Olive Leaf Polyphenols (OLPs) Stimulate GLUT4 Expression and Translocation in the Skeletal Muscle of Diabetic Rats.

Skeletal muscles are high-insulin tissues responsible for disposing of glucose via the highly regulated process of facilitated glucose transporter 4 (GLUT4). Impaired insulin action in diabetes, as well as disorders of GLUT4 vesicle trafficking in the muscle, are involved in defects in insulin-stimulated GLUT4 translocation. Since the Rab GTPases are the main regulators of vesicular membrane transport in exo- and endo-cytosis, in the present work, we studied the effect of olive leaf polyphenols (OLPs) on Rab8A, Rab13, and Rab14 proteins of the rat soleus muscle in a model of streptozotocin (SZT)-induced diabetes (DM) in a dose-dependent manner. Glucose, cholesterol, and triglyceride levels were determined in the blood, morphological changes of the muscle tissue were captured by hematoxylin and eosin histological staining, and expression of GLUT4, Rab8A, Rab13, and Rab14 proteins were analyzed in the rat soleus muscle by the immunofluorescence staining and immunoblotting. OLPs significantly reduced blood glucose level in all treated groups. Furthermore, significantly reduced blood triglycerides were found in the groups with the lowest and highest OLPs treatment. The dynamics of activation of Rab8A, Rab13, and Rab14 was OLPs dose-dependent and more effective at higher OLP doses. Thus, these results indicate a beneficial role of phenolic compounds from the olive leaf in the regulation of glucose homeostasis in the skeletal muscle.

NUTRITIONAL RISK SCREENING IN GASTROENTEROLOGICAL PATIENTS AT THE RIJEKA UNIVERSITY HOSPITAL CENTRE.

Malnutrition is usually related to some diseases such as inflammatory bowel disease, chronic pancreatitis, chronic liver disease and malignant tumors. It is characterized by weight loss, protein deficiency, and deficit of specific nutrients. The aim was to estimate the prevalence of nutritional risk among 160 gastrointestinal patients by use of the Nutritional Risk Screening (NRS-2002) score at hospital admission and discharge. The patients stayed in the hospital between 5 and 15 days or longer. Results showed that 40% of patients at admission and 36.2% at discharge were malnourished. There were 53.1% of patients with recognized malnutrition at admission that received nutritional support, whereas at discharge 34.4% of patients at risk were not dietary supported. Malnourished patients were significantly older, had lower body mass index, longer hospital stay and higher rate of malignant diseases than properly nourished patients. Regular screening for malnutrition should be conveyed in hospitals as to provide appropriate dietary support for all patients at risk.

Segmental fibre type composition of the rat iliopsoas muscle.

The iliopsoas of the rat is composed of two muscles - the psoas major muscle and the iliacus muscle. The psoas major muscle arises from all the lumbar vertebrae and the iliacus muscle from the fifth and sixth lumbar vertebrae and ilium. Their common insertion point is the lesser trochanter of the femur, and their common action is the lateral rotation of the femur and flexion of the hip joint. Unlike humans, the rat is a quadruped and only occasionally rises up on its hind legs. Therefore, it is expected that the fibre type composition of the rat iliopsoas muscle will be different than that of humans. The iliopsoas muscle of the rat is generally considered to be a fast muscle. However, previous studies of the fibre type composition of the rat psoas muscle showed different results. Moreover, very little is known about the composition of the rat iliacus muscle. The aim of our study was to examine the fibre type composition of the rat iliopsoas muscle in order to better understand the complex function of the listed muscle. The psoas major muscle was examined segmentally at four different levels of its origin. Type I, IIA, IIB and IIX muscle fibres were typed using monoclonal antibodies for myosin heavy chain identification. The percentage of muscle fibre types and muscle fibre cross-sectional areas were calculated. In our study we showed that in the rat iliopsoas muscle both the iliacus and the psoas major muscles had a predominance of fast muscle fibre types, with the highest percentage of the fastest IIB muscle fibres. Also, the IIB muscle fibres showed the largest cross-sectional area (CSA) in both muscles. As well, the psoas major muscle showed segmental differences of fibre type composition. Our results showed changes in percentages, as well as the CSAs of muscle fibre types in cranio-caudal direction. The most significant changes were visible in type IIB muscle fibres, where there was a decrease of percentages and the CSAs from the cranial towards the caudal part of the muscle. From our results it is evident that the rat iliopsoas muscle has a heterogeneous composition and is composed of all four muscle fibre types. Primarily, it is a fast, dynamic muscle with a predominance of fast type IIB muscle fibres with the largest CSAs. The composition of the rat psoas major muscles changes in a cranio-caudal direction, thus pointing to a more postural role of the caudal part of the muscle.

Influence of hyperbaric oxygen treatment on myogenic transcriptional factors of denervated rat muscle.

The aim of this study was to determine whether hyperbaric oxygen (HBo2) treatment influences the expression of transcriptional myogenic factors in denervated rat's extensor digitorum longus muscle. Thus, expressing regulatory myogenic factors MyoD and myogenin were analyzed in denervated muscles (up to 30 days). Second group of denervated rats were afterwards treated with HBO2. Normal, innervated muscles were used as controls. Western blot analysis showed a significant upregulation of MyoD and myogenin proteins in denervated muscle during this period. Denervated muscles of rats exposed to HBO2 treatment had also significant upregulation of both transcriptional factors but the treatment had not altered their expression. The immunohistochemical analysis showed MyoD and myogenin protein expression through this period in the denervated, untreated muscles and in denervated muscles of rats treated with HBO2, too. One month denervation caused a reduction in muscle fiber cross-sectional area. The treatment with HBO2 had not reduced the degree of atrophy. The protocol of hyperbaric oxygenation (HBO) applied in this study had no beneficial effect either on transcriptional myogenic factors or on atrophy of denervated rat muscle.

Effect of hyperbaric oxygen treatment on myogenic transcriptional factors in regenerating rat masseter muscle.

Hyperbaric oxygen (HBO) treatment was shown to be beneficial as an additional treatment for ischemic muscles in crush injuries and ischemia-reperfusion injuries. The purpose of this study was to assess the influence of hyperbaric oxygen treatment on transcriptional myogenic factors during muscle regeneration. Those factors (MyoD, myf5, myogenin, mrf4) are essential for determination and differentiation of skeletal muscle tissue and together with several other factors control gene expression during myogenesis. The process of regeneration in rat masseter muscle was provoked with injection of local anesthetic bupivacaine hydrochloride. Following injection, the animals were treated once daily in hyperbaric chamber from one to ten days and than sacrificed. Immunohistochemical and Western blot analysis of frozen masseter muscle samples showed a transient upregulation of myoD and myogenin transcriptional factors in the muscles of hyperbaric oxygen treated rats and of rats that have not been treated after the injury. HBO treatment had no effect on the expression of MyoD and myogenin transcriptional factors in the regenerating rat masseter muscle.