Data challenges for international health emergencies: lessons learned from ten international COVID-19 driver projects

The COVID-19 pandemic highlighted the importance of international data sharing and access to improve health outcomes for all. The International COVID-19 Data Alliance (ICODA) programme enabled 12 exemplar or driver projects to use existing health-related data to address major research questions relating to the pandemic, and developed data science approaches that helped each research team to overcome challenges, accelerate the data research cycle, and produce rapid insights and outputs. These approaches also sought to address inequity in data access and use, test approaches to ethical health data use, and make summary datasets and outputs accessible to a wider group of researchers. This Health Policy paper focuses on the challenges and lessons learned from ten of the ICODA driver projects, involving researchers from 19 countries and a range of health-related datasets. The ICODA programme reviewed the time taken for each project to complete stages of the health data research cycle and identified common challenges in areas such as data sharing agreements and data curation. Solutions included provision of standard data sharing templates, additional data curation expertise at an early stage, and a trusted research environment that facilitated data sharing across national boundaries and reduced risk. These approaches enabled the driver projects to rapidly produce research outputs, including publications, shared code, dashboards, and innovative resources, which can all be accessed and used by other research teams to address global health challenges.

Estimating the effective reproduction number for heterogeneous models using incidence data

The effective reproduction number, R ( t ) , plays a key role in the study of infectious diseases, indicating the current average number of new infections caused by an infected individual in an epidemic process. Estimation methods for the time evolution of R ( t ) , using incidence data, rely on the generation interval distribution, g(τ), which is usually obtained from empirical data or theoretical studies using simple epidemic models. However, for systems that present heterogeneity, either on the host population or in the expression of the disease, there is a lack of data and of a suitable general methodology to obtain g(τ). In this work, we use mathematical models to bridge this gap. We present a general methodology for obtaining explicit expressions of the reproduction numbers and the generation interval distributions, within and between model sub-compartments provided by an arbitrary compartmental model. Additionally, we present the appropriate expressions to evaluate those reproduction numbers using incidence data. To highlight the relevance of such methodology, we apply it to the spread of COVID-19 in municipalities of the state of Rio de Janeiro, Brazil. Using two meta-population models, we estimate the reproduction numbers and the contributions of each municipality in the generation of cases in all others.

Estimating the effective reproduction number for heterogeneous models using incidence data

The effective reproduction number, R ( t ) , plays a key role in the study of infectious diseases, indicating the current average number of new infections caused by an infected individual in an epidemic process. Estimation methods for the time evolution of R ( t ) , using incidence data, rely on the generation interval distribution, g(τ), which is usually obtained from empirical data or theoretical studies using simple epidemic models. However, for systems that present heterogeneity, either on the host population or in the expression of the disease, there is a lack of data and of a suitable general methodology to obtain g(τ). In this work, we use mathematical models to bridge this gap. We present a general methodology for obtaining explicit expressions of the reproduction numbers and the generation interval distributions, within and between model sub-compartments provided by an arbitrary compartmental model. Additionally, we present the appropriate expressions to evaluate those reproduction numbers using incidence data. To highlight the relevance of such methodology, we apply it to the spread of COVID-19 in municipalities of the state of Rio de Janeiro, Brazil. Using two meta-population models, we estimate the reproduction numbers and the contributions of each municipality in the generation of cases in all others.

Assessing the nationwide impact of COVID-19 mitigation policies on the transmission rate of SARS-CoV-2 in Brazil

COVID-19 is now identified in almost all countries in the world, with poorer regions being particularly more disadvantaged to efficiently mitigate the impacts of the pandemic. In the absence of efficient therapeutics or large-scale vaccination, control strategies are currently based on non-pharmaceutical interventions, comprising changes in population behavior and governmental interventions, among which the prohibition of mass gatherings, closure of non-essential establishments, quarantine and movement restrictions. In this work we analyzed the effects of 707 governmental interventions published up to May 22, 2020, and population adherence thereof, on the dynamics of COVID-19 cases across all 27 Brazilian states, with emphasis on state capitals and remaining inland cities. A generalized SEIR (Susceptible, Exposed, Infected and Removed) model with a time-varying transmission rate (TR), that considers transmission by asymptomatic individuals, is presented. We analyze the effect of both the extent of enforced measures across Brazilian states and population movement on the changes in the TR and effective reproduction number. The social mobility reduction index, a measure of population movement, together with the stringency index, adapted to incorporate the degree of restrictions imposed by governmental regulations, were used in conjunction to quantify and compare the effects of varying degrees of policy strictness across Brazilian states. Our results show that population adherence to social distance recommendations plays an important role for the effectiveness of interventions and represents a major challenge to the control of COVID-19 in low- and middle-income countries.

Assessing the nationwide impact of COVID-19 mitigation policies on the transmission rate of SARS-CoV-2 in Brazil

COVID-19 is now identified in almost all countries in the world, with poorer regions being particularly more disadvantaged to efficiently mitigate the impacts of the pandemic. In the absence of efficient therapeutics or large-scale vaccination, control strategies are currently based on non-pharmaceutical interventions, comprising changes in population behavior and governmental interventions, among which the prohibition of mass gatherings, closure of non-essential establishments, quarantine and movement restrictions. In this work we analyzed the effects of 707 governmental interventions published up to May 22, 2020, and population adherence thereof, on the dynamics of COVID-19 cases across all 27 Brazilian states, with emphasis on state capitals and remaining inland cities. A generalized SEIR (Susceptible, Exposed, Infected and Removed) model with a time-varying transmission rate (TR), that considers transmission by asymptomatic individuals, is presented. We analyze the effect of both the extent of enforced measures across Brazilian states and population movement on the changes in the TR and effective reproduction number. The social mobility reduction index, a measure of population movement, together with the stringency index, adapted to incorporate the degree of restrictions imposed by governmental regulations, were used in conjunction to quantify and compare the effects of varying degrees of policy strictness across Brazilian states. Our results show that population adherence to social distance recommendations plays an important role for the effectiveness of interventions and represents a major challenge to the control of COVID-19 in low- and middle-income countries.

Classification algorithm for congenital Zika Syndrome: characterizations, diagnosis and validation

Zika virus was responsible for the microcephaly epidemic in Brazil which began in October 2015 and brought great challenges to the scientific community and health professionals in terms of diagnosis and classification. Due to the difficulties in correctly identifying Zika cases, it is necessary to develop an automatic procedure to classify the probability of a CZS case from the clinical data. This work presents a machine learning algorithm capable of achieving this from structured and unstructured available data. The proposed algorithm reached 83% accuracy with textual information in medical records and image reports and 76% accuracy in classifying data without textual information. Therefore, the proposed algorithm has the potential to classify CZS cases in order to clarify the real effects of this epidemic, as well as to contribute to health surveillance in monitoring possible future epidemics.

Mathematical modeling of COVID-19 in 14.8 million individuals in Bahia, Brazil

COVID-19 is affecting healthcare resources worldwide, with lower and middle-income countries being particularly disadvantaged to mitigate the challenges imposed by the disease, including the availability of a sufficient number of infirmary/ICU hospital beds, ventilators, and medical supplies. Here, we use mathematical modelling to study the dynamics of COVID-19 in Bahia, a state in northeastern Brazil, considering the influences of asymptomatic/non-detected cases, hospitalizations, and mortality. The impacts of policies on the transmission rate were also examined. Our results underscore the difficulties in maintaining a fully operational health infrastructure amidst the pandemic. Lowering the transmission rate is paramount to this objective, but current local efforts, leading to a 36% decrease, remain insufficient to prevent systemic collapse at peak demand, which could be accomplished using periodic interventions. Non-detected cases contribute to a ∽55% increase in R0. Finally, we discuss our results in light of epidemiological data that became available after the initial analyses.

Case Fatality Rate Related to Microcephaly Congenital Zika Syndrome and Associated Factors: A Nationwide Retrospective Study in Brazil †

BACKGROUND

The clinical manifestations of microcephaly/congenital Zika syndrome (microcephaly/CZS) have harmful consequences on the child's health, increasing vulnerability to childhood morbidity and mortality. This study analyzes the case fatality rate and child-maternal characteristics of cases and deaths related to microcephaly/CZS in Brazil, 2015-2017.

METHODS

Population-based study developed by linkage of three information systems. We estimate frequencies of cases, deaths, case fatality rate related to microcephaly/CZS according to child and maternal characteristics and causes of death. Multivariate logistic regression models were applied.

RESULTS

The microcephaly/CZS case fatality rate was 10% (95% CI 9.2-10.7). Death related to microcephaly/CZS was associated to moderate (OR = 2.15; 95% CI 1.63-2.83), and very low birth weight (OR = 3.77; 95% CI 2.20-6.46); late preterm births (OR = 1.65; 95% CI 1.21-2.23), Apgar < 7 at 1st (OR = 5.98; 95% CI 4.46-8.02) and 5th minutes (OR = 4.13; 95% CI 2.78-6.13), among others.

CONCLUSIONS

A high microcephaly/CZS case fatality rate and important factors associated with deaths related to this syndrome were observed. These results can alert health teams to these problems and increase awareness about the factors that may be associated with worse outcomes.

Breast cancer mortality rates trends by race in São Paulo, Brazil

Background

Breast cancer is the main cause of female death by neoplasia in Brazil. Although half of the Brazilian population is black/brown (BB), socio-economic disparities translate in a vulnerable situation to those women. Access to health care is an important barrier to improve the health of BB women. This study aims to investigate trends in breast cancer mortality rates regarding race and age.

Methods

This is a population-based study of trends evaluation on breast cancer mortality in São Paulo state, Brazil, from 2000 to 2017. The absolute number of deaths and population figures (including race) by age-groups and years were available online from government data. Data on race were not available by ten-year age-groups, so the figures were projected according to the female age structure by year. Total rates by year and race were age-adjusted to the 'World Population (2000)'. For trend analysis, linear regression was used, with 5% level of significance.

Results

In the period were observed 60,940 breast cancer deaths, 76.7% in white and 17.5% in BB women. The absolute number of deaths in white and BB women was respectively 2,095 and 333 in 2000, and 3,076 and 999 in 2017. The total age-adjusted mortality rates per 100,000 women of white and BB in 2000 were respectively 16.4, 17.2 and 7.5. In 2017 rates were 14.6, 16.6 and 16.1. There was a trend towards reducing the mortality rates of white women (P = 0.002) and in their age-groups from 40 to 79 years (P &lt; 0.03). There was a trend towards increasing the mortality rates of BB women (P &lt; 0.001) and in all their age-groups (P &lt; 0.02).

Conclusions

Although breast cancer figures of death and mortality rates in BB women have more than doubled in 18 years, rates reached almost the same figures of white women in the period. Changes in behaviour risk factors may explain this result. However, it is very likely that access to health care to these women has been improved, reducing the disparities in the health system.

Key messages

Breast cancer mortality rates in black/brown women have reached almost the same figures as white women from 2000 to 2017 in São Paulo, Brazil. Access to health care in black women may have improved in São Paulo, Brazil.

COVID-19 in Northeast Brazil: achievements and limitations in the responses of the state governments

The COVID-19 pandemic has been most severe in the poorest regions of Brazil, such as the states of the Northeast Region. The lack of national policies for pandemic control forced state and municipal authorities to implement public health measures. The aim of this study is to show the effect of these measures on the epidemic. The highest incidence of COVID-19 among the nine states in the Northeast was recorded in Sergipe, Paraíba and Ceará. Piauí, Paraíba and Ceará were the states that most tested. Factors associated with transmission included the high proportion of people in informal work. States with international airports played an important role in the entry of the virus and the initial spread, especially Ceará. All states applied social distancing measures, banned public events and closed schools. The response was a significant increase in social distancing, especially in Ceará and Pernambuco, a decline in the reproduction rate (Rt), and a separation of the curve of observed cases versus expected cases if the non-pharmacological interventions had not been implemented in all states. Poverty, inequality, and the high rates of informal work provide clues to the intensity of COVID-19 in the region. On the other hand, the measures taken early by the governments mitigated the effects of the pandemic.

Interdependence between confirmed and discarded cases of dengue, chikungunya and Zika viruses in Brazil: A multivariate time-series analysis

The co-circulation of different arboviruses in the same time and space poses a significant threat to public health given their rapid geographic dispersion and serious health, social, and economic impact. Therefore, it is crucial to have high quality of case registration to estimate the real impact of each arboviruses in the population. In this work, a Vector Autoregressive (VAR) model was developed to investigate the interrelationships between discarded and confirmed cases of dengue, chikungunya, and Zika in Brazil. We used data from the Brazilian National Notifiable Diseases Information System (SINAN) from 2010 to 2017. There were three peaks in the series of dengue notification in this period occurring in 2013, 2015 and in 2016. The series of reported cases of both Zika and chikungunya reached their peak in late 2015 and early 2016. The VAR model shows that the Zika series have a significant impact on the dengue series and vice versa, suggesting that several discarded and confirmed cases of dengue could actually have been cases of Zika. The model also suggests that the series of confirmed and discarded chikungunya cases are almost independent of the cases of Zika, however, affecting the series of dengue. In conclusion, co-circulation of arboviruses with similar symptoms could have lead to misdiagnosed diseases in the surveillance system. We argue that the routinely use of mathematical and statistical models in association with traditional symptom-surveillance could help to decrease such errors and to provide early indication of possible future outbreaks. These findings address the challenges regarding notification biases and shed new light on how to handle reported cases based only in clinical-epidemiological criteria when multiples arboviruses co-circulate in the same population.

Impact evaluation of Zika epidemic on congenital anomalies registration in Brazil: An interrupted time series analysis

This study aimed to assess the impact of the Zika epidemic on the registration of birth defects in Brazil. We used an interrupted time series analysis design to identify changes in the trends in the registration of congenital anomalies. We obtained monthly data from Brazilian Live Birth Information System and used two outcome definitions: 1) rate of congenital malformation of the brain and eye (likely to be affected by Zika and its complications) 2) rate of congenital malformation not related to the brain or eye unlikely to be causally affected by Zika. The period between maternal infection with Zika and diagnosis of congenital abnormality attributable to the infection is around six months. We therefore used September 2015 as the interruption point in the time series, six months following March 2015 when cases of Zika started to increase. For the purposes of this analysis, we considered the period from January 2010 to September 2015 to be "pre-Zika event," and the period from just after September 2015 to December 2017 to be "post-Zika event." We found that immediately after the interruption point, there was a great increase in the notification rate of congenital anomalies of 14.9/10,000 live births in the brain and eye group and of 5.2/10,000 live births in the group not related with brain or eye malformations. This increase in reporting was in all regions of the country (except in the South) and especially in the Northeast. In the period "post-Zika event", unlike the brain and eye group which showed a monthly decrease, the group without brain or eye malformations showed a slow but significant increase (relative to the pre-Zika trend) of 0.2/10,000 live births. These findings suggest an overall improvement in the registration of birth malformations, including malformations that were not attributed to Zika, during and after the Zika epidemic.

Introducing risk inequality metrics in tuberculosis policy development

Global stakeholders including the World Health Organization rely on predictive models for developing strategies and setting targets for tuberculosis care and control programs. Failure to account for variation in individual risk leads to substantial biases that impair data interpretation and policy decisions. Anticipated impediments to estimating heterogeneity for each parameter are discouraging despite considerable technical progress in recent years. Here we identify acquisition of infection as the single process where heterogeneity most fundamentally impacts model outputs, due to selection imposed by dynamic forces of infection. We introduce concrete metrics of risk inequality, demonstrate their utility in mathematical models, and pack the information into a risk inequality coefficient (RIC) which can be calculated and reported by national tuberculosis programs for use in policy development and modeling.

Failure to account for heterogeneity in TB risk can mislead model-based evaluation of proposed interventions. Here, the authors introduce a metric to estimate the distribution of risk in populations from routinely collected data and find that variation in infection acquisition is the most impactful.

The nucleus reuniens: a key node in the neurocircuitry of stress and depression

The hippocampus and prefrontal cortex (PFC) are connected in a reciprocal manner: whereas the hippocampus projects directly to the PFC, a polysynaptic pathway that passes through the nucleus reuniens (RE) of the thalamus relays inputs from the PFC to the hippocampus. The present study demonstrates that lesioning and/or inactivation of the RE reduces coherence in the PFC-hippocampal pathway, provokes an antidepressant-like behavioral response in the forced swim test and prevents, but does not ameliorate, anhedonia in the chronic mild stress (CMS) model of depression. Additionally, RE lesioning before CMS abrogates the well-known neuromorphological and endocrine correlates of CMS. In summary, this work highlights the importance of the reciprocal connectivity between the hippocampus and PFC in the establishment of stress-induced brain pathology and suggests a role for the RE in promoting resilience to depressive illness.

Adenosine A2A receptor regulation of microglia morphological remodeling-gender bias in physiology and in a model of chronic anxiety

Developmental risk factors, such as the exposure to stress or high levels of glucocorticoids (GCs), may contribute to the pathogenesis of anxiety disorders. The immunomodulatory role of GCs and the immunological fingerprint found in animals prenatally exposed to GCs point towards an interplay between the immune and the nervous systems in the etiology of these disorders. Microglia are immune cells of the brain, responsive to GCs and morphologically altered in stress-related disorders. These cells are regulated by adenosine A_2A receptors, which are also involved in the pathophysiology of anxiety. We now compare animal behavior and microglia morphology in males and females prenatally exposed to the GC dexamethasone. We report that prenatal exposure to dexamethasone is associated with a gender-specific remodeling of microglial cell processes in the prefrontal cortex: males show a hyper-ramification and increased length whereas females exhibit a decrease in the number and in the length of microglia processes. Microglial cells re-organization responded in a gender-specific manner to the chronic treatment with a selective adenosine A_2A receptor antagonist, which was able to ameliorate microglial processes alterations and anxiety behavior in males, but not in females.

Hexagonal projected symmetries

In the study of pattern formation in symmetric physical systems, a three-dimensional structure in thin domains is often modelled as a two-dimensional one. This paper is concerned with functions in {\bb R}^{3} that are invariant under the action of a crystallographic group and the symmetries of their projections into a function defined on a plane. A list is obtained of the crystallographic groups for which the projected functions have a hexagonal lattice of periods. The proof is constructive and the result may be used in the study of observed patterns in thin domains, whose symmetries are not expected in two-dimensional models, like the black-eye pattern.

Astrocyte pathology in the prefrontal cortex impairs the cognitive function of rats

Interest in astroglial cells is rising due to recent findings supporting dynamic neuron-astrocyte interactions. There is increasing evidence of astrocytic dysfunction in several brain disorders such as depression, schizophrenia or bipolar disorder; importantly these pathologies are characterized by the involvement of the prefrontal cortex and by significant cognitive impairments. Here, to model astrocyte pathology, we injected animals with the astrocyte specific toxin L-α-aminoadipate (L-AA) in the medial prefrontal cortex (mPFC); a behavioral and structural characterization two and six days after the injection was performed. Behavioral data shows that the astrocyte pathology in the mPFC affects the attentional set-shifting, the working memory and the reversal learning functions. Histological analysis of brain sections of the L-AA-injected animals revealed a pronounced loss of astrocytes in the targeted region. Interestingly, analysis of neurons in the lesion sites showed a progressive neuronal loss that was accompanied with dendritic atrophy in the surviving neurons. These results suggest that the L-AA-induced astrocytic loss in the mPFC triggers subsequent neuronal damage leading to cognitive impairment in tasks depending on the integrity of this brain region. These findings are of relevance to better understand the pathophysiological mechanisms underlying disorders that involve astrocytic loss/dysfunction in the PFC.

Maternal serum progesterone, estradiol and estriol levels in successful dinoprostone-induced labor

Hormone-mediated quiescence involves the maintenance of a decreased inflammatory responsiveness. However, no study has investigated whether labor induction with prostanoids is associated with changes in the levels of maternal serum hormones. The objective of this study was to determine whether labor induction with dinoprostone is associated with changes in maternal serum progesterone, estradiol, and estriol levels. Blood samples were obtained from 81 pregnant women at term. Sixteen patients had vaginal birth after spontaneous labor, 12 required cesarean section after spontaneous labor and 16 underwent elective cesarean. Thirty-seven patients had labor induction with dinoprostone. Eligible patients received a vaginal insert of dinoprostone (10 mg) and were followed until delivery. Serum progesterone (P4), estradiol (E2) and estriol (E3) levels and changes in P4/E2, P4/E3 and E3/E2 ratios were monitored from admission to immediately before birth, and the association of these measures with the resulting clinical classification outcome (route of delivery and induction responsiveness) was assessed. Progesterone levels decreased from admission to birth in patients who underwent successful labor induction with dinoprostone [vaginal and cesarean birth after induced labor: 23% (P < 0.001) and 18% (P < 0.025) decrease, respectively], but not in those whose induction failed (6.4% decrease, P > 0.05). Estriol and estradiol levels, P4/E2, P4/E3 and E3/E2 ratios did not differ between groups. Successful dinoprostone-induced labor was associated with reduced maternal progesterone levels from induction to birth. While a causal relationship between progesterone decrease and effective dinoprostone-induced labor cannot be established, it is tempting to propose that dinoprostone may contribute to progesterone withdrawal and favor labor induction in humans.

Cardiopulmonary exercise testing variables as predictors of long-term outcome in thoracic sarcoidosis

Cardiopulmonary exercise testing (CPET) plays an important role in the assessment of functional capacity in patients with interstitial lung disease. The aim of this study was to identify CPET measures that might be helpful in predicting the vital capacity and diffusion capacity outcomes of patients with thoracic sarcoidosis. A longitudinal study was conducted on 42 nonsmoking patients with thoracic sarcoidosis (median age = 46.5 years, 22 females). At the first evaluation, spirometry, the measurement of single-breath carbon monoxide diffusing capacity (D_LCOsb) and CPET were performed. Five years later, the patients underwent a second evaluation consisting of spirometry and D_LCOsb measurement. After 5 years, forced vital capacity (FVC)% and D_LCOsb% had decreased significantly [95.5 (82-105) vs 87.5 (58-103) and 93.5 (79-103) vs 84.5 (44-102), respectively; P < 0.0001 for both]. In CPET, the peak oxygen uptake, maximum respiratory rate, breathing reserve, alveolar-arterial oxygen pressure gradient at peak exercise (P(A-a)O₂), and Δ SpO₂ values showed a strong correlation with the relative differences for FVC% and D_LCOsb% (P < 0.0001 for all). P(A-a)O₂ ≥22 mmHg and breathing reserve ≤40% were identified as significant independent variables for the decline in pulmonary function. Patients with thoracic sarcoidosis showed a significant reduction in FVC% and D_LCOsb% after 5 years of follow-up. These data show that the outcome measures of CPET are predictors of the decline of pulmonary function.

Electrophysiological classification of P2X7 receptors in rat cultured neocortical astroglia

BACKGROUND AND PURPOSE

P2X7 receptors are ATP-gated cation channels mediating important functions in microglial cells, such as the release of cytokines and phagocytosis. Electrophysiological evidence that these receptors also occur in CNS astroglia is rare and rather incomplete.

EXPERIMENTAL APPROACH

We used whole-cell patch-clamp recordings to search for P2X7 receptors in astroglial-neuronal co-cultures prepared from the cerebral cortex of rats.

KEY RESULTS

All the astroglial cells investigated responded to ATP with membrane currents, reversing around 0 mV. These currents could be also detected in isolated outside-out patch vesicles. The results of the experiments with the P2X [alpha,beta-methylene ATP and 2'-3'-O-(4-benzoyl) ATP] and P2Y receptor agonists [adenosine 5'-O-(2-thiodiphosphate), uridine 5'-diphosphate, uridine 5'-triphosphate (UTP) and UDP-glucose] suggested the involvement of P2X receptors in this response. The potentiation of ATP responses in a low divalent cation or alkaline bath, but not by ivermectin, made it likely that a P2X7 receptor is operational. Blockade of the ATP effect by the P2X7 antagonists Brilliant Blue G, calmidazolium and oxidized ATP corroborated this assumption.

CONCLUSIONS AND IMPLICATIONS

Rat cultured cortical astroglia possesses functional P2X7 receptors. It is suggested that astrocytic P2X7 receptors respond to high local ATP concentrations during neuronal injury.

[Coronary surgery after 70 years of age]

Previous reports on coronary artery bypass grafting in elderly patients have not usually addressed the current era of aggressive percutaneous angioplasty. To investigate this important subgroup of patients, we analyzed our recent coronary artery bypass grafting experience with patients 70 years of age or older from May 1988 to August 1993, 158 consecutive patients in this age range (mean age 70.3 years) underwent surgical revascularization at our institution. Overall operative mortality was 4.4% (7/158), with 71.4% (5/7) of deaths due to cardiac causes. Postoperative morbidity occurred in 50.6% (80/158) of patients but was of a serious nature in only 12.0% (19/158). Surgical priority was significantly correlated with operative mortality: 1.6% (2/122) for elective cases and 17.2% (5/29) for urgent or emergency cases (p < 0.01). Univariate analysis isolated the need for postoperative inotropic support or mechanical assistance, perioperative myocardial infarction and reoperation for bleeding as significant risk factors for operative mortality (p < 0.01). Of the patients discharged from the hospital, 144 (95.4%) were followed up for a mean of 23 months (3-62). During the follow-up period there were 3 deaths, all from non cardiac causes, and 92.3% of the patients were in Canadian Cardiovascular Society class I (CCS). These results indicate that, although with somewhat higher morbidity and mortality rates, elderly patients have a very acceptable operative risk in the current era of high-risk coronary artery bypass grafting, particularly if elective revascularization is possible.

The effect of drugs on the labeling of blood elements with technetium-99m

The influence of drugs on the labeling of red blood cells and plasma proteins with 99mTc has been reported. Any drug, which alters the labeling of the tracer, could be expected to modify the disposition of the radiopharmaceuticals. Red blood cells (RBC) labeled with technetium-99m (99mTc) are used for several evaluations in nuclear medicine. We have evaluated the effect of Thuya occidentalis, Peumus boldus and Nicotiana tabacum (tobacco) extracts on the labeling of RBC and plasma and cellular proteins with 99mTc. Blood was incubated with the drugs. Stannous chloride (SnCl2) solutions and 99mTc were added. Plasma (P) and blood cells (BC) were separated. The percentage of radioactivity (%ATI) bound to P and BC was determined. The %ATI on the plasma and cellular proteins was also evaluated by precipitation of P and BC samples with trichloroacetic acid (TCA) and isolation of soluble (SF) and insoluble (IF) fractions. The analysis of the results shows that there is a decrease in %ATI (from 97.64 to 75.89 percent) in BC with Thuya occidentalis extract. The labeling of RBC and plasma proteins can be decreased in presence of tobacco. This can be due either a direct or indirect effect (reactive oxygen species) of tobacco. The analysis of radioactivity in samples of P and BC isolated from samples of whole blood treated with Peumus boldus showed a rapid uptake of the radioactivity by blood cells in the presence of the Peumus boldus, whereas there was a slight decrease in the amount of 99mTc radioactivity in the TCA-insoluble fraction of plasma. This study shows that extracts of some medicinal plants can affect the radiolabeling of red blood cells with 99mTc using an in vitro technique.

Effect of Thuya occidentalis on the labeling of red blood cells and plasma proteins with technetium-99m

Thuya occidentalis is used in popular medicine in the treatment of condyloma and has antibacterial action. Red blood cells (RBC) labeled with technetium-99m (99mTc) are used for several evaluations in nuclear medicine. This labeling depends on a reducing agent, usually stannous ion. Any drug which alters the labeling of the tracer could be expected to modify the disposition of the radiopharmaceutical. We have evaluated the influence of T. occidentalis extract on the labeling of RBC and plasma proteins with 99mTc. Blood was withdrawn and incubated with T. occidentalis (0.25; 2.5; 20.5; and 34.1 percent v/v). Stannous chloride (1.2 micrograms/ml) was added and then 99mTc was added. Plasma (P) and blood cells (BC) were isolated, also precipitated with trichloroacetic acid and soluble (SF) and insoluble fractions (IF) separated. The analysis of the results shows that there is a decrease in radioactivity (from 97.64 to 75.89 percent) in BC with 34.1 percent of the drug. In the labeling process of RBC with 99mTc, the stannous and pertechnetate ions pass through the membrane, so we suggest that the T. occidentalis effect can be explained (i) by an inhibition of the transport of these ions, (ii) by damage in membrane, (iii) by competition with the cited ions for the same binding sites, or (iv) by possible generation of reactive oxygen species that could oxidize the stannous ion.

[Revascularization of the left coronary system with both internal mammary arteries in disease of the left main artery]

Although the longterm patency of the internal mammary artery (IMA) has been clearly demonstred, some doubts have been cast as to the perioperative adequacy of its flow. Hence, the sole use of these conduits in patients with left main disease (LMD) has been cautioned. To clarify the significance of this problem in our own population, we have considered in this study, 110 patients with significant LMD subjected to isolated myocardial revascularization from November 1992 trough November 1994. These patients were retrospectively divided into two Groups based on the type of revascularization of the left coronary territory: Group I-35 patients (mean age 51.8 +/- 6.0 years) in whom both the left anterior artery and branches of the circunflex artery were grafted with the left and right IMAs, respectively; and Group II-85 patients (mean age 63.9 +/- 7.7 years) in whom the anterior descending artery received the left IMA and the circunflex system received saphenous vein grafts. No patient in Group I received venous grafts in the left coronary system and in four patients of Group II the rigth IMA was anastomosed to the right coronary artery. The operative mortality was 0% in Group I and 3.5% in Group II (p = NS). The rate of perioperative myocardial infarction was 2.9% and 2.3%, respectively. The incidence of other complications was also similar in the two groups with regards to the need for inotropes (8.6% in the Group I and 7.0% in group II), and the prevalence of arrhythmias (22.8% and 23.5%) but was marginally higher in Group I with regards to reoperation for haemorrhage (8.6% and 3.5%) and sternal dehiscence (5.7% and 2.3%). The mean time of hospital admission was 8.3 days for both groups. The use of both IMAs as the sole conduits for revascularization of the left coronary system in patients with LMD did not increased surgical risk. Also, the hypothesis of insufficient blood flow to the myocardium does not appear to be supported by this study.

[Coronary surgery in patients 70 years and older]

Previous reports on coronary artery bypass grafting in elderly patients have not usually addressed the current era of aggressive percutaneous angioplasty. To investigate this important subgroup of patients, we analyzed our recent coronary artery bypass grafting experience with patients 70 years of age or older-From May 1988 to August 1993, 158 consecutive patients in this age range (mean age 73.0 years) underwent surgical revascularization at our institution. Overall operative mortality was 4.4% (7/158), with 71.4% (5/7) of deaths due to cardiac causes. Postoperative morbidity occurred in 50.6% (80/158) of patients but was of a serious nature in only 12.0% (19/158). Surgical priority was significantly correlated with operative mortality: 1.6% (2/122) for elective cases and 17.2% (5/29) for urgent or emergency cases (p < 0.01). Univariate analysis isolated the need for postoperative inotropic support or mechanical assistance, perioperative myocardial infarction and reoperation for bleeding as significant risk factors for operative mortality (p < 0.01). Of the patients discharged from the hospital, 144 (95.4%) were followed up for a mean of 23 months (3-62). During the follow-up period there were 3 deaths, all from non cardiac causes, and 92.3% of the patients were in Canadian Cardiovascular Society class I (CCS). These results indicate that, although with somewhat higher morbidity and mortality rates, elderly patients have a very acceptable operative risk in the current era of high-risk coronary artery bypass grafting, particularly if elective revascularization is possible.

Double-blind comparison of levocabastine eye drops with sodium cromoglycate and placebo in the treatment of seasonal allergic conjunctivitis

The efficacy and tolerance of topical administration (one drop in each eye q.i.d.) of levocabastine (0.5 mg/ml) was compared with that of sodium cromoglycate (20 mg/ml) and placebo in a 4-week double-blind trial in patients with seasonal allergic conjunctivitis. The investigator rated the treatment as globally good or excellent in significantly more patients treated with levocabastine (89%) than with cromoglycate (67%, P = 0.03) or placebo (48%, P = 0.007). The patients felt that the treatment was more efficacious in 95% (levocabastine), 35% (cromoglycate) and 36% (placebo) of the cases in which they had taken previous antiallergic medication. Total symptom severity according to the patients' diary data was consistently lower with levocabastine than with cromoglycate or placebo for all ocular symptoms. The difference was mainly apparent at the beginning of treatment. The percentage of symptom-free days was higher in the levocabastine group (53%) than in the cromoglycate (31%, P = 0.02) and the placebo group (34%, P = 0.08). Particularly at high-pollen days, levocabastine was superior to cromoglycate in eliminating moderate or severe symptoms. Adverse effects did not occur more frequently with levocabastine or cromoglycate than with placebo. It is concluded that levocabastine is an efficacious, fast-acting and well-tolerated drug in the management of seasonal allergic conjunctivitis.

T and B lymphocytes, total serum IgE and peripheral eosinophils in bronchial asthma

Absolute T and B lymphocytes, assayed by E and EAC rosette techniques, serum IgE levels, total eosinophil counts and delayed hypersensitivity cutaneous reactions were studied in 39 asthmatic subjects (19 extrinsic asthmas and 20 intrinsic asthmas) and in 15 age-matched control subjects. The mean value of T lymphocytes was 1753 +/- 709 mm.3 in the extrinsic group, 1511 +/- +/- 530 mm.3 in the intrinsic, and 1609 +/- 451 mm.3 in the controls. There was no statistical difference between the two groups of patients and the controls (P > 0.05). There was also no statistical difference of B lymphocytes between the two groups of patients and the controls. Serum IgE was elevated in 8 extrinsic asthmatics (42.1%), in one intrinsic (5%), and in none of the control population. The mean value of eosinophils ws significantly higher (P < 0.01) in the extrinsic group as compared to the controls. The same was true of the intrinsic group, but not so significantly (P congruent to 0.02). No correlation was observed between the number of T lymphocytes and the skin tests, serum IgE and total eosinophil counts.