An emission processing system for air quality modelling in the Mexico City metropolitan area: Evaluation and comparison of the MOBILE6.2-Mexico and MOVES-Mexico traffic emissions

This article describes the High-Elective Resolution Modelling Emission System for Mexico (HERMES-Mex) model, an emission processing tool developed to transform the official Mexico City Metropolitan Area (MCMA) emission inventory into hourly, gridded (up to 1km²) and speciated emissions used to drive mesoscale air quality simulations with the Community Multi-scale Air Quality (CMAQ) model. The methods and ancillary information used for the spatial and temporal disaggregation and speciation of the emissions are presented and discussed. The resulting emission system is evaluated, and a case study on CO, NO₂, O₃, VOC and PM_2.5 concentrations is conducted to demonstrate its applicability. Moreover, resulting traffic emissions from the Mobile Source Emission Factor Model for Mexico (MOBILE6.2-Mexico) and the MOtor Vehicle Emission Simulator for Mexico (MOVES-Mexico) models are integrated in the tool to assess and compare their performance. NO_x and VOC total emissions modelled are reduced by 37% and 26% in the MCMA when replacing MOBILE6.2-Mexico for MOVES-Mexico traffic emissions. In terms of air quality, the system composed by the Weather Research and Forecasting model (WRF) coupled with the HERMES-Mex and CMAQ models properly reproduces the pollutant levels and patterns measured in the MCMA. The system's performance clearly improves in urban stations with a strong influence of traffic sources when applying MOVES-Mexico emissions. Despite reducing estimations of modelled precursor emissions, O₃ peak averages are increased in the MCMA core urban area (up to 30ppb) when using MOVES-Mexico mobile emissions due to its VOC-limited regime, while concentrations in the surrounding suburban/rural areas decrease or increase depending on the meteorological conditions of the day. The results obtained suggest that the HERMES-Mex model can be used to provide model-ready emissions for air quality modelling in the MCMA.

Spring pollen and related allergies in southern Spain

Over the last 10 years, there has been an increase in pollen allergies throughout Europe; this trend is clearly reflected in this study carried out in Córdoba (southern Spain) over 7 consecutive years, which recorded important increases in the concentrations of certain pollen types of particular interest in this city, together with an increase in the number of patients with pollinosis visiting the Allergy Unit at Córdoba's Reina Sofía University Hospital. The purpose of this study was to ascertain whether these two trends were related. Sampling was carried out from 1984 to 1990, using a Burkard spore trap placed at a height of approximately 15 m on a building situated in the city center. The trend towards an annual increase in the concentration of pollen grains was positive in all cases, although very slight for Quercus and very marked for Olea europaea. However, a different pattern of behavior was recorded with respect to the correlation between pollen concentration and cases of pollinosis, a correlation which varied according to taxa.

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and enalapril

A 69-year-old woman with a history of diabetes and hypertension, was referred to the Hospital of Laredo because of hyponatraemia. She had weakness and slight dyspnoea with no evidence of extracellular fluid volume depletion or oedema. Serum sodium level on admission was 125 mol l-1, plasma osmolality 270 mosmol kg-1, simultaneous urine osmolality was 580 mosmol kg-1 and urine sodium 32.6 mmol l-1. She had been treated with enalapril (20 mg) daily for 4 months. She was diagnosed with the Syndrome of inappropriate secretion of antidiuretic hormone (SIADH) that was reversed after cessation of treatment with enalapril and reappeared on reintroduction of the drug at the same daily doses.

Differential respiratory patterns induced by opioids applied to the ventral medullary and dorsal pontine surfaces of cats

The purpose of the present study was to make a functional dissection of the respiratory action of opioids, by their restricted application to the ventral surface of the medulla oblongata and to the rostro-dorsal surface of the pons in cats. The effects were compared to those induced after intracerebroventricular (i.c.v.) injection. Two mu-agonists, morphine and D-Ala2-Me-Phe4-Met(O)ol5-enkephalin (FK-33824), and the delta-agonist D-Ala2-D-Leu5-enkephalin (DADLE) were used. When applied to the ventral medullary surface, the opioids selectively depressed the generating mechanisms for tidal volume and the response to CO2, whereas the frequency was increased. The application to the rostral dorsal surface of the pons was followed by a selective depression of the respiratory frequency. By intracerebroventricular administration, the opioids depressed both the tidal volume and frequency generating mechanisms. The effects were always reversed by naloxone. The pontine structures were more sensitive to the action of the opioids than were the medullary centres. These findings suggest that the opioids can interact with different populations of respiratory neurones and that the respiratory output differs depending on the group of neurones selectively affected and the function they subserve in regulating respiratory activity.

Participation of pontine structures in the respiratory action of opioids

The respiratory action of morphine, D-Ala2-D-Leu5-enkephalin, and D-Ala2-Me-Phe4-Met(O)ol5-enkephalin, restrictively applied to the dorso-rostral surface of the pons, was studied in anesthetized cats. Frequency was selectively and dose-dependently depressed, down to apnea, whereas tidal volume and its response to CO2 either remained unchanged or were increased. Similar effects were observed in vagotomized and decerebrate cats. From these and previous (1) results, it can be concluded that the medullary and pontine structures related to respiration are differentially affected by opioids. Pontine nuclei are more sensitive to opioid depression and account for changes in frequency, whereas medullary depression results in reduction of tidal volume and CO2 sensitivity.

Respiratory responses to opiates applied to the medullary ventral surface

The participation of the medullary structures in the total respiratory effect of opiates was studied by restricting the access of the delta-agonist D-ala2-D-leu5-enkephalin and the mu-agonist D-ala2-Me-Phe4-Met (O) ol5-enkephalin, to the ventral medullary surface, and by comparing their responses with those induced after i.c.v. administration. The medullary structures were more resistant to the overall depressant action. The opioids in the medulla depressed preferentially the tidal volume and the CO2-responsivity whereas the i.c.v. injections affected severely the frequency. No qualitative differences were found between the effects of the delta- and mu-agonist. It is concluded that both, medullary and supramedullary structures are involved in the respiratory response to opiates, but they participate with unique functions in the overall respiratory effect.

Cardiovascular effects of intracerebroventricular injection of dopamine after selective MAO inhibition in rats

Intracerebroventricular injection of dopamine (30-300 micrograms) caused a dose-dependent reduction in the blood pressure and cardiac rate of anaesthetized rats. Inhibition of MAO-type A with clorgyline enhanced the vasodepressant effect while it reversed the bradycardiac effect. Deprenyl, a MAO-type B inhibitor, did not modify the cardiovascular effects of dopamine injected into the cerebral ventricles. The persistent hypotensive action of dopamine in clorgyline-pretreated rats was abolished by the central blockade of alpha-adrenoreceptors with intracerebroventricular injection of phentolamine, whereas haloperidol given by the same route did not affect the hypotensive response. The results suggest that dopamine centrally affects cardiovascular regulation, either after conversion into noradrenaline, or through a direct stimulation of central alpha-adrenoceptors.

Morphine, pentobarbital and naloxone in the ventral medullary chemosensitive areas: differential respiratory and cardiovascular effects

Morphine, naloxone and pentobarbital were applied to ventral chemosensitive areas (M and S) and nonchemosensitive areas (pyramids) of the medulla oblongata in anesthetized cats. The respiratory and cardiovascular responses were studied. Morphine and pentobarbital caused a rapid respiratory depression when they were applied for 10 min to the areas M and S; they were inactive in the pyramidal area. The area M was more sensitive than area S to both drugs, because a more rapid and higher depression was induced in the area M. Morphine affected preferentially the respiratory frequency, whereas pentobarbital depressed tidal volume, regardless of the area tested. On the other hand, only pentobarbital reduced the blood pressure, the area S being more sensitive than the area M. When the contact of morphine was extended to 30 min, slight respiratory depression was also observed in the pyramidal area. Naloxone applied to the areas M and S reversed the effects of morphine only partially; i.v. injection of the antagonist was required to achieve full reversion and overshoot. The data show that the described areas are sensitive to opiate and nonopiate drugs. They seem to behave either as chemosensitive structures interacting differentially with drugs, or as areas that allow a rapid access of drugs into some centers deeply located in the brain stem.

Respiratory effects of beta-endorphin, D-Ala2-met-enkephalinamide, and Met-enkephalin injected into the lateral ventricle and the pontomedullary subarachnoid space

The respiratory effects of Met-enkephalin (900 microgram), D-Ala2-Met-enkephalinamide (10 microgram), and beta-endorphin (10 microgram) were studied and compared in lightly anesthetized cats, after injection into the lateral ventricle and into the pontomedullary subarachnoid space. The 3 peptides injected into the lateral ventricle induced equidepressant effects on respiration, but the duration of action and the involvement of either frequency or tidal volume varied considerably. Met-enkephalin was shorter-acting (45 min) than both D-Ala2-Met-enkephalinamide and beta-endorphin (over 5 h). The depression induced by beta-endorphin was preceded by a long-lasting stimulation of frequency. The effects were antagonized by i.v. naloxone, but the antagonism was not complete in one third of the animals. In the pontomedullary subarachnoid space, beta-endorphin failed to depress respiration significantly whereas Met-enkephalin induced an immediate and short-acting depression (15 min), and D-Ala2-Met-enkephalinamide depressed respiration for 2-4 h in a biphasic pattern. It is concluded that: (1) respiration is depressed by the 3 opiate peptides; (2) the effects of beta-endorphin on respiration, at the dose used in this study, are secondary to other actions on higher brain structures; and (3) Met-enkephalin and D-Ala2-Met-enkephalinamide seem to affect pontomedullary areas located near the ventral surface, although they may also interact with respiratory structures located more deeply in the brain stem.

Inhibition of the activity of the respiratory and vasomotor centers by centrally administered 5-hydroxytryptamine in cats

The influence of 5-hydroxytryptamine (5-HT) on the activity of the respiratory and vasomotor centers was studied by injecting 5-HT into the lateral and fourth ventricles of lightly anaesthetized cats. 50 and 500 mu g of 5-HT injected into the lateral ventricle induced a shortlasting increase in frequency and/or tidal volume followed by a prolonged and dose-dependent reduction of frequency, tidal volume and minute volume, concurrent with an increase in end expiratory CO2. The CO2 responsiveness of the respiratory center was depressed and the blood pressure levels were also lowered. All these effects were markedly enhanced by monoamine oxidase inhibition with i.v. tranylcypromine injected 75 min prior to 5-HT. 50 mu g of 5-HT injected into the fourth ventricle induced a depression of respiration similar to that observed in the lateral ventricle studies, with the exception that the early stimulation was abolished.