Carbohydrate-rich supplements can improve nitrogen use efficiency and mitigate nitrogenous gas emissions from the excreta of dairy cows grazing temperate grass.

Temperate pasture species constitute a source of protein for dairy cattle. On the other hand, from an environmental perspective, their high N content can increase N excretion and nitrogenous gas emissions by livestock. This work explores the effect of energy supplementation on N use efficiency (NUE) and nitrogenous gas emissions from the excreta of dairy cows grazing a pasture of oat and ryegrass. The study was divided into two experiments: an evaluation of NUE in grazing dairy cows, and an evaluation of N-NH3 and N-N2O volatilizations from dairy cow excreta. In the first experiment, 12 lactating Holstein × Jersey F1 cows were allocated to a double 3 × 3 Latin square (three experimental periods of 17 days each) and subjected to three treatments: cows without supplementation (WS), cows supplemented at 4.2 kg DM of corn silage (CS) per day, and cows supplemented at 3.6 kg DM of ground corn (GC) per day. In the second experiment, samples of excreta were collected from the cows distributed among the treatments. Aliquots of dung and urine of each treatment plus one blank (control - no excreta) were allotted to a randomized block design to evaluate N-NH3 and N-N2O volatilization. Measurements were performed until day 25 for N-NH3 and until day 94 for N-N2O. Dietary N content in the supplemented cows was reduced by 20% (P < 0.001) compared with WS cows, regardless of the supplement. Corn silage cows had lower N intake (P < 0.001) than WS and GC cows (366 v. 426 g/day, respectively). Ground corn supplementation allowed cows to partition more N towards milk protein compared with the average milk protein of WS cows or those supplemented with corn silage (117 v. 108 g/day, respectively; P < 0.01). Thus, even though they were in different forms, both supplements were able to increase (P < 0.01) NUE from 27% in WS cows to 32% in supplemented cows. Supplementation was also effective in reducing N excretion (761 v. 694 g/kg of Nintake; P < 0.001), N-NH3 emission (478 v. 374 g/kg of Nmilk; P < 0.01) and N-N2O emission (11 v. 8 g/kg of Nmilk; P < 0.001). Corn silage and ground corn can be strategically used as feed supplements to improve NUE, and they have the potential to mitigate N-NH3 and N-N2O emissions from the excreta of dairy cows grazing high-protein pastures.

[Long-term course of patients with myocardial infarction and bundle branch block]. / Evolution à long terme des malades atteints d'infarctus du myocarde avec bloc de branche.

The long-term outcome of myocardial infarction (MI) with bundle branch block (BBB) was studied retrospectively by a direct questionnaire and a registry enquiry in order to define the prognostic significance of data obtained during hospitalisation and to discuss the possible indications of permanent pacing in these patients. Out of 2 720 acute MI hospitalised between October 1969 and April 1977, 231 and BBB (unknown before infarction): 58 right, 53 left and 120 bilateral BBB. 113 patients survived the acute phase of MI and 111 patients were followed up for 72 +/- 24 months: 80 patients died, and 30 survive - a global survival rate of only 13% at 6 years. The post-admission mortality rate was not related to the type of BBB or the site of infarction. It was significantly higher in patients with previous myocardial infarction and in a sub group of patients without advanced AV block in the acute phase who had severe cardiac failure (Classes III and IV, Killip). The hospital mortality was higher in patients with advanced AV block in the acute stage (62,5% compared to 45,9%) in patients without advanced AV block, p < 0,025. On the other hand, the post-admission mortality was not significantly different in these two sub groups (77,8% compared to 69,8% : NS). Stokes-Adams syncope was rarely authentified in the post-admission course of the patients. An increased risk of secondary sudden death directly related to a conduction defect has not been proved. The indications for permanent pacing therefore remain uncertain. They should not be widened further than the indications for permanent pacing in chronic degenerative block.

[Electrophysiological effects of anti-arrhythmia agents in man. Attempt at classification]. / Effets électrophysiologiques des agents antiarythmiaques chez l'homme. Tentative de classification.

The electrophysiological effects of anti-arrhythmic drugs in man may be classified in three groups: -- Group I: comprising drugs whose characteristic action is on the AV node (beta blockers, verapamil, digitalis) The nodal conduction time (A-H interval) and refractory periods are increased. -- Group II: comprising drugs acting on the His-Purkinje system, the AV nodal conduction staying unchanged. This group has two sub-groups. Sub-group A: these drugs delay the His-Prukinje conduction (increased H-V interval). Examples are quinidine, procainamide, disopyramide, ajmaline, chloro-acetyl-ajmaline. In addition these drugs usually increase the atrial refractory periods and those of accessory pathways. Sub-group B: the His-Purkinje conduction is unchanged but the refractory periods are modified: lengthened (bretylium tosylate) or shortened (diphenylhydantoin, lignocaine, mexiletine). -- Group III: which includes amiodarone and aprindine whose effects are mixed: on the one hand AV nodal depression, and on the other, alteration of the His-Purkinje conduction manifested by an increased H-V internal (aprindine) or refractory periods (amiodarone). These preparations also increase the refractory periods of accessory AV pathways and amiodarone increase the refractory periods of the atria. This type of classification could help towards a more rational clinical approach to the use of anti-arrhythmic drugs.

[Electrophysiological study on mexiletine in man with reference to dose-response relation]. / Etude électrophysiologique de la méxilétine chez l'homme avec référence à la relation dose-effet.

The electrophysiological properties of Mexiletine were investigated by endocavitary His Bundle recording and programmed electrical stimulation of the heart in 30 patients. Differing dosage (2, 2.7 and 3.4 mg/kg) were given intravenously in 3 groups of 10 patients. The effects on the length of the sinus cycle, conduction intervals and cardiac refractory periods were observed and the following results obtained : 1. Sinus rhythm increased at all dosages but this effect was much more pronounced with 3.4 mg/kg dosage (--12.8% +/- 2.81% : : % shortening of sinus cycle with respect to the basal cycle +/- SD, p less than 0.005); 2. Atrioventricular nodal conduction time (A-H interval) decreased, the effect being more marked with the larger dose regimes; 3.His-Pirkinje conduction time (H-V interval) unaltered except in 3 cases where it increased by 5 ms after injection of 2.7 mg/kg; 4. Relative refractory period of His-Parkinje system shortened, this effect also being more pronounced with the larger doses ( --3.75 +/- 0.25% :2.7 mg/kg, p less than 0,001; -- 7 +/- 1.46% 3.4 mg/kg, p less than 0.005). In conclusion, the changes observed in the His-Purkinje system after mexiletine were similar to those of Lignocaine and Diphenylhydantoin. The drug also appears to have a marked vagal inhibitory effect as shown by the acceleration of the sinus rhythm and reduced atrioventricular conduction times.

[Cause of death in recent myocardial infarct. Correlation between extent of necrosis and clinical, electrocardiographic and anatomical findings]. / Les causes de la mort dans l'infarctus myocardique récent. Corrélations entre l'etendue de la nécrose et les constatations cliniques, electrocardiographiques et anatomiques.

A retrospective study of 100 case notes of patients who died from a recent myocardial infarction (less than one month before death) has established the causes of death: cardiac failure (52), rupture of the heart (40), major pulmonary emboli (3), primary irreversible ventricular fibrillation (2), unexplained death (3). Study of the extent of the necrosis by the technique of segmentation of the ventricular mass has allowed us to clarify the correlation between the "index of extent" ("i"), an the clinico-pathological findings. It has been noted in particular that those infarctions complicated by cardiogenic shock and/or by bilateral bundle branch block were those with the highest value of index of extent (i = 8.91, i = 9.40); also that cardiac failure and ventricular tachycardia were found in the extensive infarctions (i = 7,33, i = 9.52); also that rupture of the outer wall and pulmonary thromboses complicated infarctions of very small extent (i = 4,80, i = 5,67). It would not seem possible to reduce the hospital mortality of infarctions significantly, since it is essentially linked with circulatory failure caused by extensive necrosis, and with ruptures of the heart which are unpredictable and untreatable.