Respiratory pandemic and indoor aeraulics of classrooms.

Respiratory pandemics, such as COVID19, may be transmitted by several modes. The present work focuses on the transmission through small droplets released by people from their mouth by breathing, speaking, coughing, sneering, and possibly aspirated by other people around through their respiration. An analysis of droplet evolution in simplified situations shows that the droplets reach very quickly a quasi-equilibrium temperature before encompassing an isothermal evaporation process. The removal of droplets from suspension is thus piloted by balance between evaporation and sedimentation. It is shown that ambient relative humidity is a major factor influencing the lifetime of droplets and the distance they may travel. As a consequence, and independently of any other health consideration linked to ambient humidity, it is seen that a dry air is a favourable factor for limiting risk of contamination from COVID19. Further investigation is made using computational fluid dynamics (CFD) in a classroom geometry. Several ventilation strategies are investigated: classical regulatory mechanical ventilation, open window natural ventilation and displacement natural ventilation. Ventilation has several effects which influence contamination risk: by introducing fresh air, it reduces droplet concentration; humidity released by human occupants is also limited. However, these effects are not uniform in space, and depend on ventilation strategy. Application of a dose-effect model calibrated for COVID19 to CFD results allows to estimate contamination risk. It is shown that contamination risk is higher for regulatory mechanical ventilation, and may be reduced, using natural ventilation in the absence of wind, by a factor 2.3 to nearly 3 when the teacher is sick, and by a factor 6 to 500 when a student is sick. In the presence of wind, the reduction factor is as high as 13 when the teacher is sick and 17 when a student is sick.

[Thymomectomy by minimally invasive surgery. Comparative study videosurgery versus robot-assisted surgery]. / Traitement des thymomes par chirurgie mini-invasive. Étude comparative vidéochirurgie versus voie robot-assistée.

OBJECTIVES: To report the results of minimally invasive surgery in patients with stage I or II thymoma in the Masaoka classification. The reference technique is partial or complete thymectomy by sternotonomy. METHODS: A retrospective single-center study of a prospective database including all cases of thymoma operated from April 2009 to February 2015 by minimally invasive techniques: either videosurgery (VATS) or robot-assisted surgery (RATS). The surgical technique, type of resection, length of hospital stay, postoperative complications and recurrences were analysed. RESULTS: Our series consisted of 22 patients (15 women and 7 men). The average age was 53 years. Myasthenia gravis was present in 12 patients. Eight patients were operated on by VATS and 14 patiens by RATS. There were no conversions to sternotomy and no perioperative deaths. The mean operating time was 92min for VATS and 137min for RATS (P<0.001). The average hospital stay was 5 days. The mean weight of the specimen for the VATS group was 13.2 and 45.7mg for the RATS group. Twelve patients were classified Masaoka stage I and 10 were stage II. According to the WHO classification there were 7 patients type A, 5 type AB, 4 type B1, 4 type B2 4 and 2 type B3. As proposed by the Group ITMIG-IASLC in 2015 all patients corresponded to group I. The mean follow-up period was 36 months. We noted 3 major perioperative complications according to the Clavien-Dindo classification: one pneumonia, one phrenic nerve paralysis and one recurrent laryngeal nerve palsy. We observed one case of local recurrence at 22 months. Following surgery 4 patients were treated with radiotherapy and 2 patients with chemotherapy. CONCLUSIONS: The minimally invasive route is safe, relatively atraumatic and may be incorporated in the therapeutic arsenal for the treatment of Masaoka stage I and II thymoma as an alternative to conventional sternotomy. RATS and VATS are two minimally invasive techniques and the results in the short and medium term are acceptable. The clinical advantages of one over the other are sifficult to establish. RATS could handle larger and more complex lesions in view of the weight and size of the operating instrument.

One-year clinical outcome after minimally invasive direct coronary artery bypass.

BACKGROUND: Minimally invasive coronary artery bypass (MIDCAB) is a new surgical technique by which the left internal mammary artery is anastomosed under direct visualization to the left anterior descending artery without cardiopulmonary bypass. METHODS AND RESULTS: We followed all 274 patients who underwent MIDCAB from the time it was introduced at a single center. In-hospital and 1-year clinical events were source-documented and adjudicated. The in-hospital major acute cardiac event rate was 2.2%; this included a 1.1% mortality rate. At 1 year, the respective rates were 7.8% and 2. 5%. When compared with the initial 100 procedures, the subsequent 174 procedures had shorter vessel occlusion times (10+/-5 versus 14+/-6 minutes; P:=0.009), times to extubation (6+/-3 versus 14+/-10 hours; P:<0.001), and lengths of hospital stay (2.1+/-1.9 versus 3. 2+/-3.1 days; P:=0.04). Cumulative 1-year adverse cardiac events were 11% in the initial 100 cases and 6% in the subsequent 174 cases (P:=0.17). CONCLUSIONS: Excellent clinical results can be achieved with the MIDCAB technique. The clinical adverse event rate may decrease with accumulated experience.

Stroke after coronary artery bypass: incidence, predictors, and clinical outcome.

BACKGROUND AND PURPOSE: Early postoperative stroke is a serious adverse event after coronary artery bypass grafting (CABG). This study sought to investigate risk factors, prevalence, and prognostic implications of postoperative stroke in patients undergoing CABG. METHODS: We investigated the predictors of postoperative stroke (n=333, 2%) in 16 528 consecutive patients who underwent CABG between September 1989 and June 1999 in our institution. Predictors of postoperative stroke were identified by logistic regression analysis. RESULTS: Among the preoperative and postoperative factors, significant correlates of stroke included (1) chronic renal insufficiency (P<0.001), (2) recent myocardial infarction (P=0.01), (3) previous cerebrovascular accident (P<0.001), (4) carotid artery disease (P<0.001), (5) hypertension (P<0.001), (6) diabetes (P=0.001), (7) age >75 years (P=0.008), (8) moderate/severe left ventricular dysfunction (P=0.01), (9) low cardiac output syndrome (P<0.001), and (10) atrial fibrillation (P<0.001). Postoperative stroke was associated with longer postoperative stay (11+/-4 versus 7+/-3 days for patients without stroke, P<0.001) and with higher in-hospital mortality (14% versus 2.7% for patients without stroke; P<0.001). CONCLUSIONS: Stroke after CABG is associated with high short-term morbidity and mortality. Increased stroke risk can be predicted by preoperative and postoperative clinical factors.

Atrial fibrillation after beating heart surgery.

Postoperative atrial fibrillation (AF) is a frequent adverse event after coronary artery bypass grafting (CABG) and may negatively affect the early clinical outcome. We sought to investigate the risk factors, prevalence, and prognostic implications of postoperative AF in patients submitted to CABG without cardiopulmonary bypass (off-pump). The study population comprised 969 patients, 645 men (67%) and 324 women (33%) who had off-pump CABG at the Washington Hospital Center from January 1987 to May 1999. Preoperative AF patients were excluded (n = 15). Two hundred six patients (age 69 +/- 10 years, 137 men [66%]) developed AF, whereas 763 patients (age 61 +/- 12 years, 508 men [67%]) did not. Predictors of AF included age >75 years (odds ratio [OR] 3.0, 95% confidence interval [CI] 1.9 to 4.5; p <0.001), history of stroke (OR 2.1, CI 1.2 to 3.7; p = 0. 007), postoperative pleural effusion requiring thoracentesis (OR 3.2, CI 1.0 to 9.4; p = 0.03), and postoperative pulmonary edema (OR 5.1, CI 1.2 to 21; p = 0.02). Minimally invasive direct CABG was associated with a lower incidence of AF (OR 0.4, CI 0.3 to 0.7; p <0. 001). AF was associated with a prolonged postoperative hospital stay (9 +/- 6 days AF vs 6 +/- 5 days no AF, p <0.001). In-hospital mortality was significantly higher in AF patients (3% AF vs 1% no AF, p = 0.009). Patients with persistent AF had a higher postoperative in-hospital stroke rate than patients without persistent AF (9% vs 0. 6%, p <0.001). AF after beating heart surgery is associated with a higher in-hospital morbidity, mortality, and prolonged hospital stay. A minimally invasive surgical approach (minimally invasive direct CABG) is associated with a lower risk of AF.

Prevention of atrial fibrillation after cardiac surgery: the significance of postoperative oral amiodarone.

STUDY OBJECTIVES: Atrial fibrillation (AF) is a common occurrence after cardiac surgery (10 to 53%) that contributes to increased length of stay and hospital cost. Recent evidence suggests that treatment with amiodarone may provide safe and effective prophylaxis against AF in many patients undergoing cardiac operations. This study sought to investigate whether oral amiodarone administered postoperatively would reduce the incidence of postoperative AF. DESIGN: Prospective nonrandomized cohort study. PATIENTS AND PARTICIPANTS: In this prospective study, 1,196 consecutive patients who underwent various open-heart procedures with cardiopulmonary bypass between July 1999 and February 2000 received oral amiodarone, 400 mg bid, from the transfer to the cardiovascular recovery room until the day of hospital discharge, or up to 7 days postoperatively. The incidence of AF in this group of patients was compared with a group of 1,246 patients who underwent cardiac surgery with cardiopulmonary bypass in the preceding 8-month period (November 1998 to June 1999) at the same institution without receiving amiodarone postoperatively. SETTING: Tertiary health-care center. MEASUREMENT AND RESULTS: AF developed in 294 patients (25%) in amiodarone-treated group and in 385 patients (31%) in the control group (p = 0.001). In multivariate logistic regression analysis, oral amiodarone treatment emerged as an independent predictor of lower risk of AF (odds ratio, 0.7; 95%; 95% confidence interval, 0.6 to 0.9; p = 0.002) and shorter hospital length of stay (odds ratio, 0.8; 95% confidence interval, 0.5 to 0.9; p = 0.006). CONCLUSIONS: Postoperative oral amiodarone treatment is a safe and effective regimen associated with a reduced incidence of new-onset AF and decreased length of hospital stay. Prospective randomized trials are needed to evaluate the benefits of amiodarone treatment relative to its side effect profiles.

Experimental infection of gnotobiotic mice with Campylobacter jejuni: colonisation of intestine and spread to lymphoid and reticulo-endothelial organs.

Axenic and monoxenic C3H mice were used to develop an animal model for enteroinvasiveness and translocation of Campylobacter jejuni. After oral administration of 10(7)-10(8) viable cells of C. jejuni on day 0 (D0), bacterial colonisation was followed quantitatively during 23 days by counting free luminal bacteria and tissue-associated bacteria in the duodenum, ileum and colon. The kinetics of bacterial colonisation were the same in axenic and monoxenic mice; bacteria were more numerous in distal than in proximal intestinal segments. Electronmicroscope studies of axenic infected mice showed C. jejuni free in the intestinal lumen on D2 and D7, and adhering to microvilli or included in enterocyte vacuoles in the colon on D2 without inflammatory reaction; C. jejuni was isolated from mesenteric lymph nodes until D23, but from blood, spleen, liver and bile until D1 only. In monoxenic infected mice, C. jejuni was found from D1 to D4 in mesenteric lymph nodes and Peyer's patches, whereas the associated bacterium (Clostridium perenne) was never cultured from any organs. On the basis of our observations in this gnotobiotic model, C. jejuni appears to be an enteroinvasive bacterium with a particular affinity for lymphoid organs.

Management strategy for simultaneous carotid endarterectomy and coronary revascularization.

BACKGROUND: The occurrence of significant carotid artery disease in patients requiring coronary artery bypass grafting (CABG) results in a dilemma regarding the best surgical management. Our philosophy has been to perform simultaneous carotid endarterectomy and CABG. We reviewed the efficacy of this therapy in patients treated at a large community-based hospital. METHODS: During a 6-year period, from 1990 to 1996, 88 patients underwent simultaneous carotid endarterectomy and CABG. All patients underwent preoperative four-vessel arch arteriography and standard coronary angiography. The principal indications for combined procedures were the need for CABG and (1) symptomatic carotid artery disease; (2) internal carotid artery stenosis of 80% or more, with or without contralateral disease; or (3) an ulcerated, unstable internal carotid artery lesion, regardless of degree of stenosis. The average patient age was 68 years, and there was a 3:1 male-to-female predominance. All procedures were performed with the patients under general anesthesia. The carotid endarterectomy was performed first, and an intraluminal shunt was used in all patients. RESULTS: The average degree of stenosis on the operated side was 86.2%. An average of 3.6 coronary bypasses per patient were performed. Morbidity included four strokes (4.5%). There were no perioperative myocardial infarctions. There were three hospital deaths (3.4%). The combined permanent stroke and mortality rate was 6.8%. Univariate predictors of stroke were an elevated serum creatinine level, a pulmonary complication, and left main coronary artery disease. Univariate predictors of hospital death were stroke, an elevated serum creatinine level, peripheral vascular disease, and left main coronary artery disease. Multivariate predictors of a prolonged hospitalization were stroke, an elevated serum creatinine level, and a pulmonary complication. Eighty-five patients (96.6%) were discharged and alive at 30 days. CONCLUSIONS: In the context of the indications we used to select patients for simultaneous carotid endarterectomy and CABG, the combined permanent stroke and mortality rate was less than 7%. Our management strategy identified patients that were at increased surgical risk as a result of advanced carotid and coronary artery disease. In our practice, simultaneous carotid endarterectomy and CABG is the preferred surgical approach for these high-risk patients and results in a low in-hospital morbidity and mortality using a single anesthetic and hospitalization.

MIDCABG followed by a gastrointestinal operation in the same anesthetic setting.

Cardiovascular complications continue to be a significant source of morbidity and mortality in patients having noncardiac operations. This especially is true in patients with known coronary artery disease facing intraabdominal operations. Minimally invasive direct coronary artery bypass grafting allows coronary artery grafting without cardiopulmonary bypass or a median sternotomy incision. Also, in combination with angioplasty (the "hybrid procedure"), it is possible to offer complete revascularization with far less surgical trauma. We present 2 cases of patients who had minimally invasive direct coronary artery bypass grafting followed by major gastrointestinal operations in the same anesthetic setting.

Beating heart versus conventional single-vessel reoperative coronary artery bypass.

BACKGROUND: Reoperative (redo) coronary artery bypass grafting (CABG) with cardiopulmonary bypass (on-pump) is associated with a higher morbidity and mortality than first-time CABG. It is unknown, however, whether CABG without cardiopulmonary bypass (off-pump) may yield an improved clinical outcome over conventional on-pump redo CABG. METHODS: We compared the perioperative outcomes of patients with single-vessel disease who underwent on-pump (n = 41) versus off-pump (n = 91) redo CABG between April 1992 and July 1999. The two groups were similar with respect to baseline characteristics and risk stratification: mean Parsonnet scores were 26 +/- 9 for on-pump versus 24 +/- 8 for off-pump patients (p = nonsignificant). RESULTS: On-pump redo patients had a higher rate of postoperative transfusions (58% on-pump versus 27% off-pump, p = 0.001), prolonged ventilatory support (17% on-pump versus 4% off-pump, p = 0.03), and a higher rate of postoperative atrial fibrillation (29% on-pump versus 14% off-pump, p = 0.04). On-pump redo CABG was also associated with prolonged postoperative length of stay (8 +/- 4 days on-pump versus 5 +/- 2 days off-pump, p < 0.001). In-hospital mortality was significantly higher in on-pump than in off-pump patients (10% versus 1%, p = 0.03). CONCLUSIONS: Single-vessel off-pump redo CABG can be performed safely with a lower operative morbidity and mortality than on-pump CABG and an abbreviated hospital stay compared with conventional on-pump redo CABG.

Beating heart surgery in octogenarians: perioperative outcome and comparison with younger age groups.

BACKGROUND: Octogenarians have higher morbidity and mortality rates (9% to 16%) after coronary artery bypass grafting with cardiopulmonary bypass, compared with younger patients. METHODS: We compared the perioperative outcome and hospital stay after coronary artery bypass grafting without cardiopulmonary bypass (off-pump) from January 1987 to May 1999, among patients older than 80 years (n = 71), patients between 70 and 79 years (n = 228), and patients whose age ranged from 60 to 69 years (n = 296). In comparison with younger patients, more octogenarians were female (51% versus 39% in patients aged 70 to 79 years and 35% in those aged 60 to 69 years, p = 0.04), they had previous myocardial infarction more frequently (48% versus 47% versus 34%, respectively, p = 0.008), and were operated on urgently (69% versus 56% versus 52%, respectively, p = 0.04). RESULTS: Postoperative complications that were significantly higher in octogenarians compared with younger groups included pneumonia (6% in octogenarians versus 2% in patients aged 70 to 79 years and 0% in patients aged 60 to 69 years, p = 0.001) and atrial fibrillation (47% versus 32% versus 21%, respectively, p<0.001). By multivariate logistic regression analysis, age over 80 years was an independent predictor of prolonged hospital stay (odds ratio = 2.7, 95% confidence interval, 1.4 to 5, p<0.001). The in-hospital mortality rate was higher in octogenarians (6% versus 3% for 70 to 79 year-olds and 0.3% for 60 to 69 year-olds, p = 0.006). CONCLUSIONS: When appropriately applied in patients older than 80 years, off-pump coronary artery bypass grafting can be done with acceptable postoperative morbidity, mortality, and hospital stay.

Coronary artery bypass without cardiopulmonary bypass.

The purpose of this article is twofold: to describe our technique for performing coronary artery bypass grafting without cardiopulmonary bypass (off pump) and to demonstrate that this operation is safe, in terms of mortality and certain indices of morbidity. Very little has been published in regard to off-bypass operations. From 1985 through 1990, 220 patients underwent operation off bypass; 220 on-pump controls were retrospectively matched for number of grafts, left ventricular function, and date of operation. Groups were compared in terms of mortality and ten indicators of morbidity. The same analysis was performed for ten subgroups. We found no statistically significant difference between groups in mortality (off pump, 1.4% [3/220]; on pump, 2.4% [5/220]), which held across all subgroups. Patients undergoing operation off pump required blood far less often (not transfused: off pump, 72.7% [160/220]; on pump, 54.6% [116/220]; p = 0.005 by Fisher's exact test), and the low output state occurred statistically less frequently off pump (off pump, 5.5% [12/220]; on-pump, 12.7% [28/220]; p = 0.01 by Fisher's exact test). Further research should be directed to which subgroups can be operated on to advantage off pump and which, if any, groups of patients should be confined to on-bypass operations.

Coronary revascularization of the circumflex system: different approaches and long-term outcome.

BACKGROUND: Minimally invasive direct coronary artery bypass, without cardiopulmonary bypass, through a left lateral thoracotomy approach (lateral MIDCAB), is a safe alternative to coronary artery bypass surgery using cardiopulmonary bypass (on-pump CABG) of the circumflex system via median sternotomy. However, it is unknown whether lateral MIDCAB may yield an improved long-term outcome over the conventional on-pump median sternotomy approach. METHODS: We compared the perioperative outcomes of patients undergoing lateral MIDCAB (n = 34) versus conventional on-pump CABG of the circumflex system (n = 16) from June 1996 to July 1999. The two groups were similar with respect to baseline characteristics and risk stratification. Patients who required only one or two grafts for complete revascularization were included. RESULTS: Lateral MIDCAB patients had a lower need than on-pump CABG patients for intraoperative (12% MIDCAB vs 43% on-pump CABG, p = 0.03) and postoperative transfusions (29% vs 69%, p = 0.01), had fewer neuropsychologic changes (0% vs 19%, p = 0.03), and had a lower rate of postoperative atrial fibrillation (12% vs 44%, p = 0.02). Lateral MIDCAB was also associated with a significantly lower postoperative length of stay (5 +/- 2 vs 7 +/- 3 days, p = 0.02). Actuarial survival at a mean period of follow-up of 19 +/- 11 months was 97% for the lateral MIDCAB versus 88% for the on-pump CABG group (p = 0.6). Event-free survival was 88% for lateral MIDCAB versus 81% for on-pump CABG (p = 0.1). CONCLUSIONS: Lateral MIDCAB may safely be performed in patients with isolated coronary artery disease of the circumflex system with improved early morbidity and an abbreviated hospital stay compared with conventional median sternotomy on-pump CABG.

Benign astrocytic and oligodendrocytic tumors of the cerebral hemispheres in children.

The authors review 42 consecutive cases of benign astrocytic and oligodendrocytic tumors of the cerebral hemispheres in children undergoing surgery in the pediatric service of the Hôpital des Enfants Malades between 1975 and 1987. Epilepsy was the presenting sign in 76% of the children and remained the only clinical sign at diagnosis in 62%. Partial or complex partial seizures were observed in half of the cases, but other seizure types were also frequent. Diagnosis of the tumor as the etiological agent rested upon the results of computerized tomography or magnetic resonance imaging. Postoperative mortality (5%) and morbidity (16%) rates were low. The postoperative intelligence quotient was above 80 in 71% of the patients, and 77% of the children had no major problem in school. Although only two of the 42 patients were given postoperative radiotherapy, there were no recurrences in 82% of the survivors. The actuarial probability of nonrecurrence of the tumor was 95% at 5 years. Three patients with recurrent tumor underwent further surgery and are, at the present time, recurrence-free. The incidence of epilepsy fell from 76% before surgery to 19% after removal of the tumor alone; therefore, intraoperative electrocorticography and resection of the electrically abnormal cortex at the time of the first surgical procedure do not appear necessary. It is possible that tumor removal restores a mechanism that limits the spread of seizures and, thus, the clinical manifestations of epilepsy. Benign astrocytic and oligodendrocytic tumors of the cerebral hemispheres in children should not be treated with adjuvant radiotherapy, at least initially.

Neuropeptide Y normalizes renin secretion in adrenalectomized rats without changing blood pressure.

In the periphery, neuropeptide Y is present in plasma, in the adrenal medulla as well as in sympathetic nerve endings and in the juxtaglomerular apparatus. The aim of the present study was to assess the effect of this peptide on renin secretion. Normotensive rats were adrenalectomized or sham-operated and made hypertensive with methylprednisolone acetate (20 mg/kg s.c. once weekly). Deoxycorticosterone pivalate (10 mg/kg s.c. once weekly) was also given to prevent mineralocorticoid deficiency. Two weeks after initial surgery, 12 adrenalectomized and 8 sham-operated conscious rats were infused for 30 min with neuropeptide Y (0.1 micrograms/min) whereas 8 other adrenalectomized and 9 sham-operated conscious rats received under similar conditions the vehicle of neuropeptide Y (10 microliter/min). Neither before nor during the infusions was there a significant difference in blood pressure and heart rate between the 4 groups of animals. Plasma renin activity, measured at the end of the infusion, was 30.5 ng/ml/hr in the adrenalectomized group receiving vehicle and 6.3 ng/ml/hr in that infused with neuropeptide Y (p less than 0.001). This latter value did not differ from that found in sham-operated rats. These results suggest that neuropeptide Y may play an important role in regulating renin secretion.

Congenital ciliary aplasia in two siblings. A primitive disregulation of ciliogenesis?

Congenital ciliary aplasia was demonstrated in two siblings with clinical history of primary ciliary dyskinesia. Ultrastructural histochemistry of successive bronchial biopsies revealed the predominance of immature mucous cells and the total absence of ciliated or preciliated cells in the respiratory epithelium. This original disorder may represent a unique variant of primary ciliary dyskinesia with primitive disregulation of ciliogenesis.

Nasal eosinophilia in children: its use in the nasal allergen provocation test.

This pediatric cytological and clinical study aimed at assessing the value of nasal eosinophilia during nasal provocation tests for identifying an offending allergen. The population studied comprised 50 children aged from 4 to 18 yr; 39 of these had well-characterized allergic rhinitis, which in 21 cases was combined with asthma, and the remaining 11 had nonatopic chronic rhinitis. Nasal secretions, collected by nose blowing, were stained with May-Grünwald-Giemsa or Wright stain. The percentage of nasal eosinophils was obtained by examining the cells in the whole slides. Counts were carried out on secretions collected before challenge, after insufflation of saline solution (for verification), and 40 min after insufflation into each nostril of an allergen (housedust mite extract). The nasal provocation test was considered positive when insufflation of the allergen increased nasal eosinophilia by more than 10%, provided that the prechallenge proportion of eosinophils was less than 50%. No increase in specific bronchial resistance was noted. These results indicate that nasal provocation tests are safe, even in asthmatic children.

[Normalization of renin secretion by neuropeptide Y in adrenalectomized rats with glucocorticoid-induced hypertension]. / Normalisation de la sécrétion de rénine par le neuropeptide Y chez les rats surrénalectomisés avec hypertension induite par les glucocorticoïdes.

In the periphery, neuropeptide Y is present in the circulation, in the adrenal medulla as well as at the level of nerve endings and of the juxtaglomerular apparatus. The aim of the present study was to assess the effect of this neuropeptide on renin secretion. Normotensive rats were biadrenalectomized or sham-operated and made hypertensive with methylprednisolone acetate (20 mg/kg s.c. once weekly). Deoxycorticosterone pivalate (10 mg/kg s.c. once weekly) was also given to prevent mineralocorticoid deficiency. Two weeks after that initial surgery 12 adrenalectomized rats and 8 sham-operated rats were infused for 30 min with neuropeptide Y (0.1 microgram/min) whereas 8 adrenalectomized rats and 9 sham-operated rats received in similar conditions the vehicle of neuropeptide Y (10 microliters/min). At that time, the rats were conscious and there was no significant difference in blood pressure and heart rate between the 4 groups of rats. At the end of the experiment, adrenalectomized rats exhibited a markedly stimulated renin-angiotensin system. Neuropeptide Y made it possible to normalize plasma renin activity in these rats, thus suggesting that neuropeptide Y plays an important role in regulating renin secretion.

[Ultrastructural alterations of the alveolar walls capillaries by injection of histamine (author's transl)]. / Modifications ultrastructurales de la barrière alvéolo-capillaire sous l'effet de l'histamine.

Histamine chlorhydrate was intravenously injected to Guinea pigs (7 microgram/kg). Alterations of the alveolar walls capillaries were by electronic microscopy studied 1.5, 12 and 15 minutes after injection. It was observed a rapid dilator effect associated with an opening of the endothelial cells tight junctions, an increasing in the size and turnover of pinocytic vesicles, an enlargement and a loss of homogeneity of the basal membrane and an edema of type I pneumocytes. In the last group of animals, lesions reversibility is characterized by a beginning of closing of endothelial cells junctions and of edema resorption. These morphological findings point out the local effect of histamine on the pulmonary capillary microcirculation and show the decrease of resistance and the increase of permeability of the capillaries.