Medical Therapies for the Treatment of Pulmonary Arterial Hypertension: How Do We Choose?

Oxygen-sensitivity and Pulmonary Selectivity of Vasodilators as Potential Drugs for Pulmonary Hypertension

Current approved therapies for pulmonary hypertension (PH) aim to restore the balance between endothelial mediators in the pulmonary circulation. These drugs may exert vasodilator effects on poorly oxygenated vessels. This may lead to the derivation of blood perfusion towards low ventilated alveoli, i.e., producing ventilation-perfusion mismatch, with detrimental effects on gas exchange. The aim of this study is to analyze the oxygen-sensitivity in vitro of 25 drugs currently used or potentially useful for PH. Additionally, the study analyses the effectiveness of these vasodilators in the pulmonary vs. the systemic vessels. Vasodilator responses were recorded in pulmonary arteries (PA) and mesenteric arteries (MA) from rats and in human PA in a wire myograph under different oxygen concentrations. None of the studied drugs showed oxygen selectivity, being equally or more effective as vasodilators under conditions of low oxygen as compared to high oxygen levels. The drugs studied showed low pulmonary selectivity, being equally or more effective as vasodilators in systemic than in PA. A similar behavior was observed for the members within each drug family. In conclusion, none of the drugs showed optimal vasodilator profile, which may limit their therapeutic efficacy in PH.

Supplementary value of ensiled brewers spent grain used as replacement to cotton seed cake in the concentrate diet of lactating crossbred dairy cows

The aim of this study was to investigate the effects of ensiled brewers spent grain (BSG) when used as replacement to cotton seed cake in the concentrate diet of lactating crossbred dairy cows. Eight early lactating F1 Boran X Friesian cows were used in a short term feeding trial to identify optimum level of ensiled BSG substitution of cotton seed cake (0, 33, 66, and 100%) in iso-nitrogenous diets. A 4 × 4 double Latin square design was used to analyze the data set generated from the feeding and digestibility trials. The results showed that as the level of ensiled BSG replacement to cotton seed cake increased, daily intakes on the natural pasture hay: 8.1 (T1) vs 7.6 (T2), 6.0 (T3), and 5.1 (T4); total feed dry matter: 14.6 (T1) vs 14.0 (T2), 12.9 (T3), and 12.2 (T4); crude protein (CP): 2.0 (T1) vs 1.9 (T2), 1.8 (T3), and 1.7 (T4); neutral detergent fiber (NDF): 8.4 (T1) vs 8.2 (T2), 7.4 (T3), and 6.8 (T4); and acid detergent fiber (ADF): 4.8 (T1) vs 4.5 (T2), 3.8 (T3), and 3.3 (T4) decreased (P < 0.05). However, estimated metabolizable energy (EME) intakes (129 vs 126) and body weight of the animals (465 vs 467) on the control diet and dietary T2 (33% BSG replacement for cottonseed cake) were comparable (P > 0.05). Thereafter, differences in daily EME intakes and body weight changes decreased with an increase in the level of ensiled BSG in the concentrate diet (P < 0.05) compared with both the control and animals on T2. Ensiled BSG, on the other hand, substantially improved (P < 0.05) total ration's apparent digestibility of dry matter (DM): 629 (T1) vs 659 (T3), 686 (T4); CP: 676(T1) vs 690(T3), 738(T4); NDF: 524 (T1) vs 544 (T3), 581 (T4); and ADF: 341 (T1) vs 350 (T2), 392 (T3), 440(T4) and daily milk yield: 14.5 (T1) vs 15.4 (T4) and milk production efficiency: 0.98 (T1) vs 1.11 (T3) and 1.26 (T4). So, ensiled BSG can be recommended to fully replace cotton seed cake from the concentrate diet of lactating dairy cows under local conditions. Additional research is needed to minimize and/or avoid body weight loss, milk fat, and total solids.

Evaluation of the milk urea content in relation to milk production and composition in dairy cows

The aim of this study was to evaluate the milk urea content along with the dynamics of lactation and milk components in production dependency in Holstein dairy cows. Evaluation of daily milk yield in relation to milk urea presented a positive regression dependency, which was the strongest in early lactation (r = 0.860; P < 0.001), decreasing in mid lactation (r = 0.329; P < 0.001) and late lactation (r = 0.261; P < 0.001). Evaluation of milk protein in relation to milk urea showed a negative regression dependency, which was the strongest in early lactation (r = -0.850; P < 0.001), decreasing in mid lactation (r = -0.819; P < 0.001) and late lactation (r = -0.679; P < 0.001). The somatic cell counts in relation to milk urea confirmed a negative regression dependency in early lactation (r = -0.635; P < 0.05) and mid lactation (r = -0.818; P < 0.05), but no significance was found in late lactation. The results of the study confirm the influence of production factors (milk quantity and milk components) on the milk urea content. Dependencies found between the production, milk components and milk urea are applicable for the evaluation of protein nutrition and metabolic transformation of nutrients in dairy cows.

Relationship between portopulmonary hypertension and splenectomy: Mayo Clinic experience and review of published works

AIM

Portopulmonary hypertension is a serious complication of portal hypertension that can lead to right heart failure and death. To our knowledge, an association between portopulmonary hypertension and prior splenectomy has not been described previously. The goals of this study were to describe the frequency of splenectomy in portopulmonary hypertension and compare selected parameters between portopulmonary hypertension subgroups.

METHODS

This is a retrospective analysis of patients diagnosed with portopulmonary hypertension between 1 January 1988 and 30 June 2015 at Mayo Clinic (Rochester, MN, USA). We compared age, sex, right ventricle systolic pressure by echocardiography, and right heart catheterization measurements/calculations among subgroups of portopulmonary hypertension patients with splenectomy and/or autoimmune liver disease (autoimmune hepatitis/primary biliary cirrhosis/primary sclerosing cholangitis).

RESULTS

The cohort consisted of 141 patients, of whom 8 (6%) had a history of splenectomy prior to the development of portopulmonary hypertension. Twenty-seven (19%) portopulmonary hypertension patients had autoimmune liver disease, and 5 of 8 (62.5%) splenectomized portopulmonary hypertension patients had autoimmune liver disease. No significant difference was noted in right heart catheterization measurements/calculations between splenectomized and non-splenectomized portopulmonary hypertension patients. Right ventricle systolic pressure by echocardiography was significantly higher in those splenectomized.

CONCLUSIONS

Prior history of splenectomy in portopulmonary hypertension was 6% in this cohort. The combination of autoimmune liver disease and splenectomy in portopulmonary hypertension was not uncommon. History of splenectomy in patients with portal hypertension and/or autoimmune liver disease may have clinical implications.