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The tomato–potato psyllid (TPP) Bactericera cockerelli, is a serious pest of solanaceous crops. Some populations are becoming pesticide-resistant, increasing the need for alternatives such as biological control (BC). This approach may be improved by combining different species of BC agents. We conducted three separate experiments to test four BC agents, either alone or combined with others: (1) A laboratory assay to test the effect of buckwheat (Fagopyrum esculentum) and alyssum (Lobularia maritima) flowers on the longevity of females of the parasitic wasp Tamarixia triozae; (2) A no-choice laboratory assay to investigate the consumption of B. cockerelli life stages by the predatory bug Engytatus nicotianae; (3) A cage experiment in a greenhouse to assess four natural enemy species against B. cockerelli on tomatoes: these were the predators Cleobora mellyi, Amblydromalus limonicus, E. nicotianae, and T. triozae. Access to buckwheat flowers allowed female T. triozae to live for an average of 10.9 days compared to 2.1 days with alyssum and 1.4 day with water but did not improve the BC of B. cockerelli. Adult E. nicotianae preyed on all offered B. cockerelli stages. In experiment 3, combinations of T. triozae with A. limonicus or E. nicotianae were not significantly better than single natural enemy species, except for the reduction of nymphal populations when A. limonicus and T. triozae were combined. Although there were few significant reductions in numbers of TPP when using natural enemy species combinations, some species showed good potential when used alone. We suggest testing earlier release of combinations of natural enemy for evaluate its impact on TPP.

The main contemporary challenge for agriculture is to meet the food demands of the increasing world population while becoming more environmentally sustainable. One way to achieve this is through the promotion of functional biodiversity and the ecosystem (nature’s) services (ES) that it can provide. The Syrphinae subfamily is a widespread group of hoverflies with a high potential for that service. Hence, the present review aims to synthesize the existing literature on this group. This review is divided in three main sections. First, we focus on those aspects of the ecology of hoverflies that are relevant to their role in biological control. These are divided into nutrition, feeding preferences and prey detection of the different developmental stages, overwintering and the effect of landscape on their dispersal and efficacy. Second, we review the ES that predatory hoverflies can provide, particularly pollination and biological control. Finally, we discuss those farming practices that can affect the effectiveness of these Diptera as providers of ES. Overall, this review highlights the potential, as well as limitations and current gaps in knowledge, for enhancing the efficacy of hoverflies as ecosystem-service providers in agricultural systems. info:eu-repo/semantics/acceptedVersion

The tomato/potato psyllid (TPP), Bactericera cockerelli (Hemiptera, Triozidae), is an adventive psyllid in New Zealand that is a major pest of solanaceous crops and a serious threat to growers in the glasshouse industry. Worldwide, evaluation of potential biological control (BC) agents is normally conducted using single species and this is the case with some potential BC agents for TPP. However, the idea that multiple species can act synergistically remains largely untested so that is the aim of the current work, which is funded by Tomatoes New Zealand. The introduced parasitoid Tamarixia triozae is a BC agent of TPP that attacks mainly late instars. It lives for just 1 day when provided with water but can live up to 11 days (and consume more pests) when nectar in the flowers of buckwheat (Fagopyrum esculentum) is provided. In addition, another potential BC agent, the mirid bug Engytatus nicotianae, prefers young nymphal instars, while the ladybird Cleobora mellyi is voracious and consumes all instars. We are testing combinations of these species to understand the potential for synergies between and within trophic levels for better biological control.

We propose and investigate a new resource allocation technique for the downlink of time-division multiple access (TDMA)-based fixed broadband wireless access systems (FBWA) with full frequency reuse. This technique, named power-shaped advanced resource assignment exploits an appropriate set of power profiles which limit (or shape) the power transmitted in each slot of the frame and are suitably reused among the cells, in order to efficiently distribute the intercell and intersector interference inside the frame and to make it partially predictable. In systems where base stations assign radio resources in an uncoordinated fashion, this allows the allocation algorithm to assign time slots to users on the basis of the power required to fulfill a predefined carrier-to-interference ratio, since worst case interference can be suitably estimated; moreover, different degrees of protection against interference are provided across the slots to efficiently accommodate users with different location-dependent channel conditions. Simulation results for a typical cellular FBWA system show that this technique significantly improves the capacity with respect to other techniques recently proposed, e.g., the enhanced staggered resource assignment, even when they use power control. Moreover, an analytical framework useful to understand the concept of power shaping and to discuss some guidelines for the design of power profiles is provided.

This study evaluated the dose-response effect of inhaled nitric oxide (NO) on gas exchange, haemodynamics, and respiratory mechanics in patients with adult respiratory distress syndrome (ARDS). Of 19 consecutive ARDS patients on mechanical ventilation, eight (42%) responded to a test of 10 parts per million (ppm) NO inhalation with a 25% increase in arterial oxygen tension (Pa,O2,) over the baseline value. The eight NO-responders were extensively studied during administration of seven inhaled NO doses: 0.5, 1, 5, 10, 20, 50 and 100 ppm. Pulmonary pressure and pulmonary vascular resistance exhibited a dose-dependent decrease at NO doses of 0.5-5 ppm, with a plateau at higher doses. At all doses, inhaled NO improved O2 exchange via a reduction in venous admixture. On average, the increase in Pa,O2, was maximal at 5 ppm NO. Some patients, however, exhibited maximal improvement in Pa,O2 at 100 ppm NO. In all patients, the increase in arterial O2 content was maximal at 5 ppm NO. The lack of further increase in arterial O2 content above 5 ppm partly depended on an NO-induced increase in methaemoglobin. Respiratory mechanics were not affected by NO inhalation. In conclusion, NO doses < or =5 ppm are effective for optimal treatment both of hypoxaemia and of pulmonary hypertension in adult respiratory distress syndrome. Although NO doses as high as 100 ppm may further increase arterial oxygen tension, this effect may not lead to an improvement in arterial O2 content, due to the NO-induced increase in methaemoglobin. It is important to consider the effect of NO not only on arterial oxygen tension, but also on arterial O2 content for correct management of inhaled nitric oxide therapy.

To understand the origin and past dissemination of human T-cell leukemia/lymphotropic virus type I (HTLV-I) in Latin America, we conducted a phylogenetic study of five new HTLV-I isolates from Argentina. We sequenced partial fragments of long terminal repeats (LTR) of the new HTLV-Is, and then the sequences were subjected to a phylogenetic analysis for comparison with other HTLV-Is of various geographical origins. Our results indicated that all the isolates were members of the Cosmopolitan group. Furthermore, most (four out of five isolates) of the new HTLV-Is belonged to the Transcontinental (A) subgroup, the most widespread subgroup of the four subgroups in the Cosmopolitan group. In this subgroup, they were closely related to HTLV-Is found in other South American countries including those of Amerindians, and were different from those found in Africa. In contrast, the remaining one HTLV-I (ARGMF) did not show any clear similarity to known HTLV-I isolates belonging to the Cosmopolitan group. The close similarity of South American HTLV-Is strongly suggests a common origin of the virus in this continent. Our results do not support the proposed idea of recent introduction of HTLV-I into South America as a consequence of the slave trade from Africa, where phylogenetically different HTLV-Is predominate. J. Med. Virol. 55:152–160, 1998. © 1998 Wiley-Liss, Inc.

To evaluate a least squares fitting technique for the purpose of measuring total respiratory compliance (Crs) and resistance (Rrs) in patients submitted to partial ventilatory support, without the need for esophageal pressure measurement.Prospective, randomized study.A general ICU of a University Hospital.11 patients in acute respiratory failure, intubated and assisted by pressure support ventilation (PSV).Patients were ventilated at 4 different levels of pressure support. At the end of the study, they were paralyzed for diagnostic reasons and submitted to volume controlled ventilation (CMV).A least squares fitting (LSF) method was applied to measure Crs and Rrs at different levels of pressure support as well as in CMV. Crs and Rrs calculated by the LSF method were compared to reference values which were obtained in PSV by measurement of esophageal pressure, and in CMV by the application of the constant flow, end-inspiratory occlusion method. Inspiratory activity was measured by P0.1. In CMV, Crs and Rrs measured by the LSF method are close to quasistatic compliance (-1.5 +/- 1.5 ml/cmH2O) and to the mean value of minimum and maximum end-inspiratory resistance (+0.9 +/- 2.5 cmH2O/(l/s)). Applied during PSV, the LSF method leads to gross underestimation of Rrs (-10.4 +/- 2.3 cmH2O/(l/s)) and overestimation of Crs (+35.2 +/- 33 ml/cmH2O) whenever the set pressure support level is low and the activity of the respiratory muscles is high (P0.1 was 4.6 +/- 3.1 cmH2O). However, satisfactory estimations of Crs and Rrs by the LSF method were obtained at increased pressure support levels, resulting in a mean error of -0.4 +/- 6 ml/cmH2O and -2.8 +/- 1.5 cmH2O/(l/s), respectively. This condition was coincident with a P0.1 of 1.6 +/- 0.7 cmH2O.The LSF method allows non-invasive evaluation of respiratory mechanics during PSV, provided that a near-relaxation condition is obtained by means of an adequately increased pressure support level. The measurement of P0.1 may be helpful for titrating the pressure support in order to obtain the condition of near-relaxation.

Following the outbreak of Chikungunya virus fever occurred in the summer 2007 in Emila Romagna (an administrative region located along the Adriatic (East) coast of Italy) a regional plan for Aedes albopicus control has been implemented. The major items of the plan are here reported and discussed.

In this paper we propose an efficient and simple method to improve system capacity in GSM/GPRS/EDGE radio systems. It exploits the power shaping concept and the parameter "TRX power reduction" already present in the standard and does not require major modifications to operators specific radio resource management algorithms. Power-shaping means assigning in advance (static allocation) a maximum power level to each channel before dynamically performing channel allocation. This is done by exploiting a set of suitably reused power profiles that partially organize the inter-cell interference in the available channels and make it partially predictable. This technique, thanks to the possibility of tightening the reuse factor, permits to increase the system capacity for both voice and data services if compared to most common reuse schemes or to the widely used concentric cells schemes. This is shown in the results where an interesting gain is achieved by power shaping with power reduction with respect to the other schemes.

Emulation capability in network simulation allows exposing experimental algorithms and protocols to live traffic load and to introduce real packet processing times. This paper describes the design and implementation of the emulation facility in the simple ad hoc simulator (SAM). The emulation architecture works in the user space allowing implementing and testing routing protocols for ad hoc networks. With respect to SAM, the emulator gives the possibility to test the routing protocols with a real exchange of signaling and data packets between the hosts present in the network. With respect to a wireless live test, the emulator works on hosts connected each other via wired links and the wireless channel is simulated

In ‘Beyond 3G’ wireless networking scenarios, characterized by the cooperation of multiple access networks comprising different radio access technologies, Multi-Radio Resource Management (MRRM) mec ...

In this paper we investigate energy efficiency and performance of a multi-hop communication in a wireless sensor network where energy efficient geographic forwarding algorithms are implemented. Starting from a reference case, based on a geographic information only, which optimizes the advancement toward the destination, we introduce here adaptive strategies that exploit channel and energy information and try to optimize the energy consumption or the energy-to-advancement ratio. We also propose an integrated MAC algorithm, which uses forwarding metrics to control the contention of the channel, and explore the possible benefits that can be gained by the use of coding which reduces the power requirements in the transmission of the data packets. The results show that the use of channel and energy information in the forwarding process improves the energy efficiency, but the gain achievable is heavily influenced by the fixed energy cost of MAC operations. However, the proposed MAC design keeps the energy cost limited and independent of the node density. It is also shown, that the use of coding does not reduce energy consumption when the required processing is energy consuing. The best energy behavior is achieved by the forwarding algorithm that minimizes the energy-to-advancement ratio which saves 20-40% of energy with respect to the reference case.

This paper addresses the issues of distributed dynamic resource allocation (DRA) in the downlink of a SDMA broadband wireless packet network with multiple access points and adaptive antennas. Packet access and downlink beamforming make the intercell interference hard to predict, and how to handle it in order to efficiently perform slot and power allocation is still an open issue. We propose here new DRA strategies for efficient allocation in a distributed environment, which jointly consider spatial compatibility of users and an intercell interference estimation based on a fraction of the worst case interference measurements. The latter is independent of the actual allocation. We consider a low mobility TDD system with synchronized base stations and we assume perfect channel knowledge. The algorithms which are introduced and compared are the distributed max-min fit (DMMF) and the distributed reverse fit (DRF), which are based on the max-min fit criterion, the DMMF combined with the novel concept of nulls preallocation, where each AP reserves some beamforming nulls for the most interfered users of neighboring cells, and the power shaping technique (PS-DRA for SDMA), which efficiently exploits static power preallocation on time slots. The numerical results show that our techniques are able to significantly reduce the gap between a greedy centralized strategy that fully coordinates all the access ports and the baseline case of random distributed allocation, previously proposed for packet access. However, distributed power control in a packet switched environment with downlink beamforming still remains a hard task: nevertheless, PS-DRA is an efficient solution for joint slot-power allocation

This paper investigates the performance of scheduling on a SDMA multicellular packet access systems. Scheduling with spatial division multiple access (SDMA) has been considered on the uplink of a single cell with an ad-hoc scheduling algorithm [Hujun Yin et al., 2002]. Here we consider the downlink of a multicell network and we first apply wireless fair queuing scheduling to SDMA, in the new multicellular environment. We consider the issues related to beamforming, intercell interference and fairness among users. We take into account heterogeneous traffic classes with different QoS requirements and we show that the proposed scheme is feasible in the new multicellular SDMA environment. It increases system capacity for delay sensitive users and achieve better per user QoS performance with respect to the known earliest due date (EDD) strategy and the baseline case of first-come first-served (FCFS), in the same environment.

In this paper we address the problem of multiuser scheduling with multi-radio access selection, i.e., the data flow of a given user can be scheduled over multiple radio access technologies of different operators. We show that performance gains are possible and come from multiuser diversity as well as multi-radio diversity, as both the best user and the best radio access can be selected, at any given time, to get to optimal performance. We compare a terminal-based strategy where users compete to choose the best radio access, and a network-based case where the network choose the users to serve at a given time. This work assesses the performance gain due to both multi radio access and multiuser diversity with respect to the no-multi-radio case, where users are constrained to connect to the same single radio access

With the aim of optimizing the performance of a data protocol, we investigate the effects and the role played by distributed resource allocation and rate/power adaptation in a wireless SDMA/TDMA network where multiple antenna elements are used at both transmitter and receiver side, and perfect channel state information (CSI) is available at the receiver only. We consider the uplink of a multiple cell system, throughput-driven allocation and adaptation algorithms, and address the issues related to the management of intercell interference. We find that the capacity of the network is heavily affected by the presence of interference and it is important to exploit a part of the receiving antennas to mitigate strong interference and to have an estimation of the interference covariance matrix to tune allocation and adaptation algorithms. The results show that the joint use of distributed best-fit allocation algorithms with adaptive antenna selection allow substantial improvement with respect to the basic case of random access. Moreover, simple stream control strategies prevent capacity degradation when the offered load exceeds the maximum capacity.

In this paper we propose energy efficient forwarding techniques in a fading environment which exploit channel knowledge by means of nodes cooperation. Unlike forwarding strategies based on geographic information only, channel knowledge allows to take advantage from diversity by means of selection of the best node to forward the packet, and also to achieve higher energy savings thanks to power control. We also consider the case of multi-route diversity where redundancy packets are sent over different paths. We propose several adaptive strategies which explicitly address the energy issues and we compare them in terms of total consumed energy, mean packet error probability and delay. As a reference case we consider a forwarding strategy based on pure geographic routing (without channel knowledge). The results show that a considerable improvement can be obtained with respect to the pure geographic forwarding. Our algorithms are also in the direction of a cross layer view, since routing decisions are taken adaptively through physical layer information

This paper addresses dynamic resource allocation (DRA) with power control for the downlink of a Spatial Divi- sion Multiple Access (SDMA) broadband multicellular wireless packet network with adaptive antennas. The main issue for dis- tributed DRA is how to manage the intercell interference, which is very difficult to handle in an uncoordinated environment, due to packet access and downlink beamforming. The issue of effi- ciently performing DRA and power control in such environment is still open. In this paper we propose to do the slot allocation distributedly with a rough estimate of the intercell interference, and the power control and beamforming in a centralized manner, after the allocation. This keep the computational effort low with respect to a completely centralized allocation algorithm. We show that the gap between a distributed algorithm with uncoordinated power control and a totally centralized allocation algorithm can be significantly reduced.

The Ambient Networks concept targets forthcoming dynamic communication environments, characterized by the presence of a multitude of different wireless devices, radio access technologies, network operators and business actors, which can form instant inter-network agreements with each other. MultiRadio Resource Management (MRRM) mechanisms, coordinating several radio accesses, fulfill a key role for providing wireless services with improved resource efficiency, coverage and service quality. This paper presents an MRRM concept for Ambient Networks, describes the principal MRRM functions and discusses design criteria. © 2005 IEEE.

We consider distributed dynamic slot and power allocation for the downlink of a TD/SDMA broadband wireless packet network with multiple access ports and adaptive antennas. The still open issue for packet multicell SDMA is how to manage the intercell interference, which is very difficult to predict in an uncoordinated environment, due to packet access and downlink beamforming. For this reason, doing distributed allocation efficiently as well as improving the performance by means of power control results in a very hard task. We propose a greedy SDMA algorithm exploiting the power shaping technique, which is based on a static preallocation of the transmit power to each slot of the frame. This permits to obtain a partial predictability of intercell interference, allowing different levels of estimated intercell interference and available power for each slot. We show that our greedy SDMA algorithm with power shaping increases system capacity with respect to the same algorithm without power shaping and reduces the performance gap with respect to a greedy centralized strategy, thus limiting the need of coordination among cells. Both centralized and distributed algorithms are compared, as reference, to the baseline case of random allocation, previously proposed for packet access.

This paper proposes a novel distributed dynamic resource allocation (DRA) algorithm for the downlink of a SDMA broadband wireless packet network with multiple access ports and adaptive antennas. With the new scheme, each access port (AP) independently preallocates some beamforming nulls toward the most interfered users of the neighbor APs and broadcasts this information to the other APs. Then all APs independently and distributedly perform the allocation of their users using the distributed max-min fit (DMMF) scheme. Simulation results show a significant improvement over the DMMF without nulls preallocation and a significantly reduced gap between the DMMF and the centralized max-min fit (CMMF) algorithm, which performs the allocation by fully coordinating all the access ports. As a baseline case, the performance of a random slot allocation algorithm is also reported.

We study here the performance of the data transmission protocol in a multicell SDMA/TDMA MIMO system running a distributed throughput-driven slot allocation algorithm, as a function of reuse distance, propagation exponent, and network load. Multiple antenna elements are used at both transmitter and receiver side, and perfect channel state information (CSI) is available at the receiver only. A simplified scenario with two access points is considered. We find that the capacity of the network is heavily affected by the presence of interference and we show that the joint use of an estimation of interference covariance matrix and adaptive stream-limited antenna selection prevents capacity degradation when the offered load increases. The results show that the adaptive stream-limited antenna selection introduces a considerable performance improvement over the traditional approach of frequency reuse.

We apply dynamic slot allocation with power-shaping to TDMA-based (pure or hybrid) mobile radio systems. We show that this technique, originally proposed by the Authors for fixed broadband wireless access systems, where interference is mitigated by the use of highly directional antennas, is able to increase the capacity even in full frequency reuse cellular systems with omnidirectional antennas. By using a set of power profiles, suitably defined here for hexagonal cells with three sectors, that limit (or shape) the power transmitted in each slot of the frame, this allocation technique partially organizes the intercell and intersector interference in the available slots and makes it partially predictable. This allows an efficient use of radio resources, when the base stations assign radio resources in an uncoordinated fashion without the need of centralized strategies requiring heavy signaling load.

In this paper we investigate a new dynamic resource allocation technique for TDMA and TD/CDMA cellular radio systems with full frequency reuse. Unlike traditional allocation strategies, that first allocate the time slots and then perform power control, the proposed technique first assigns in advance (static allocation) a maximum power level to each channel and then dynamically performs channel allocation and fine power control. This is done by exploiting a set of suitably reused power profiles that partially organize the intercell and intersector interference in the available slots and make it partially predictable. We show that this technique, originally proposed by the Authors for fixed broadband wireless access systems, where interference is mitigated by the use of highly directional antennas, is able to increase the capacity of systems with and without centralized or partially centralized resource management control. Moreover, it is also able to fill the efficiency gap between centralized and not centralized strategies. In our investigation a greedy algorithm for resource allocation suitable for both centralized and not centralized management is also proposed.

We introduce here a new class of packet scheduling techniques for TDMA-based (pure or hybrid) cellular packet radio networks with full frequency reuse. These algorithms, which are suited for networks with both centralized and distributed control, assign the available resources according to the SIR predicted at each slot of the frame. Partial prediction of the interference is made possible by the static pre-assignment in each cell of a maximum transmitted power level to each slot of the frame. This technique, also named power shaping, exploits a set of suitably reused power profiles to partially organize the intercell and intersector interference in the available slots. Unlike traditional channel state dependent scheduling techniques, which are not able to deal with quasi-stationary location-dependent radio channel conditions, the proposed method is able to provide channel resources with different levels of SIR inside the frame, even in stationary environments, and to assign them to the packets waiting for service. We show that these techniques are able to increase the capacity of systems with and without centralized resource management control, while maintaining the capability of providing acceptable quality of service to heterogeneous classes of users.

Single lung transplantation can be a suitable therapeutic option for a wide range of end-stage lung diseases: pulmonary fibrosis, emphysema, primary pulmonary hypertension and Eisenmenger's syndrome. Yet, patients suffering from different diseases have significantly different cardiovascular and respiratory functional profiles that can exert a profound influence on their response to the perioperative procedures. Our purpose is to analyze whether the patient's underlying disease can influence the early postoperative outcome after single lung transplantation.We carried out a retrospective analysis on perioperative charts of patients undergoing single lung transplantation during an 8-year period. We focused our attention on the following data: underlying lung disease, age, sex, baseline cardiorespiratory data (pulmonary artery pressure, cardiac index, forced expired volume, vital capacity, arterial blood gases, body mass index), intraoperative data (duration of graft ischemia, use of cardiopulmonary bypass) and indexes of adverse postoperative outcome (in-hospital death, mechanical ventilatory support7 days). Patients were gathered in 3 groups (restrictive, obstructive and vascular) according to the kind of disease and functional data and the association between disease and outcome was assessed by means of logistic regression analysis. Moreover, we evaluated whether any of the patient's functional parameters could be considered predictive of adverse postoperative outcome.We observed a weak association between restrictive disease and adverse postoperative outcome while, on the other hand, obstructive and vascular forms showed a close association with an adverse outcome, with a borderline statistical significance. Among all the considered variables, only intraoperative use of CPB turned out to be predictive of adverse outcome, while other variables simply indicated a trend towards a better outcome.Patients with vascular and obstructive diseases have the worst postoperative course, with a higher in-hospital mortality rate and longer duration of ventilation; in particular, the perioperative course of vascular patients is heavily influenced by the intraoperative use of cardiopulmonary bypass.

This paper investigates a new resource allocation technique for TDMA-based fixed broadband wireless access systems (FBWA) with full frequency reuse where base stations assign radio resources in an uncoordinated fashion. This technique, named power-shaped advanced resource assignment (PSARA) exploits an appropriate set of power profiles that limit (or shape) the power transmitted in each slot of the frame with the aim of helping the allocation algorithm to efficiently distribute the intercell and intersector interference inside the frame. Simulation results for a typical cellular FBWA system show that this technique significantly improves the capacity with respect to other techniques previously proposed, e.g. the enhanced staggered resource assignment (ESRA), even when they use power control. Moreover, an analytical framework useful to understand the concept of power-shaping and to discuss some guidelines for the design of power profiles is provided.

Analysis of haemodynamic problems during single-lung transplantation and of methodologies employed for their treatment.clinical retrospective study.General University Hospital.patients with irreversible lung disease, either parenchymal or vascular, undergoing single lung transplantation.recording of circulatory failure episodes and treatment with pharmacologic support or cardiopulmonary bypass. Modifications occurring during the study period with respect to drugs administered. Evaluation of the consequences of cardiopulmonary bypass on the postoperative outcome, namely on the duration of mechanical ventilation and length of stay in the intensive care unit.During the last 9 years 69 single-lung transplantations have been performed. In 50% of cases a pharmacologic support has been employed; the drug association dobutamine/nitroprusside has been gradually replaced by the association norepinephrine/nitric oxide for the treatment of right ventricular failure. Twenty patients required cardiopulmonary bypass and this caused a significant increase of the duration of mechanical ventilation and length of stay in the intensive care unit.Hemodynamic changes during lung transplantation are complex and often severe, leading to a clinical status of right ventricular failure, that sometime requires a mechanical circulatory support. The introduction of nitric oxide in clinical practice significantly contributed to the optimization of intraoperative cardiocirculatory profile of patients, leading to a reduction in the use of vasoactive drugs and cardiopulmonary bypass.

To better understand the origin of human T-cell leukemia virus type l (HTLV-l) in South America, we conducted a phylogenetic study on 27 new HTLV-ls in Brazil. These were obtained from Brazilians of various ethnic origins, such as Japanese immigrants, whites, blacks and mulattos. We amplified and sequenced proviral DNAs of a part of the long terminal repeats. Phylogenetic trees revealed that all but 6 of the new isolates were not only similar to each other but also similar to HTLV-ls of other South American countries, including those from Amerindians. However, the isolates differed from the HTLV-ls of Africa and Japan. The other six isolates were from Japanese immigrants and were phylogenetically almost identical to HTLV-ls in Japan but different from the majority of South American HTLV-ls, including the other new Brazilian HTLV-ls. These findings indicate that the recent introduction of HTLV-1 from Japan is limited to Japanese immigrants. In addition, the results do not support the prevailing hypothesis that HTLV-ls in South America were introduced by blacks who were brought from Africa as slaves. Rather, these results suggest that the majority of HTLV-1s prevailing in South America have spread from Amerindians, some of whom are likely to have possessed this human retrovirus from the beginning of their settlement in South America.

To review intra- and postoperative data regarding surgical reconstruction of the aortic arch performed at our cardiosurgical centre during the past four years, and thus to deepen understanding of neurologic morbidity and of what constitutes the most effective neuroprotection.Retrospective study.Regional University Hospital.29 patients who underwent reconstruction of aneurysm or dissection of the aortic arch. Intervention. Surgical replacement of the diseased aorta during deep hypothermia, alone or with selective cerebral perfusion (antegrade or retrograde).Overall mortality rate, neurologic morbidity rate, duration of extracorporeal circulation, of hypothermic circulatory arrest or of selective cerebral perfusion. Evaluation of the importance to neurological outcome of age, modality of operation (emergency or routine), biochemical parameters (glycemia, hematocrit) and perfusion technique. Recording of postoperative time of arousal, and possible correlation with length of selective cerebral perfusion.We observed a mortality rate of 39% (11 deaths) and a neurologic morbidity rate of 34%. Hypothermic circulatory arrest alone did not assure valid neuroprotection (5 cases, all with severe neurologic impairment), while better results were obtained with selective cerebral perfusion, especially antegrade (14 cases, with only 7% of neurologic morbidity rate). Hyperglycemia (250 mg%) proved to be significantly associated (p=0.002) with increased incidence of adverse neurologic outcome, and the same association was observed between emergency status and adverse neurologic outcome (p=0.002). Moreover, we found an unexpected linear correlation between time of selective cerebral perfusion and postoperative time of arousal (r=0.728, p=0.000).Deep hypothermic circulatory arrest with selective cerebral perfusion currently represent a valid therapeutic option for brain preservation during reconstruction of the aortic arch in adults. It is mandatory to carry out a tight control of perfusion parameters (flow, pressures and temperature gradients) and biochemical variables (avoidance of hyperglycemia and modified ultrafiltration for fluid balance).

To understand the origin and past dissemination of human T-cell leukemia/lymphotropic virus type I (HTLV-I) in Latin America, we conducted a phylogenetic study of five new HTLV-I isolates from Argentina. We sequenced partial fragments of long terminal repeats (LTR) of the new HTLV-Is, and then the sequences were subjected to a phylogenetic analysis for comparison with other HTLV-Is of various geographical origins. Our results indicated that all the isolates were members of the Cosmopolitan group. Furthermore, most (four out of five isolates) of the new HTLV-Is belonged to the Transcontinental (A) subgroup, the most widespread subgroup of the four subgroups in the Cosmopolitan group. In this subgroup, they were closely related to HTLV-Is found in other South American countries including those of Amerindians, and were different from those found in Africa. In contrast, the remaining one HTLV-I (ARGMF) did not show any clear similarity to known HTLV-I isolates belonging to the Cosmopolitan group. The close similarity of South American HTLV-Is strongly suggests a common origin of the virus in this continent. Our results do not support the proposed idea of recent introduction of HTLV-I into South America as a consequence of the slave trade from Africa, where phylogenetically different HTLV-Is predominate.

We have studied the vertical distribution of Culicidae in the "Ancona di Bellocchio" protected area (Regional Park of the Po Delta, Emilia-Romagna, Italy) by means of nonilluminated CDC traps baited with CO2. Traps were placed at heights of 1.5, 3, 4, and 5 m from the ground in open areas and at 1.5, 3, 4, 5, 6, and 7 m in wooded areas. We calculated the average flying height of the species caught, i.e., in order of decreasing flying height, Culex pipiens Linnaeus s.l., Culex modestus Ficalbi, Coquillettidia richiardii (Ficalbi), Aedes detritus (Haliday), Aedes caspius (Pallas). We also calculated the linear regression lines for both sites and found that 90% of Ae. caspius flew within a height of 1.64 m from the ground level, 95% within 2.68 m, and 99% at a height not exceeding 4 m; whereas 90% of Cx. pipiens moved within 3.45 m from the ground level, 95% within 4.02 m, and 99% within 4.76 m. The vertical distributions of Ae. caspius and Cx. pipiens did not vary significantly over the seasons and were not affected by the presence of trees or variations in temperature and wind velocity within the range of measurements obtained. The data obtained provide useful information for planning Ae. caspius control measures based on a mechanical barrier capable of preventing mosquitoes from moving toward residential settlements and tourist resorts bordering on the protected area as an alternative to aerial treatment with the larvicide Bacillus thuringiensis subsp. israelensis.

Foram estudadas as reações de hipersensibilidade tuberculínica induzidas por aplicações simultâneas, em adultos jovens, de tuberculina (PPD. RT-23, 2UT), com agulha e seringa e com o dermo-jet. Foram encontrados 61,3% de reatores nas aplicações com agulha e seringa para 40,0% de reatores nas aplicações com o dermo-jet. Os resultados não são considerados favoráveis ao uso do injetor a jato na prática corrente de aplicação do teste tuberculínico.

Body fluids and brain tissue from rabid human patients have demonstrated only low titers of interferon. Therefore, pharmacokinetic studies of systemically administered and locally injected leukocyte interferon were performed in 2 North American patients with suspected rabies who showed no clinically important side effects of this therapy. Similar therapy was given to 5 patients with symptomatic rabies in Europe and America. Although no prolongation of the clinical course was seen in 3 patients given high-dose intraventricular and systemic therapy, treatment was not initiated until between 8 and 14 days after symptoms were seen. The intraventricular dosage regimen produced cerebrospinal fluid levels that appeared to fall progressively over the 24 hours after injection and demonstrated good but somewhat delayed distribution into the lumbar sac. Titers produced by this therapy were 30- to 10,000-fold higher than those normally observed in this infection, however. In the patients treated at the highest dosage, a diminished and delayed antirabies neutralizing antibody titer was observed, probably a result of the administration of the exogenous interferon.

One of the most intriguing aspects concerning the pathogenesis of AIDS is the long period of latency of the HIV in human cells, not causing any cytopatic effect in some and, on the other hand, causing cell destruction, at short periods, in others. The various agents and the mechanisms they adopt to reactivate the latente HIV, were described. Also the frequent epidemiological observation on the presence of both such agents and the HIV in AIDS patients allowed the authors to speculate on the probable important role of a cohort of co-factors which determine the destiny of such individuals. Special considerations were made in respect to the hepatitis B virus, cytomegalovirus, herpesviruses (HHV-1, e and 6), EB virus, HTLV-1 and 2 retroviruses, group B arbovirus Maguary, malaria and other endemic infectious diseases which victimize millions of Brazilians. Accepting the importance of such co-factors acting on the viral gens that regulate the HIV expression in the host cell, it was speculated on the possible role of vaccines, such as the hepatitis B vaccine, and some antiviral drugs which could be useful in the indirect prevention of AIDS-disease in both HIV-carriers and those practising AIDS-high-risk-activities.