EFFECT OF EXERCISE ON GLUTAMINE SYNTHESIS AND TRANSPORT IN SKELETAL MUSCLE FROM RATS

• 1 Reductions in plasma glutamine are observed after prolonged exercise. Three hypotheses can explain such a decrease: (i) high demand by the liver and kidney; (ii) impaired release from muscles; and (iii) decreased synthesis in skeletal muscle. The present study investigated the effects of exercise on glutamine synthesis and transport in rat skeletal muscle.
• 2 Rats were divided into three groups: (i) sedentary (SED; n = 12); (ii) rats killed 1 h after the last exercise bout (EX‐1; n = 15); and (iii) rats killed 24 h after the last exercise bout (EX‐24; n = 15). Rats in the trained groups swam 1 h/day, 5 days/week for 6 weeks with a load equivalent to 5.5% of their bodyweight.
• 3 Plasma glutamine and insulin were lower and corticosterone was higher in EX‐1 compared with SED rats (P < 0.05 and P < 0.01, respectively). Twenty‐four hours after exercise (EX‐24), plasma glutamine was restored to levels seen in SED rats, whereas insulin levels were higher (P < 0.001) and costicosterone levels were lower (P < 0.01) than in EX‐1. In the soleus, ammonia levels were lower in EX‐1 than in SED rats (P < 0.001). After 24 h, glutamine, glutamate and ammonia levels were lower in EX‐24 than in SED and EX‐1 rats (P < 0.001). Soleus glutamine synthetase (GS) activity was increased in EX‐1 and was decreased in EX‐24 compared with SED rats (both P < 0.001).
• 4 The decrease in plasma glutamine concentration in EX‐1 is not mediated by GS or glutamine transport in skeletal muscle. However, 24 h after exercise, lower GS may contribute to the decrease in glutamine concentration in muscle.

     

Spinal cord transection modifies ileal fluid and electrolyte transport in rats

Spinal cord injury (SCI) is associated with severe autonomic changes, including inhibition of gastrointestinal (GI) motility. GI motility changes are known to affect electrolytes transport and these changes have not been adequately studied after SCI. We studied the ileal permeability to fluid and electrolytes in rats submitted to experimental spinal cord transection (SCT), between T4 and T5, throughout the first week after SCT. SCT increased ileal secretion of Na+ (P<0.05) and decreased the Cl(-) absorption during the first week post SCI (P<0.05). Water transport was also significantly altered, leading to increased water secretion following the Na+ gradient. Ileal secretion of K+ was significantly increased 1 and 7 days after spinal cord injury. To our knowledge, the present findings are the first direct evidence that SCT alters ileal electrolyte transport in rats. Further studies are necessary to evaluate the mechanisms involved in this phenomenon.     

Histological evaluation of biocompatibility of lyophilized bovine pericardium implanted subcutaneously in rats

Abstract:  This article aims at investigating in vivo evaluation of lyophilization procedure on the biocompatibility of bovine pericardium treated with glutaraldehyde (GA). The bovine pericardium was fixed with 0.5% glutaraldehyde during 10 days and preserved in 4% formaldehyde (FA). Two groups of samples were prepared from treated membranes: Group 1, nonlyophilized samples and Group 2, lyophilized samples. Male Sprague-Dawley rats (4 weeks after birth) were anesthetized (pentobarbital sodium 25 mg/kg of body weight) and in each one were implanted subcutaneously in the dorsal region a sample from Group 1 and another from Group 2. These samples were explanted after 30 days for histological analysis. No intercurrences took place after the surgery. No differences ( P  > 0.05) in the calcification, granulomatous reaction, mononuclear infiltration, and granulation tissue development was observed between both groups. The implanted lyophilized samples presented a trend for a reduced inflammatory reaction. Lyophilization of the bovine pericardium does not seem to increase the above listed tissue reaction.     

Concomitant pleural and disseminated tuberculosis in AIDS: immune response or HIV infection compartmentalization?

Although, pleural (PT) and disseminated tuberculosis (DT) have been considered as extreme endpoints of the Th1-Th2 immunological spectrum of the Mycobacterium tuberculosis infection, these conditions can occur together. The presence of PT and DT could be explained by (1) PT as primary condition, with progression of HIV infection possibly leading to dissemination of bacilli located in the pleura; (2) preexisting PT, with reinfection at lower LTCD4+ count explaining the DT form; (3) simultaneous acute PT and DT, considering immune compartmentalization phenomena in pleura. There are several important aspects of the immune response and its compartmentalization in co-infected patients with tuberculosis and HIV. PT and DT should not be always considered as extremes of the immunological response against M. tuberculosis, both diseases together may be explained after the understanding of compartmentalization of immune response. Associations between these entities are not so rare, while they remain incompletely explained. This brief review discusses several points of this contradictory association.     

Abnormal deposition of collagen/elastic vascular fibres and prognostic significance in idiopathic interstitial pneumonias

BACKGROUND: Vascular remodelling has recently been shown to be a promising pathogenetic indicator in idiopathic interstitial pneumonias (IIPs). AIM: To validate the importance of the collagen/elastic system in vascular remodelling and to study the relationships between the collagen/elastic system, survival and the major histological patterns of IIPs. METHODS: Collagen/elastic system fibres were studied in 25 patients with acute interstitial pneumonia/diffuse alveolar damage, 22 with non-specific interstitial pneumonia/non-specific interstitial pneumonia and 55 with idiopathic pulmonary fibrosis/usual interstitial pneumonia. The Picrosirius polarisation method and Weigert's resorcin-fuchsin histochemistry and morphometric analysis were used to evaluate the amount of vascular collagen/elastic system fibres and their association with the histological pattern of IIPs. The association between vascular remodelling and the degree of parenchymal fibrosis in usual interstitial pneumonia (UIP) was also considered. RESULTS: The vascular measurement of collagen/elastic fibres was significantly higher in UIP than in the lungs of controls, and in those with diffuse alveolar damage and those with non-specific interstitial pneumonia. In addition, the increment of collagen/elastic fibres in UIP varied according to the degree and activity of the parenchymal fibrosis. The most important predictors of survival in UIP were vascular remodelling classification and vascular collagen deposition. CONCLUSION: A progressive vascular fibroelastosis occurs in IIP histological patterns, probably indicating evolutionarily adapted responses to parenchymal injury. The vascular remodelling classification and the increase in vascular collagen were related to survival in IIP and possibly play a role in its pathogenesis. Further studies are needed to determine whether this relationship is causal or consequential.     

Effects of nutrients on immunomodulation in patients with severe COVID-19: Current knowledge

Recent research has demonstrated that critically ill patients with coronavirus disease 2019 (COVID-19) show significant immune system dysregulation. Due to that, some nutrients that influence immunomodulation have been suggested as a form of treatment against the infection. This review collected the information on the impact of vitamins on the prognosis of COVID-19, with the intention of facilitating treatment and prevention of the disease risk status in patients. The collected information was obtained using the PubMed electronic database by searching for articles that relate COVID-19 and the mechanisms/effects of the nutrients: Proteins, glucose, lipids, vitamin B12, vitamin D, calcium, iron, copper, zinc, and magnesium, including prospective, retrospective, and support articles. The findings reveal an optimal response related mainly to omega-3, eicosapentaenoic acid, docosahexaenoic acid, calcium, and iron that might represent benefits in the treatment of critically ill patients. However, nutrient supplementation should be done with caution due to the limited availability of randomized controlled studies.