells. Ni(2+) blockade discriminates among T-type Ca(2+) channel isoforms and is a relatively selective blocker of T-type channels over other cardiac plasma membrane Ca(2+) handling proteins. We demonstrate that 100 micromol/L Ni(2+) partially blocked alpha1G currents under physiological external Ca(2+). We conclude that alpha1G T-type Ca(2+) channels are functional in midgestational fetal myocardium.

Crystal structure of decameric 2-Cys peroxiredoxin from human erythrocytes at 1.7 A resolution.

BACKGROUND: The peroxiredoxins (Prxs) are an emerging family of multifunctional enzymes that exhibit peroxidase activity in vitro, and in vivo participate in a range of cellular processes known to be sensitive to reactive oxygen species. Thioredoxin peroxidase B (TPx-B), a 2-Cys type II Prx from erythrocytes, promotes potassium efflux and down-regulates apoptosis and the recruitment of monocytes by endothelial tissue. RESULTS: The crystal structure of human decameric TPx-B purified from erythrocytes has been determined to 1.7 [corrected)] A resolution. The structure is a toroid comprising five dimers linked end-on through predominantly hydrophobic interactions, and is proposed to represent an intermediate in the in vivo reaction cycle. In the crystal structure, Cys51, the site of peroxide reduction, is oxidised to cysteine sulphinic acid. The residue Cys172, lies approximately 10 A away from Cys51 [corrected]. CONCLUSIONS: The oxidation of Cys51 appears to have trapped the structure into a stable decamer, as confirmed by sedimentation analysis. A comparison with two previously reported dimeric Prx structures reveals that the catalytic cycle of 2-Cys Prx requires significant conformational changes that include the unwinding of the active-site helix and the movement of four loops. It is proposed that the stable decamer forms in vivo under conditions of oxidative stress. Similar decameric structures of TPx-B have been observed by electron microscopy, which show the protein associated with the erythrocyte membrane.

Effects of retinoic acid on plasminogen activator and mitogenic responses of cultured mouse cells.

Treatment of simian virus 40-transformed 3T3 cells with 1 microM beta-all-trans-retinoic acid (RA) resulted in a 5- to 6-fold enhancement of plasminogen activator (PA) release. Intracellular PA levels rose to twice control levels. Confluent 3T3 cells were less responsive to RA. In 6 of 10 experiments, no increase in 3T3 cell PA levels was noted, although up to a 2.5-fold enhancement of PA elaboration has been observed in some experiments at a dose of 10 microM RA. Simultaneous treatments of 3T3 cells with 10 microM RA and 2.1 to 9.3 mM Ca2+, 5 to 40 ng phorbol myristate acetate per ml, or 150 to 600 ng Fraction I from lactalbumin hydrolysate (Fl) protein per ml indicated that RA potentiated the PA stimulatory activities of these agents. Extracellular PA levels of RA-treated cells increased by 4 to 10 times the amount of increase observed for Ca2+, PMA, or Fl alone. A potentiating activity of RA was also evident when quiescent 3T3 cells were pretreated with 10 microM RA and then stimulated to synthesize DNA with Ca2+, PMA, or Fl. For RA-pretreated cells, an increased percentage of nuclei was labeled with [3H]thymidine (24 hr) in response to doses of the three mitogens which were ineffective without RA pretreatment (2.4mM Ca2+, 5 ng PMA per ml, or 150 ng Fl protein per ml). Additional experiments have indicated that, like platelet extracts, Ra renders quiescent 3T3 cells competent to synthesize DNA in response to the progression factors of human plasma as defined by Pledger et al. (Proc. Natl. Acad. Sci. U. S. A., 74: 4481-4485, 1977). Pretreatment of quiescent 3T3 cells for 6 hr with 10 microM RA resulted in a greater than 4-fold increase in the percentage of cells which incorporated [3H]thymidine in response to a 36-hr treatment with 10% human plasma, as compared to cells treated with human plasma alone. Thus, under certain conditions, RA may have cell-activating properties, and caution should be exercised with regard to its suggested use as an antitumor agent.

Correlation between activation of quiescent 3T3 cells by retinoic acid and increases in uridine phosphorylation and cellular RNA synthesis.

Short exposure of cultured quiescent cells to micromolar quantities of beta-all-trans-retinoic acid (RA) has been reported to potentiate the effects of phorbol myristate acetate in promoting the transition from the resting to growing states of these cells. Longer periods of exposure to RA result in substantial inhibition of cellular proliferation. We now show that short-term treatment of quiescent Swiss 3T3 cells with RA yields marked increases in uridine phosphorylation and total cellular RNA synthesis as well as 2-deoxyglucose uptake. Upon subsequent treatment of the cells with phorbol myristate acetate, a direct correlation between the comitogenic activity of RA and its stimulation of uridine phosphorylation and RNA synthesis is apparent. The increases in 2-deoxyglucose uptake persist after long-term exposure of the cells to RA when the growth-inhibitory effects of this agent are observed.