Evidence for a new major gene influencing meat quality in pigs

The present investigation primarily deals with the inheritance of a pigmeat quality trait, the Napole technological yield (RTN), a measure of cooked weight to fresh weight. This trait as well as lean percentage at 100 kg liveweight and fattening length from 20 to 100 kg liveweight were recorded on 3459 offspring from 67 sires and 433 dams, and 3052 offspring from 64 sires and 405 dams in Penshire (P66) and Pen Ar Lan (P77) composite lines respectively. The hypothesis of a major 2-allele locus contributing to RTN was tested by use of a segregation analysis method. Highly significant likelihood ratios (mixed vs. polygenic transmission models) lead us to conclude that a major gene RN- exerting an unfavourable effect on RTN is segregating in both lines. Maximum likelihood estimates of the parameters under the hypothesis of mixed (monogenic + polygenic) inheritance show that the difference between the means of the 2 homozygotes amounts to about 3 phenotypic standard deviations of the trait, whereas the complete dominance of RN- cannot be rejected. The frequency of RN- is about 0.6 in both lines. These results are discussed in connection with the previously reported 'Hampshire effect' on pigmeat quality, as the Hampshire breed is a common component of the foundation stock of the 2 composite lines under study.

Influence of training on blood lipids and coagulation

Even if the effects of physical training on secondary prevention are controversial, it is known that exercise may influence several of the risk factors for coronary heart disease (CHD). One of the most important is cholesterol. Studies conducted to determine the influence of training on lipid profile have shown in normals, as well as in CHD patients, a favourable influence: a small decrease in total cholesterol and low-density lipoprotein cholesterol, and an increase in high-density lipoprotein cholesterol. These results are obtained after prolonged and intensive training. The influence of training on coagulation is more controversial and less well known. During short bouts of exercise the following changes are generally observed: an increase in platelet count and platelet aggregation (the effects on platelet adhesiveness and activation are controversial), potentiation of coagulation with an increase in factor VIII, and an increase in fibrinolytic activity due to an increase in plasminogen activator level. The effects of training have been less well studied. It is supposed that training could diminish the clotting potentiation observed during short exercise. Fibrinolysis is also increased in these conditions. If the influence of training on blood lipid profile may be considered as favourable in secondary prevention, no study has yet assessed the role of training on coagulation factors in secondary prevention.

Prognostic significance of angina pectoris recurring soon after myocardial infarction

The prognostic significance of an early occurrence, or recurrence, of angina pectoris after myocardial infarction was studied in 254 patients (221 male, 33 female; mean age 58 +/- 11 years). During the in-hospital rehabilitation program, 41 patients (16%) had anginal pain. The mean follow-up was 21 months (range 12-33 months). Among the 254 patients, 21 died, five had recurrent myocardial infarction, 13 had unstable angina, and 22 underwent aortocoronary bypass surgery. An early recurrence of angina pectoris was predictive of combined (medical + surgical) events (21 patients, P less than 0.05), medical events (11 patients, P less than 0.05) and surgical events (10 patients, P less than 0.001), but failed to predict individual death (six patients), recurrent myocardial infarction (two patients) or unstable angina (three patients). Of the events that occurred in the 254 patients, 34% were predicted by the early recurrence of angina pectoris. Early post-infarction angina was observed more frequently in older patients and patients with previous history of angina pectoris. This represents an important prognostic factor after myocardial infarction, which defines a high-risk group of patients requiring further investigation and appropriate therapeutic approaches.

[Prognostic value of the exercise test after myocardial infarction]

A stress test performed in the early stage after myocardial infarction enables to evaluate directly or indirectly three of the main prognosis factors: alteration of ventricular function, presence of ventricular arrhythmias, residual ischemia. This test, performed around the 15th day, after previous anti-angina treatment have been discontinued, is only done in the absence of the classic contra-indications. It permits to detect abnormalities: electrical positivity (with or without pain), disorder of the ventricular rhythm, abnormality of the blood pressure profile, low stress level. The predictive value of these abnormalities has been the subject of many studies. Although all the results are not in agreement, each one of these abnormalities seems to carry an increased risk of cardiac occurrences after myocardial infarction. In addition, an early stress test enables to detect pluritroncular coronary lesions with, however, an average sensitivity. Thallium scintigraphy in conjunction with a stress test improves, however, the performances of this test. The advantage of an early stress test is the rapid screening of high risk patients who should benefit from additional exploratory measures and possibly of myocardial revascularization procedures.

Acute effects of trimetazidine evaluated by exercise testing

A single dose of 60 mg trimetazidine (the normal daily dose) improved exercise capacity in angina pectoris, as reflected by an increase in the duration of exercise, total work performed, and improvement in ECG signs of ischaemia. All these effects occurred without any detectable chronotropic or vasomotor effect. The importance of this study is to demonstrate that these beneficial effects, already well-recognized after chronic administration of 20 mg three times a day, also occur after a single administration equivalent to the normal daily dose.

[Treatment of unstable angina. A randomized double-blind study of propranolol, diltiazem and molsidomine]

A randomized, multicentric, double blind study attempted to compare in 41 patients hospitalized for unstable angina, the efficacy of diltiazem (D) 240 mg/day, propranolol (P) 160 mg/day and molsidomine (M) 8 mg/day. The patients included in the study presented one or several spontaneous angina episodes accompanied by a transient and significant lowering of ST and/or an inverted T wave without necrosis. The evaluation criteria were the occurrence of new angina pain and electrical alterations on a continuous Holter for 5 days. 11 patients received diltiazem, 13 patients received propranolol and 15 patients received molsidomine (including an early death). Clinically, the number of painful episodes per day and per patient goes, in an average, from 1.2 to 0.23 diltiazem, from 2.2 to 0.44 for propranolol and from 2.2 to 0.45 for molsidomine. Pain disappeared on the 5th day in 54.5 per cent of patients under diltiazem, 58.8 per cent of patients under propranolol and 53.5 per cent of patients under molsidomine. Electrically, the number of ischemic accidents per day and per patient was 0.45 under diltiazem, 2.12 under propranolol (0.53 in excluding one patient with latent angina) and 0.81 under molsidomine. The number of patients without any ischemic accident was 63.6 per cent under diltiazem, 53.8 per cent under propranolol and 40 per cent under molsidomine. In conclusion, diltiazem, propranolol, and molsidomine have a comparable efficacy in unstable angina. The association of these medications could have a synergistic effect.

[Ergometric effects of a single administration of trimetazidine]

The effects on exercise capacity of a single oral dose of 60 mg of trimetazidine were studied during a double-blind, placebo controlled cross-over study. Ten patients with stable angina and angiographically proven coronary artery lesions underwent ergometric bicycle exercise tests before and two hours after administration of the drug. A blood sample, for trimetazidine levels, was taken at the end of the recovery period. The homogeneity of the group and the lack of significance of the order of administration were established by cross-over analysis of the "control" tests and the "treated" tests. As compared with placebo, a statistically significant difference was noted after trimetazidine in the following parameters: total work (+31%, P less than 0.02), duration of exercise (+17%, P less than 0.02), percentage of the predicted maximal heart rate reached (+4%, P = 0.05), time to 1 mm ST segment depression (+17%, P less than 0.05) and degree of ST depression at maximum exercise level of the first control test (-31%, P less than 0.05); there was no significant difference in heart rate, blood pressure at rest and rate-pressure product during exercise between treatment and placebo. Two patients showed no response to trimetazidine. In the eight patients who did respond, there was a correlation factor of 0.73 between the plasma levels of trimetazidine and the increase in work performed. In conclusion, a single 60 mg dose of trimetazidine improves exercise tolerance and delays the ischaemic threshold during exercise without any detectable peripheral haemodynamic effects.

[The effects of trimetazidine on ergometric parameters in exercise-induced angina. Controlled multicenter double blind versus placebo study]

The antianginal effect of trimetazidine was assessed by a controlled multicentre double-blind versus placebo trial. The study included 32 males, average age 59.5 years, with stable angina of effort. The stability of angina was determined by two exercise stress tests performed at the beginning and at the end of a 15 day pre-selection period under placebo. The patients included in the trial were given 3 tablets a day of either trimetazidine (20 mg per tablet) or of placebo for one month. At the end of the treatment period the patients underwent a third exercise stress test. Comparing the results of exercise testing before and after treatment by a Mann and Whitney test, a statistically significant improvement with trimetazidine was demonstrated with respect to placebo for three parameters: total work increased from 4200 +/- 372 to 5620 +/- 387 Kpm in the trimetazidine group compared to 4191 +/- 399 to 4564 +/- 431 Kpm for placebo (p = 0.012); the duration of exercise increased from 10.2 +/- 0.5 to 12.1 +/- 0.5 minutes with trimetazidine compared to 10.2 +/- 0.5 to 10.7 +/- 0.5 with placebo (p = 0.016); the period to 1 mm ST depression increased from 8.3 +/- 0.6 to 9.8 +/- 0.5 minutes with trimetazidine compared to 8.4 +/- 0.5 to 9.0 +/- 0.7 minutes with placebo (p = 0.034). These results show that signs of ischaemia are delayed by trimetazidine. There were no significant changes in peripheral haemodynamics at rest or on effort. The antianginal action of trimetazidine seems therefore to be unrelated to a chronotropic or vasomotor effect and could be related to a mechanism of cellular regulation.

[Intravenous labetalol in normotensive coronary patients. Effects on hemodynamics and myocardial metabolism]

The haemodynamic and myocardial metabolic effects of intravenous Labetalol were studied in 7 normotensive coronary patients with at least one significant stenosis on the left anterior descending artery. The study consisted of 5 successive observation periods: basal (I); during atrial pacing at the theoretical maximal heart rate or when anginal pain occurred (II); return to basal conditions (III); 20 minutes after an injection of 1.5 mg/kg of Labetalol over 3 minutes into the pulmonary artery (IV); during repeat atrial pacing at the rate achieved during phase II (V). There was no significant difference between phases I and III except for a slightly faster heart rate in phase III. The effects of Labetalol were assessed by comparing the results during phases III and IV between phases II and V and by analysing the variations between phases I, II, IV and V. In comparison with basal conditions (phase III), Labetalol (phase IV) induced a slight decrease in cardiac output (p less than 0.05), a decrease in aortic pressure and systemic arterial resistances (p less than 0.01) and of the double product. Coronary sinus flow did not change but myocardial oxygen consumption fell by an average of 11% (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

[Acute hemodynamic and coronary effects of captopril in chronic cardiac failure]

The acute effects of captopril on haemodynamics, coronary flow and myocardial metabolism were studied in 12 patients with chronic severe cardiac failure (primary cardiomyopathy: 10 cases; ischaemic: 2 cases) in functional Classes III or IV of the NYHA. All patients were male and their average age was 51.3 +/- 14.1 years (range 27 to 68 years). Measurements were carried out under basal conditions and 90 minutes after a single dose of 50 mg (5 cases) or 100 mg (7 cases) of captopril. Captopril administration leads to an increase in cardiac index from 2.05 +/- 0.32 to 2.34 +/- 0.35 l/min/m2 (p less than 0.05) and a greater increase in systolic index from 23.9 +/- 6.7 to 29.8 +/- 6.9 ml/syst/m2 (p less than 0.01), because the heart rate decreased slightly (p less than 0.05). These changes were the result of a decrease in afterload: mean aortic pressure fell from 85 +/- 11.8 to 68 +/- 19.6 mmHg (p less than 0.01) and systemic arterial resistance fell from 2 886 +/- 745 to 2 010 +/- 610 dynes/cm-5/sec/m-2 (p less than 0.01). Captopril also led to a fall in venous tone, i.e. pre-load: left ventricular end diastolic pressure fell from 26.9 +/- 6.1 to 20.8 +/- 6.6 mmHg: p less than 0.01. There was no change in contractility as shown by the absence of variation of the V.max (0.92 +/- 0.18 under basal conditions, and 0.90 +/- 0.15 after 90 minutes).(ABSTRACT TRUNCATED AT 250 WORDS)

[Dissection of the ascending aorta after aortic valve replacement]

Three patients who underwent aortic valve replacement had dissection of the ascending aorta 7 months, 2 years and 15 years after surgery. This is a rare complication of aortic valve replacement (11 reported cases). Its incidence estimated from the literature would appear to be less than 1% of all aortic valve replacements. It occurs in both cases of stenosis and regurgitation (4 aortic regurgitations, 2 aortic stenosis, 5 mixed aortic valve disease) and is seen in ball and cage (7 cases), tilting disc (3 cases) and bioprosthesis (1 case). Six of these patients had hypertension. The role of the initial surgery for valve replacement in secondary aortic dissection is discussed. Aortic clamping and cannulation can cause immediate dissection but may also damage the aortic wall, leading to the risk of secondary dissection. An aneurysm of the ascending aorta was observed in 5 Cases at surgery; in 3 cases, the aorta was dilated without true aneurysm; in 3 other cases the aorta was considered to be macroscopically normal. The integrity aorta is sometimes difficult to confirm and a macroscopically normal of the aorta may have fragile aortic walls, especially in cases of aortic regurgitation due to valvular dysplasia and forms frustres of Marfan's syndrome, and are associated with a risk of secondary dissection. The appearances of the aorta at aortic valve replacement influence the choice of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Non-invasive quantification of aortic regurgitation by Doppler echocardiography

This study was undertaken to assess the contribution of Doppler echocardiography to the quantification of aortic valve regurgitation. Ultrasound examination was performed by recording aortic arch blood flow from the suprasternal notch. A non-invasive index of valve regurgitation was obtained by calculating the ratio between the maximal amplitude of forward flow during systole and the amplitude of retrograde flow during diastole measured at the onset of the R wave of the electrocardiogram. This index was compared with semiquantitative data derived from supravalvular aortography in 93 patients. In pure aortic regurgitation (67 patients) the results showed a high correlation coefficient between Doppler and angiographic estimates. In cases of associated aortic valve stenosis there were problems in the accurate estimation of systolic blood flow which led to global overestimation in general of the degree of regurgitation and considerable lack of precision in individual patients. But in general Doppler echocardiography appeared to be a successful technique to quantify pure aortic regurgitation.

[Non-invasive study of aortic insufficiency by Doppler echocardiography]

The possibilities of diagnosis and quantification of aortic regurgitation by pulsed Doppler analysis of blood flow in the aortic arch were examined in 60 patients aged between 9 and 67 years old. Aortic flow curves were recorded from the suprasternal area with the sample volume positioned at the junction of the horizontal part of the aortic arch and the descending aorta. Normal flow curves are characterised by an anterograde systolic wave with a brief proto-diastolic reflux. In aortic regurgitation holodiastolic reflux is observed. An index of regurgitation may be calculated from the ratio of the amplitude of end diastolic reflux measured on the R wave of th ECG and the maximal amplitude of anterograde systolic flow. This ratio eliminates the factor related to the incident angle between the ultrasound beam and the direction of blood flow. The values of this ratio were compared to the semi quantitative assessment of aortic regurgitation from ascending aortic angiography. The only false negatives were observed in patients with negligible regurgitation (grade I). One false positive result was obtained in a patient in whom it was difficult to obtain the recording and in whom the value of the ratio was very low (0,02). Global specificity was 91 p. 100 and sensitivity was 82 p. 100. The sensitivity for average or severe regurgitation was 100 p. 100. The correlation coefficient between the Doppler index or regurgitation and the semi quantitative angiographic estimation was 0,69. In patients with pure aortic regurgitation the correlation reached 0,85 (p less than 0,001). The differences between the different groups then became highly significant.