Magnetism in a 2D Hybrid Ruddlesden-Popper Perovskite through Charge Redistribution Driven by an Organic Functional Spacer

Two-dimensional Ruddlesden-Popper (RP) perovskites are emerging materials offering great synthetic versatility and remarkable features due to the tunability of their crystal structure. We present a novel strategy to provide magnetism in a 2D RP perovskite using histidine molecules as a spacer, which could induce charge rebalancing at the interface of the inorganic layer. We observe that the amide and imidazole groups are close to Pb ions. The interaction with the imidazole indicates that this functional group, possibly assisted by the carboxyl close to the vicinity of the amine terminal, is inducing charge rearrangement from Pb²⁺ to paramagnetic Pb³⁺ ions, resulting in a positive magnetic moment. This magnetized 2D hybrid perovskites can be classified as a novel class of promising materials showing a magnetic moment at their interface, which may result in intriguing physical properties due to a delicate balance between magnetism and a quantum well confinement effect in the inorganic layer.

Integrated quality assessment for diabetes care in Portuguese primary health care using prevention quality indicators

AIMS

This study evaluates the prevention quality indicators (PQI) for Diabetes Mellitus (DM) in Portugal using contemporary data and explores their variability according to Primary Health Care (PHC) quality indicators.

METHODS

We conducted a retrospective observational analysis of secondary data comprising Portuguese PHC indicators by health centres group (ACES) and the National Hospital Morbidity Database. We calculated and analysed age-sex-adjusted rates for each PQI. Worse-performing ACES were identified using the 2017 median PQI values as an assessment cut-off. A multivariate logistic analysis was carried to find variables associated with the likelihood of being a worse-performing ACES for the biennium.

RESULTS

The median values of the indicator PQI93 - Prevention Quality Diabetes Composite were 79 and 65.2 hospitalizations per 100 000 pop, in 2016 and 2017 respectively. Diabetes long term complications (PQI 03) accounted for most of the hospitalizations. The quality indicator in PHC with greater influence on PQI93 was the proportion of DM patients with <65 years with test results for HbA1c < = 6.5%.

CONCLUSIONS

This study shows that some PHC quality indicators are closely related to DM care, and so their monitoring is of high importance. Diabetes long term complications (PQI 03) demand greater attention from PHC professionals.

Primary care organizational model mix and avoidable hospitalization: an ecological study in Portugal

Background

In Portugal, there are different organizational models in primary health care (PHC), mainly regarding the payment scheme. USF-B is the only type with financial incentives to the professional (pay-for-performance). Our goal was to assess the relationship between groups of primary healthcare centres (ACES) with higher proportion of patients within USF-B model and the rate of avoidable hospitalizations, as proxy of primary care quality.

Methods

We conducted a cross-sectional study considering the 55 ACES from mainland Portugal, in 2017. We used data from public hospitalizations to calculate the prevention quality indicator (avoidable hospitalizations) adjusted for age and sex, using direct standardization. The main independent variable was the proportion of patients in one ACES registered in the USF-B model. Unemployment rate, proportion of patients with family doctor and presence of Local Health Unit (different organization model) within ACES were also considered. The association was assessed by means of a linear regression model.

Results

Age-sex adjusted PQI value varied between 490 and 1715 hospitalizations per 100,000 inhabitants across ACES. We observed a significant effect of the proportion of patients within USF-B in the crude PQI rate (p = 0.001). However, using the age-sex adjusted PQI, there was not a statistical significant association (p = 0.504). This last model was also adjusted for confounding variables and the association remains non-significant (p = 0.865).

Conclusions

Our findings suggest that, when adjusting for age and sex, there is no evidence that ACES with more patients enrolled in a pay-for-performance model is associated with higher quality of PHC (using avoidable hospitalizations as proxy). Further studies addressing individual data should be performed.

This work was financed by FEDER funds through the COMPETE 2020 - POCI, and by Portuguese funds through FCT in the framework of the project POCI-01-0145-FEDER-030766 “1st.IndiQare”.

Key messages

Adjusting PQI to sex and age seems to influence its value more than the type of organizational model of primary health care. Groups of primary healthcare centres with more units under the pay-for-performance scheme was not associated with different rate of avoidable hospitalizations.

Efficiency of groups of primary healthcare centres: a frontier analysis of primary care in Portugal

Background

Primary health care (PHC) is the cornerstone of several health systems. The Portuguese PHC is organized in five mainland regions (ARS), that oversee 55 local groups of primary healthcare centres (ACES). We assessed the efficiency of all 55 ACES in mainland Portugal, as well as organizational and socioeconomic determinants of the efficiency.

Methods

A cross-sectional non-parametric frontier analysis was performed for 2017. The first model included two inputs (i.e. number of physicians and number of nurses) and a single output (i.e. number of PHC visits), while the second model included an additional output, i.e. Prevention Quality Indicator (PQI) overall composite (avoidable hospitalizations) adjusted for age and sex - as undesirable output. In a second stage, a (multivariate) Tobit regression was used to assess organizational and socioeconomic determinants of efficiency.

Results

In the first model, only 8 ACES (14.5%) were on the efficiency frontier, while 25 ACES should readjust their human resource balance. In the second model, 9 ACES (16.4%) were considered efficient. When considering quality, one ACES previously considered inefficient moved to the frontier and two ACES lost their benchmark position. The second-stage analysis indicates that groups with a higher proportion of PHC units with pay-for-performance incentives were associated with higher efficiency.

Conclusions

Most ACES have the potential to improve their production levels., A better management of human resources can contribute to improve overall efficiency. ACES with a higher proportion of units with pay-for-performance schemes seem to be more efficient. These findings contribute to the evaluation of policies to integrate and scale up PHC services locally, such as the recent primary care networks in the NHS UK.

This work was financed by FEDER funds through the COMPETE 2020 - POCI, and by Portuguese funds through FCT in the framework of the project POCI-01-0145-FEDER-030766 “1st.IndiQare”.

Key messages

Most Portuguese ACES have the potential to improve their outputs given their current level of human resources. Local groups that aggregate more PHC units with pay-for-performance schemes are associated with high efficiency.

Time trends of primary care quality across Portuguese regions: using prevention quality indicators

Background

Primary care quality is one of the main dimensions of primary care performance and can be evaluated by several methods, e.g. studying hospitalizations for conditions that could be treated, or less severe, if appropriately managed in primary care. Accordingly, the Agency for Healthcare Research and Quality (AHRQ) developed prevention quality indicators (PQIs). In this study, we aimed to compare PQIs and their time trends across Portuguese regions.

Methods

We performed a retrospective study, using all adult public hospital discharges in mainland Portugal, between 2011 and 2015. PQI rates for the overall (PQI 90) and composite indicators (i.e. 91 - acute, 92 - chronic, 93 - diabetes) were computed using AHRQ specifications. These rates were compared between the 5 Portuguese NUTS 2 regions of residence.

Results

From the total of 407,792 hospital discharges in mainland Portugal (2011-2015) 11.9% comprised the selected PQIs, the majority related the acute composite PQI, followed by the chronic composite PQI. The hospitalization rate of the overall PQI increased from 999.5 hospitalizations (2011) to 1231,0 hospitalizations/100,000 inhabitants (2015), with an increase in all NUTS 2 regions. In 2015, while Algarve and North had the lowest PQI rates, Centro and Alentejo showed the highest ones.

Conclusions

Between 2011 and 2015, there was an increasing trend of overall and composite PQI rates. Also, important differences between Portuguese regions were found that must be further studied.

The authors thank the support given by the Project ’POCI-01-0145-FEDER-030766’ (1st.IndiQare - Quality indicators in primary health care: validation and implementation of quality indicators as an assessment and comparison tool), funded by Fundação para a Ciência e a Tecnologia (FCT) and co-funded by Fundo de Desenvolvimento Regional (FEDER) through Operacional Competitividade e Internacionalização (COMPETE 2020).

Key messages

Between 2011 and 2015, overall prevention quality indicator rate increased in Portugal. There are great differences between Portuguese NUTS 2 regions regarding prevention quality indicators.

Analysis of the effects of climate variables on Apis mellifera pollen foraging performance

ABSTRACT Pollination services performed by bees are essential for the reproduction of a great part of flowering plants. The pollen collected by Apis mellifera while performing pollination (bee pollen), has been incorporated into the human diet for its favorable nutritional components. Around 1,500 tons of bee pollen are produced annually worldwide, especially in Spain, China, Australia, Argentina, and Brazil. Despite the importance of bee pollen within apiculture, little is known about the effects of climate variations on bee pollen collection and production. We monitored the pollen collection performance of 24 different honey bee colonies in different climate conditions within a period of one year. We then analyzed the statistical interaction among the number of worker bees returning with pollen loads and 12 climatic variables, to produce a predictive mixed linear model. The results obtained showed that 7 climatic variables were statistically correlated to the pollen collection observed: Maximum temperature of the day, minimum temperature of the day, dew point temperature, relative humidity, cloud cover, rainfall, and the date of the sample. This research brings information for the development of a more effective pollen productive system.

Flint corn grain processing and citrus pulp level in finishing diets for feedlot cattle

Four trials were conducted to evaluate the effects of flint corn processing and the replacement of corn with citrus pulp (CiP) in diets for Nellore feedlot cattle. In a 103-d finishing trial, 216 Nellore bulls (350 ± 24 kg initial BW) were used in a randomized complete block design with a 2 × 4 factorial arrangement of treatments. Factors included 2 processing methods, either ground corn (GC) or steam-flaked corn (FC), with CiP replacing each corn type at 4 levels (0, 25, 50, and 75% of DM). All diets contained 12% sugarcane bagasse and 88% concentrate (DM basis). Treatments were also evaluated in metabolism trials, in which 10 ruminally cannulated Nellore steers (389 ± 37 kg) were assigned to 2 independent but simultaneous 5 × 5 Latin squares, each using 1 method of corn processing (GC and FC). Interactions ( < 0.05) between corn processing and CiP inclusion level were observed for final BW, DMI, ADG, G:F, and HCW. With FC-based diets, added CiP linearly decreased final BW ( = 0.04), whereas with GC-based diets, added CiP quadratically increased final BW ( = 0.002). With FC-based diets, the inclusion of CiP linearly increased DMI ( = 0.03) and linearly decreased ADG ( = 0.03) and G:F ( = 0.001). Increasing CiP in GC-based diets quadratically increased DMI ( = 0.001), ADG ( = 0.005), and HCW ( = 0.003). In FC-based diets, CiP inclusion had no effect on HCW ( = 0.21). Dressing percent, LM area, and 12th-rib fat were not affected by diet ( ≥ 0.05). For steers fed GC diets, CiP inclusion in the diet quadratically decreased the molar proportion of isovalerate ( = 0.001) but linearly increased ruminal butyrate ( = 0.006). No differences ( ≥ 0.16) were observed for total VFA concentrations, acetate:propionate ratio, and ruminal NH-N as CiP replaced GC. For steers fed FC diets, the molar proportion of acetate linearly increased ( = 0.002) whereas the proportion of propionate was linearly decreased ( < 0.001), resulting in a linear increase ( = 0.001) in the acetate:propionate ratio. Replacing corn with CiP linearly reduced NEm ( = 0.001) and NEg ( < 0.001) of FC-based diets but did not affect ( = 0.15) NE values of CG-based diets. Steam flaking flint corn improved cattle performance in this trial more than has been reported for dent corn in the published literature.

Differential performance of honey bee colonies selected for bee-pollen production through instrumental insemination and free-mating technique

ABSTRACT The use of bee-pollen as a nutritional supplement or as a production-enhancing agent in livestock has increased the demand for this product worldwide. Despite the current importance of this niche within the apiculture industry, few studies have addressed the pollen production. We tested the performance of free-mated (FM) and instrumentally inseminated queens (IQ) in order to establish the effect of different breeding systems on pollen production. The F1 generation of IQ queens produced 153.95±42.83g/day, showing a significant improvement on the pollen production (2.74 times) when compared to the parental generation (51.83±7.84g/day). The F1 generation of free-mated queens produced 100.07±8.23 g/day, which increased by 1.78 times when compared to the parental generation. Furthermore, we observed a statistically significant difference between the pollen production between colonies from the IQ and FM treatments. This study suggests that inseminated queens should be considered by beekeepers that aim to increase pollen production.

Hierarchically structured nanowires on and nanosticks in ZnO microtubes

We report both coaxial core-shell structured microwires and ZnO microtubes with growth of nanosticks in the inner and nanowires on the outer surface as a novel hierarchical micro/nanoarchitecture. First, a core-shell structure is obtained—the core is formed by metallic Zn and the semiconducting shell is comprised by a thin oxide layer covered with a high density of nanowires. Such Zn/ZnO core-shell array showed magnetoresistance effect. It is suggested that magnetic moments in the nanostructured shell superimposes to the external magnetic field enhancing the MR effect. Second, microtubes decorated with nanowires on the external surface are obtained. In an intermediate stage, a hierarchical morphology comprised of discrete nanosticks in the inner surface of the microtube has been found. Hyperfine interaction measurements disclosed the presence of confined metallic Zn regions at the interface between linked ZnO grains forming a chain and a ZnO thicker layer. Surprisingly, the metallic clusters form highly textured thin flat regions oriented parallel to the surface of the microtube as revealed by the electrical field gradient direction. The driving force to grow the internal nanosticks has been ascribed to stress-induced migration of Zn ions due to compressive stress caused by the presence of these confined regions.

Kohlschütter-Tönz syndrome in siblings without ROGDI mutation

BACKGROUND

Kohlschütter-Tönz syndrome is a rare neurodegenerative disorder presenting with intractable seizures, developmental regression, and characteristic hypoplastic dental enamel indicative of amelogenesis imperfecta. Recently, mutations in ROGDI were identified in part of Kohlschütter-Tönz syndrome cases, but the siblings reported here do not have a mutation in the ROGDI gene, showing that there is genetic heterogeneity in Kohlschütter-Tönz syndrome.

AIM

Report two siblings that have Kohlschütter-Tönz syndrome.

CONCLUSION

Early onset of seizures and lack of the ability to walk without support may be signs of non-ROGDI mutations in Kohlschütter-Tönz syndrome patients.

Coherent control of quantum fluctuations using cavity electromagnetically induced transparency

We study the all-optical control of the quantum fluctuations of a light beam via a combination of single-atom cavity quantum electrodynamics (CQED) and electromagnetically induced transparency (EIT). Specifically, the EIT control field is used to tune the CQED transition frequencies in and out of resonance with the probe light. In this way, photon blockade and antiblockade effects are employed to produce sub-Poissonian and super-Poissonian light fields, respectively. The achievable quantum control paves the way towards the realization of a prototype of a novel quantum transistor which amplifies or attenuates the relative intensity noise of a light beam. Its feasibility is demonstrated by calculations using realistic parameters from recent experiments.

Psychiatric readmission: an integrative review of the literature

BACKGROUND

In the global context of contemporary psychiatric deinstitutionalization, the phenomenon of psychiatric readmission imposes important challenges, as it exposes the fragility of the network of mental health services.

AIMS

To gather, synthesize and analyse the national and international scientific literature regarding the phenomenon of psychiatric readmission in the context of deinstitutionalization.

METHODS

Through the combination of descriptors, an integrative review was performed of publications from the period 1997 to 2010 included in the MedLine, PubMed, LILACS, SciELO and PsycINFO databases. Selection of the articles was based on pre-established inclusion and exclusion criteria. Three authors independently evaluated the eligibility of the articles. The level of inter-judge concordance was calculated, using the formula: agreement = Σ possible concordance subtracted from real discordance divided by the number of articles. Information about the selected studies was systematized and analysed.

FINDINGS

Sixteen articles met the inclusion criteria. Studies conducted and published in international journals, mainly in the USA, with a quantitative approach predominated. In general, the studies addressed the phenomenon of psychiatric readmission after the restructuring of mental health care. The variables investigated were clinical and sociodemographic factors and the characteristics of the mental health service associated with readmission, as well as the programs developed specifically for patients vulnerable to hospital readmissions.

CONCLUSIONS

It was noted that the perspective of the patient regarding their readmissions, as well as the interface with the social and familial context in which they maintain their social relationships and care for their health, was largely unexplored by the literature.

Scaling behavior of nearly first order magnetic phase transitions

A scaling behavior between heat capacity C*(P) and thermal expansion coefficient times temperature ΩTλ, where λ is a scale factor, is obtained for ferromagnetic La(1 - x)Ca(x)MnO(3) with x = 0.20, 0.25, 0.30, 0.34, 0.40, and 0.45 compounds. The pressure derivative of the magnetic phase transition temperature obtained through a scaling method is in good agreement with experimental results for all samples. The critical exponents associated with the specific heat (α) for x = 0.25, 0.30, and 0.34 are very close to the phase boundary where continuous phase transitions become discontinuous. This is attributed to strong coupling among the spin, charge, and lattice degrees of freedom, which indicates that the magnetization alone would be a poor choice for the order parameter in these systems. Based on thermodynamic arguments, a phase diagram with diverging, cusp-like, near first order, and first order phase transitions is presented.

A nationwide population-based study of migraine in Brazil

The aim of this study was to estimate the 1-year prevalence of migraine and the degree of the association of migraine with some sociodemographic characteristics of a representative sample of the adult population of Brazil. This was a cross-sectional, population-based study. Telephone interviews were conducted on 3848 people, aged 18-79 years, randomly selected from the 27 States of Brazil. The estimated 1-year gender- and age-adjusted prevalence of migraine was 15.2%. Migraine was 2.2 times more prevalent in women, 1.5 times more in subjects with > 11 years of education, 1.59 times more in subjects with income of < 5 Brazilian Minimum Wages per month, and 1.43 times more in those who do not do any physical exercise. The overall prevalence of migraine in Brazil is 15.2%. Migraine is significantly more prevalent in women, subjects with higher education, with lower income, and those who do not exercise regularly, independently of their body mass index.

Chronic Daily Headache in Brazil: A Nationwide Population-Based Study

The objectives of this study were to estimate the 1-year prevalence of chronic daily headache (CDH) and the degree of the association of CDH with some sociodemographic characteristics of the adult population of Brazil. This was a cross-sectional, population-based study. We conducted telephone interviews with 3848 people, aged 18-79 years, randomly selected from the 27 States of Brazil. The degree of the association was calculated through prevalence ratios, adjusted with Poisson regression by gender, age and some sociodemographic factors. The estimated 1-year gender- and age-adjusted prevalence of CDH was 6.9±. CDH was 2.4 times more prevalent in women, 1.72 times more in unemployed, 1.63 times more in subjects with high household income and two times greater in those who did not exercise. The overall prevalence of CDH in Brazil is high. CDH is significantly more prevalent in women, the unemployed, subjects with higher income, and in those who do not exercise.

Dimensional crossover in the purple bronze Li0.9Mo6O17

Thermal expansion of Li0.9Mo6O17 is a-axis dominated which reduces the separation of the conducting chains at low temperature enhancing the interchain coupling. This destabilizes the Luttinger-liquid fixed point leading to an electronic charge- (or spin-) density wave dominated by Coulomb repulsion, as predicted by theories for Luttinger liquids.

Method for analyzing second-order phase transitions: application to the ferromagnetic transition of a polaronic system

A new method for analyzing second-order phase transitions is presented and applied to the polaronic system La(0.7)Ca(0.3)MnO3. It utilizes heat capacity and thermal expansion data simultaneously to correctly predict the critical temperature's pressure dependence. Analysis of the critical phenomena reveals second-order behavior and an unusually large heat capacity exponent.

Hair mercury speciation as a function of gender, age, and body mass index in inhabitants of the Negro River basin, Amazon, Brazil

Human mercury contamination can be monitored through hair analysis of mercury's inorganic and organic form as methylmercury (Me-Hg). Hair total mercury and Me-Hg were studied in a Negro River fish-eating population in relation to age, gender, and body mass index (BMI). This riverbank population eats fish at least twice a day and is exposed to high levels of Me-Hg. Total mercury ranged from 1.51 microg/g to 59.01 microg/g, with only 21% of the sampled population having Hg concentration of less than 10 microg/g hair. The mean percentage of Me-Hg was 71.3% (range 34% to 100%) of the total mercury in hair. No statistically significant differences were found in regard to age groups (children and adults) or BMI. However, women had significantly lower total mercury in hair than men, but the percentage of Me-Hg was not significantly different. Women in fertile age (15-40 years) had hair total mercury ranging from 1.65-32.63 microg/g, and 65% in this subgroup had hair mercury above 10 microg/g hair. The percentage of Me-Hg concentration in hair of this freshwater, fish-eating population is comparable to populations eating ocean fish from different parts of the world and does not seem to be affected by age, gender, and BMI.

Evaluation of the areas of neuronal cell bodies and nuclei in the myenteric plexus of the duodenum of adult rats

This study compared the areas of cell body and nucleus profiles of the myenteric neurons in the antimesenteric and intermediate regions of the duodenum of adult rats. Five male rats were used. The duodenum was removed and dissected to whole-mount preparations, which were stained by the Giemsa technique. The areas of cell body and nucleus profiles of 100 neurons, 50 from each region, of each animal, were assessed with image analyser. Based on the global mean+/-SD of the areas of cell body profiles, neurons were labelled as small, medium or large. It was observed that the neurons did not differ significantly in size or incidence between the antimesenteric and intermediate regions. However, the nuclei of the small and medium neurons were significantly smaller in the latter region. It is discussed that the smaller nuclear size could be related to the cell bodies being slightly smaller on this region and to a possible smaller biosynthetic activity which would influence nuclear size.

Relationship between shock energy and postdefibrillation ventricular arrhythmias in patients with implantable defibrillators

BACKGROUND

The relationship between postdefibrillation ventricular arrhythmias and shock strength is poorly understood in patients with implantable defibrillators. The purpose of this study was to characterize the relationship between postdefibrillation ventricular arrhythmias and shock strength.

METHODS AND RESULTS

Forty-three patients with an implanted defibrillator underwent six separate inductions of ventricular fibrillation (VF) after a step-down defibrillation energy requirement (7.3 +/- 4.6 J) was determined. For each of the first three inductions of VF, the first two shocks were low energy and equal to approximately 75% of the defibrillation energy requirement (5.4 +/- 3.3 J), or to the defibrillation energy requirement plus 10 J (17.5 +/- 4.3 J). After the first two shocks, subsequent shocks were programmed to the maximum available energy (29.0 +/- 2.5 J). The alternate technique was used for the subsequent three inductions of VF. Postdefibrillation ventricular arrhythmias were noted. Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec were more frequent after a low-energy shock (19%), than after a high-energy shock (1.5%; P = 0.005). Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec were more frequent after a high-energy shock (32%), than after a low-energy shock (7.1%; P = 0.002). A relationship between the cycle length of the postdefibrillation ventricular arrhythmias and the absolute defibrillation energy was observed (P < 0.001; r = 0.6), and ventricular arrhythmias with a cycle length > 300 msec were uncommon after shocks < or = 10 J (P = 0.001). The characteristics of ventricular arrhythmias after maximum-energy shocks were similar to those that occurred after high-energy shocks.

CONCLUSIONS

Postdefibrillation ventricular arrhythmias with a cycle length < or = 300 msec are more common after shocks of strength associated with a low probability of successful defibrillation. Postdefibrillation ventricular arrhythmias with a cycle length of > 300 msec are more common after high- and maximum-energy shocks, and are directly related to the absolute defibrillation energy.

A technique for the rapid diagnosis of atrial tachycardia in the electrophysiology laboratory

OBJECTIVE

The purpose of this study was to determine if the atrial response upon cessation of ventricular pacing associated with 1:1 ventriculoatrial conduction during paroxysmal supraventricular tachycardia is a useful diagnostic maneuver in the electrophysiology laboratory.

BACKGROUND

Despite various maneuvers, it can be difficult to differentiate atrial tachycardia from other forms of paroxysmal supraventricular tachycardia.

METHODS

The response upon cessation of ventricular pacing associated with 1:1 ventriculoatrial conduction was studied during four types of tachycardia: 1) atrioventricular nodal reentry (n = 102), 2) orthodromic reciprocating tachycardia (n = 43), 3) atrial tachycardia (n = 19) and 4) atrial tachycardia simulated by demand atrial pacing in patients with inducible atrioventricular nodal reentry or orthodromic reciprocating tachycardia (n = 32). The electrogram sequence upon cessation of ventricular pacing was, categorized as "atrial-ventricular" (A-V) or "atrial-atrial-ventricular" (A-A-V).

RESULTS

The A-V response was observed in all cases of atrioventricular nodal reentrant and orthodromic reciprocating tachycardia. In contrast, the A-A-V response was observed in all cases of atrial tachycardia and simulated atrial tachycardia, even in the presence of dual atrioventricular nodal pathways or a concealed accessory atrioventricular pathway.

CONCLUSIONS

In conclusion, an A-A-V response upon cessation of ventricular pacing associated with 1:1 ventriculoatrial conduction is highly sensitive and specific for the identification of atrial tachycardia in the electrophysiology laboratory.

Lack of a relationship between serum ferritin levels and coronary atherosclerosis evaluated by coronary arteriography

Many clinical and epidemiological studies have demonstrated the relationship between serum ferritin and ischemic heart disease. In the present study we evaluated the relationship between coronary heart disease (CHD) and serum ferritin levels in patients submitted to coronary arteriography. We evaluated 307 patients (210 (68.7%) males; median age: 60 years) who were submitted to coronary angiography, measurement of serum ferritin and identification of clinical events of ischemic heart disease. Serum ferritin is reported as quartiles. Ninety-six patients (31.27%) had normal coronary angiography (group 1) and 211 (68.73%) had coronary heart disease (group 2). Of the patients with CHD, 61 (28.9%) had serum ferritin levels higher than 194 ng/ml (4th quartile), as opposed to only 14 (14.58%) of those without CHD (P = 0.0067). In the 2nd quartile, 39 patients (18.48%) had CHD, while 35 patients (36.46%) had normal coronary arteries (P = 0.00064). Multivariate analysis of the data showed that the difference between groups was not statistically significant (P = 0.33). We conclude that there is no independent relationship between coronary heart disease and increased levels of serum ferritin.

Comparative study for the identification of myocardial ischemia by contrast ventriculography under the effect of isosorbide mononitrate and by perfusional myocardial scintigraphy in patients with ischemic heart disease

OBJECTIVE

To evaluate and compare the usefulness of cineventriculographies, before and after nitrate use, to technetium-99m sestamibi scintigraphy for the identification of myocardial ischemia.

METHODS

Twenty-six patients were studied at basal conditions and 5 minutes after intravenous administration of isosorbide mononitrate (0.3 mg/kg), to evaluate the performance and regional wall motion of the left ventricle (LV). The results were compared too those obtained with technetium-99m sestamibi scintigraphy.

RESULTS

Before nitrate, contrast ventriculography identified 30 normal segments, 62 hypokinetic segments, 28 dyskinetic segments, and 14 akinetic segments. After drug administration, 99 segments were normal, 11 hypokinetic, 11 dyskinetic, and 13 akinetic. Myocardial scintigraphy revealed 110 ischemic segments and 18 fibrotic segments (p < 0.005). After drug administration, the ventriculography showed increase in the velocity of circumferential fiber shortening (p = 0.0142), the ejection fraction (p = 0.0462), decrease in the end-systolic volume (p = 0.0031) and no change in end-diastolic volume.

CONCLUSION

Contrast ventriculography using nitrate proved to be similar to perfusional myocardial scintigraphy in the identification of myocardial ischemia.

Cells isolated from adult human skeletal muscle capable of differentiating into multiple mesodermal phenotypes

Wound healing is the response of tissue to injury that results in scar formation. Tissue regeneration would be a more ideal response. Previously, we have isolated a population of cells from avian, rodent, and rabbit skeletal muscle capable of differentiating into multiple mesodermal phenotypes. The present experiments were designed to determine whether a similar population of cells exist in human skeletal muscle. Separate cell preparations from skeletal muscle on an amputated leg of a 75-year-old female and the pectoralis muscle of a 27-year-old male were enzymatically dissociated and cultured to confluence in Eagle's minimal essential medium with 10 per cent preselected horse serum, then trypsinized, filtered, and slowly frozen in 7.5 per cent dimethylsulfoxide to -80 degrees C. The cells were thawed and plated with the same media plus dexamethasone (a nonspecific differentiation agent) at 10(-10) - 10(-6) M concentrations for up to 6 weeks. Immunological and histochemical staining assays were performed. Phenotypes observed included stem cells with typical stellate morphology (control), skeletal myotubes (anti-myosin), smooth muscle (anti-a-actin), bone (von Kossa stain), cartilage (Alcec blue), and fat (Sudan black B). These experiments establish the existence of a population of mesenchymal stem cells in human skeletal muscle capable of differentiating into multiple mesodermal phenotypes. The possibility exists of manipulating the mesenchymal stem cells to achieve appropriate regeneration of mesenchymal tissues in the injured patient.

Effect of dietary fat on lymphocyte proliferation and metabolism

The effect of diets enriched with fat containing different fatty acids on glucose and glutamine metabolism of mesenteric lymph nodes lymphocytes, spleen, and thymus and lymphocyte proliferation was examined. The following fat-rich diets were tested: (1) standard chow (CC); (2) medium chain saturated fatty acids (MS)--coconut fat oil; (3) long chain saturated fatty acids (LS)--cocoa butter; (4) monounsaturated fatty acids (MU)--canola oil (n-9); (5) polyunsaturated fatty acids (PU)--soybean oil (n-6). Of the fat-rich diets tested, MS was the one to present the least pronounced effect. Lymphocyte proliferation was reduced by LS (64 per cent), MU (55 per cent), and PU (60 per cent). Hexokinase activity was enhanced in lymph node lymphocytes by PU (67 per cent), in the spleen by MS (42 per cent), and in the thymus by PU (30 per cent). This enzyme activity was reduced in the spleen (33 per cent) by LS and MU (35 per cent). In the thymus, this enzyme activity was reduced by LS (26 per cent) and MU (13 per cent). Maximal phosphate-dependent glutaminase activity was raised in lymphocytes by MS (70 per cent) and MU (20 per cent). This enzyme activity, however, was decreased in lymphocytes by PU (26 per cent), in the spleen by LS (15 per cent), and in the thymus by MU (44 per cent). Citrate synthase activity was increased in lymphocytes by MU (35 per cent), in the spleen by LS (56 per cent) and MU (68 per cent), and in the thymus by LS (42 per cent). This enzyme activity was decreased in lymphocytes by PU (24 per cent) only. [U-14C]-Glucose decarboxylation was raised by all fat-rich diets; MS (88 per cent). LS (39 per cent), MU (33 per cent), and PU (50 per cent), whereas [U-14C]-glutamine decarboxylation was increased by LS (53 per cent) and MU (55 per cent) and decreased by MS (17 per cent). The results presented indicate that the reduction in lymphocyte proliferation due to LS, LU and PU could well be a consequence of changes in glucose and glutamine metabolism.

Use of adenosine in patients hospitalized in a university medical center

PURPOSE

Adenosine is a useful agent for the diagnosis and termination of tachycardias. The purpose of this study was to identify the rhythms for which adenosine is prescribed in hospitalized adults and to identify the reasons for its misuse.

PATIENTS AND METHODS

Data were collected from the medical records of 100 patients who received intravenous adenosine while hospitalized at a university medical center. The characteristics of the patients, rhythms treated with adenosine, and dosages of adenosine were analyzed. In addition, internal medicine house officers were administered a questionnaire referring to an electrocardiogram of atrial fibrillation with a rapid ventricular response.

RESULTS

The arrhythmias for which adenosine was administered consisted of regular, narrow-QRS complex tachycardias in 33% of patients; atrial fibrillation in 32% of patients; regular, wide-QRS complex tachycardias in 23% of patients; atrial flutter in 10% of patients, and multifocal atrial tachycardia in 2% of patients. The mean (+/-SD) number of doses of adenosine given to each patient was 1.6+/-0.8, and the mean dose of adenosine was 7.8+/-2.8 mg. Internal medicine house officers prescribed 70% of the doses of adenosine and were as likely to use it for patients with atrial fibrillation as were surgical house officers. There was a 2% incidence of proarrhythmia, including asystole and polymorphic ventricular tachycardia. Thirty-one percent of the 100 house officers in our survey misdiagnosed a 12-lead electrocardiogram of rapid atrial fibrillation as paroxysmal supraventricular tachycardia, suggesting that adenosine may have been misused for atrial fibrillation because of errors in rhythm diagnosis. Only 5% of those who correctly diagnosed atrial fibrillation also answered that adenosine would be likely to terminate the arrhythmia, suggesting that a misunderstanding that adenosine terminates atrial fibrillation is not a common reason for its misuse.

CONCLUSIONS

Approximately 40% of hospitalized adults who are treated with adenosine receive the medication unnecessarily for atrial fibrillation or atrial flutter, and this misuse results in unnecessary expenses and risks of adverse effects. The primary reason that adenosine is misused for atrial fibrillation is the inability to recognize that rhythm on an electrocardiogram. House officers need additional education on the electrocardiographic recognition of atrial fibrillation.

[Health promotion and education: a diagnosis of sanitation conditions using participatory research and community education (São João dos Queiróz - Quixadá/Ceará, Brazil)]

This study was conducted in a rural community, São João dos Queiróz, a township in the county of Quixadá, Ceará, Brazil, using a combination of participatory research and community education in compliance with the health promotion reference and principles of the 1986 Ottawa Charter. The project was joined by representatives of several local government institutions and organizations from the grassroots community movement. The theme generating the research, as defined by an assembly meeting of the community association, was a diagnosis of sanitation conditions in the community. The starting point was the assessment of local conditions. Results showed adverse local conditions in sanitation, literacy, income, and employment. Suggestions for solving the problems were organized so as to be included in the planning agenda for local health policies. Evaluation was procedural and enriched with daily research activities. The problem-solving pedagogical approach developed during the educational process contributed to a critical reconstruction, appropriation, and sharing of the resulting knowledge.

Fish oil given by gavage increases lymphocyte proliferation and production of hydrogen peroxide by rat macrophages

1. The effect of fish oil (FO) administration by gavage (0.4% body weight) on macrophage and lymphocyte function was investigated in young male rats. The results were compared with those obtained by administration of soybean oil (SB) and cocoa butter (CB). 2. Lymphocyte proliferation was markedly increased by FO administration compared with control and other oils. 3. Macrophage phagocytosis capacity was not affected by FO, but it was increased by CB and SB. 4. The oils did not affect the production of O2.- but increased the production of H2O2 in the presence of PMA. 5. The administration of the oils did not markedly affect the activity of antioxidant enzymes in macrophages, except for a decrease in superoxide dismutase activity by FO.

Cardiac electrophysiologic effects of norepinephrine in human beings

BACKGROUND

The electrophysiologic effects of norepinephrine (NE) in human beings have not been previously described.

METHODS

The electrophysiologic effects of NE infused at a rate of 25 ng/kg/min were determined in 21 patients with a mean age of 41 +/- 11 years and without structural heart disease who underwent an electrophysiology procedure. In a subgroup of 10 patients electrophysiologic parameters were measured at baseline, after the infusion of NE, and after administration of beta-blockade while in continuous NE infusion.

RESULTS

The baseline NE plasma concentration of 298 +/- 153 pg/ml increased to 708 +/- 419 pg/ml after the infusion of NE. NE significantly increased the mean blood pressure, sinus cycle length, corrected sinus node recovery time, ventriculoatrial block cycle length, and the atrial and ventricular effective refractory periods. In a subset of 10 patients 0.2 mg/kg propranolol administered during continued infusion of NE resulted in a further increase in sinus cycle length, atrial-His interval, and ventricular refractoriness.

CONCLUSION

A physiologic elevation in the plasma NE concentration results in a depression of sinus node function and atrioventricular conduction and in prolongation of atrial and ventricular refractoriness. Some of NE's effects are partially offset by beta-adrenergic stimulation.

Changes in cardiac repolarization following short periods of ventricular pacing

INTRODUCTION

"Cardiac memory" (primary T wave change) is thought to occur after 15 minutes to several hours of right ventricular (RV) pacing. The two components of the temporal change in repolarization are memory and accumulation. The purpose of this study was to examine quantitatively the effect of short periods of ventricular pacing on the human cardiac action potential, using monophasic action potential (MAP) recordings.

METHODS AND RESULTS

Thirty-one patients (ages 43+/-14 years) with structurally normal hearts undergoing a clinically indicated electrophysiologic procedure were enrolled. Catheters were placed in the right atrium (RA) and RV, and a MAP catheter was positioned at the RV septum. APD90 was calculated from digitized MAP recordings. MAP morphology comparisons were performed using the root mean square (RMS) of the difference between complexes. All pacing was at 500-msec cycle length. There were four pacing protocols: (1) RA pacing was performed for approximately 15 minutes to evaluate temporal stability of the MAP recordings (5 pts); (2) to evaluate the memory phenomenon, four successive 1-minute episodes of RV pacing were interspersed with 2 minutes of RA pacing (5 pts); (3) the accumulation phenomenon was evaluated by assessing the effects of 1, 5, 10, and 15 minutes of RV pacing on the MAP during RA pacing (16 pts); and (4) 20 minutes of RV pacing was followed by 10 minutes of RA pacing to correlate visually apparent T wave changes with changes in MAP recordings (5 pts). In the control patients, no changes in APD90 or RMS analysis were noted during 14.9+/-1.4 minutes of RA pacing. In the second protocol, RMS of the difference between the baseline MAP complexes and the signal average of the first 50 beats following each of four 1-minute RV pacing trains demonstrated progressively greater differences in morphology after successive episodes of RV pacing. In protocol 3, RMS analysis identified a progressively greater difference between the baseline MAP recording and the average of the first 50 beats after 1, 5, 10, and 15 minutes of RV pacing. In protocol 4, visually apparent changes in T waves occurred in parallel with the RMS of the difference between the baseline MAP recordings and the average of the first 50 beats after 20 minutes of RV pacing. Similar changes also were demonstrated by APD90 analysis.

CONCLUSION

This study is the first to demonstrate that episodes of abnormal ventricular activation as short as 1 minute in duration may exert lingering effects on the repolarization process once normal ventricular activation resumes.

A prospective evaluation of two defibrillation safety margin techniques in patients with low defibrillation energy requirements

INTRODUCTION

In patients undergoing defibrillator implantation, an appropriate defibrillation safety margin has been considered to be either 10 J or an energy equal to the defibrillation energy requirement. However, a previous clinical report suggested that a larger safety margin may be required in patients with a low defibrillation energy requirement. Therefore, the purpose of this prospective study was to compare the defibrillation efficacy of the two safety margin techniques in patients with a low defibrillation energy requirement.

METHODS AND RESULTS

Sixty patients who underwent implantation of a defibrillator and who had a low defibrillation energy requirement (< or = 6 J) underwent six separate inductions of ventricular fibrillation, at least 5 minutes apart. For each of the first three inductions of ventricular fibrillation, the first two shocks were equal to either the defibrillation energy requirement plus 10 J (14.6+/-1.0 J), or to twice the defibrillation energy requirement (9.9+/-2.3 J). The alternate technique was used for the subsequent three inductions of ventricular fibrillation. For each induction of ventricular fibrillation, the first shock success rate was 99.5%+/-4.3% for shocks using the defibrillation energy requirement plus 10 J, compared to 95.0%+/-17.2% for shocks at twice the defibrillation energy requirement (P = 0.02). The charge time (P < 0.0001) and the total duration of ventricular fibrillation (P < 0.0001) were each approximately 1 second longer with the defibrillation energy requirement plus 10 J technique.

CONCLUSION

This study is the first to compare prospectively the defibrillation efficacy of two defibrillation safety margins. In patients with a defibrillation energy requirement < or = 6 J, a higher rate of successful defibrillation is achieved with a safety margin of 10 J than with a safety margin equal to the defibrillation energy requirement.

Long-term follow-up after radiofrequency ablation of paroxysmal supraventricular tachycardia in patients with tachycardia-induced atrial fibrillation

Four of 12 patients (33%) with paroxysmal supraventricular tachycardia (PSVT) and tachycardia-induced atrial fibrillation (AF) had recurrences of paroxysmal AF after successful catheter ablation of the PSVT. This study demonstrates that AF often remains a problem after radiofrequency catheter ablation of PSVT in patients with tachycardia-induced AF, and it may not be possible to predict in which patients this will be the case.

Predictors of crossover to a left ventricular approach for atrioventricular junction ablation

In a retrospective analysis of patients referred for atrioventricular node radiofrequency ablation, male gender and a history of hypertension were found to be predictors of crossover to a left ventricular approach for success. This subgroup of patients may benefit from early crossover if initial attempts at right-sided ablation fail.

Cost comparison of radiofrequency modification and ablation of the atrioventricular junction in patients with chronic atrial fibrillation

BACKGROUND

Because it is not clear which technique is less expensive, the purpose of this study was to compare the cost of radiofrequency modification and ablation of the atrioventricular (AV) node in drug-refractory patients with atrial fibrillation and an uncontrolled ventricular rate.

METHODS AND RESULTS

The initial nominal charges for a successful procedure were compared in 10 patients with chronic atrial fibrillation who underwent modification of the AV node ($13 109+/-2002) and 14 similar patients who underwent ablation and pacemaker implantation ($28 302+/-2023, P<.001). On the basis of the long-term follow-up of patients who underwent each procedure, it was assumed that 31% of patients selected for the modification procedure would require a permanent pacemaker for inadvertent AV block or because of AV nodal ablation after a failed modification procedure and that the recurrence rate after AV node ablation would be 2%. The annual charges during follow-up were predicted and adjusted for recurrences and the need for additional procedures. The adjusted total charges at 1 year of follow-up were significantly lower for the modification procedure ($19 389+/-2002) than for the ablation procedure ($28 485+/-2023, P<.001). After 10 years of follow-up, the cumulative, adjusted charges for modification were $20 016 (42%) less than for ablation.

CONCLUSIONS

The initial charges generated by AV node modification are significantly lower than for AV node ablation in patients with chronic atrial fibrillation. Even when adjusted for higher failure and recurrence rates, the modification procedure retains a major cost advantage over ablation during long-term follow-up.