Impairment of short term memory in rats with hepatic encephalopathy due to bile duct ligation

Hepatic encephalopathy (HE) arises from acute or chronic liver diseases and leads to cognitive deficits. Different animal models for the study of HE have demonstrated learning and memory impairment and a number of neurotransmitter systems have been proposed to be involved in this. Recently, it was described that bile duct-ligated (BDL) rats exhibited altered spatio-temporal locomotor and exploratory activities and biosynthesis of neurotransmitter GABA in brain cortices. Therefore, the aim of this study was to evaluate cognition in the same animal model. Male adult Wistar rats underwent common bile duct ligation (BDL rats) or manipulation of common bile duct without ligation (control rats). Six weeks after surgery, control and BDL rats underwent object recognition behavioral task. The BDL rats developed chronic liver failure and exhibited a decreased discrimination index for short term memory (STM) when compared to the control group. There was no difference in long term memory (LTM) as well as in total time of exploration in the training, STM and LTM sessions between the BDL and control rats. Therefore, the BDL rats demonstrated impaired STM for recognition memory, which was not due to decreased exploration.     

Phospholemman deficiency in postinfarct hearts: enhanced contractility but increased mortality

Phospholemman (PLM) regulates [Na(+) ](i), [Ca(2+)](i) and contractility through its interactions with Na(+)-K(+)-ATPase (NKA) and Na(+) /Ca(2+) exchanger (NCX1) in the heart. Both expression and phosphorylation of PLM are altered after myocardial infarction (MI) and heart failure. We tested the hypothesis that absence of PLM regulation of NKA and NCX1 in PLM-knockout (KO) mice is detrimental. Three weeks after MI, wild-type (WT) and PLM-KO hearts were similarly hypertrophied. PLM expression was lower but fractional phosphorylation was higher in WT-MI compared to WT-sham hearts. Left ventricular ejection fraction was severely depressed in WT-MI but significantly less depressed in PLM-KO-MI hearts despite similar infarct sizes. Compared with WT-sham myocytes, the abnormal [Ca(2+) ], transient and contraction amplitudes observed in WT-MI myocytes were ameliorated by genetic absence of PLM. In addition, NCX1 current was depressed in WT-MI but not in PLM-KO-MI myocytes. Despite improved myocardial and myocyte performance, PLM-KO mice demonstrated reduced survival after MI. Our findings indicate that alterations in PLM expression and phosphorylation are important adaptations post-MI, and that complete absence of PLM regulation of NKA and NCX1 is detrimental in post-MI animals.     

Sources of Protein and Polyunsaturated Fatty Acids of the Diet and Microalbuminuria in Type 2 Diabetes Mellitus

Background: Albuminuria excretion rate above the reference range and below albustix positive proteinuria (20–199 μg/min) is known as microalbuminuria and has been associated with an increased risk of death and progression to renal failure. Besides hyperglicemia and high blood pressure levels, dietary factors can also influence albuminuria.

Objective: To evaluate possible associations of dietary components (macronutrients and selected foods) with microalbuminuria in type 2 diabetic patients.

Methods: In this cross-sectional study, 119 normoalbuminuric [NORMO; 24-h urinary albumin excretion (UAE) < 20 μg/min; immunoturbidimetry] and 62 microalbuminuric (MICRO; UAE 20–199 μg/min) type 2 diabetic patients, attending the Endocrine Division, Hospital de Clínicas de Porto Alegre (Brazil), without previous dietary counseling, underwent 3-day weighed-diet records, and clinical and laboratory evaluation.

Results: MICRO patients consumed more protein (20.5 ± 4.4 vs. 19.0 ± 3.5% of total energy; p = 0.01) with a higher intake from animal sources (14.5 ± 4.7 vs. 12.9 ± 3.8% of total energy; p = 0.015) than NORMO patients. The intakes of PUFAs (8.6 ± 2.9 vs. 9.7 ± 3.3% of total energy; p < 0.03), PUFAs from vegetable sources (7.3 ± 3.4 vs. 8.6 ± 3.7% of total energy; p = 0.029), plant oils [0.2 (0.1–0.6) vs. 0.3 (0.1–0.9) mg/kg weight; p = 0.02] and margarines [3.3 (0–75.7) vs. 7.0 (0–51.7) g/day; p = 0.01] were lower in MICRO than in NORMO. In multivariate logistic regression models, adjusted for age, gender, presence of hypertension and fasting plasma glucose, intake of total protein (% of total energy; OR 1.104; 95% CI 1.008–1.208; p = 0.032) was positively associated with microalbuminuria. The intakes of total PUFAs (% of total energy; OR 0.855; 95%CI 0.762–0.961; p = 0.008), PUFAs from vegetable sources (% of total energy; OR 0.874; 95%CI 0.787–0.971; p = 0.012) and plant oils (mg/kg weight; OR 0.036; 95% CI 0.003–0.522; p = 0.015) were negatively associated with microalbuminuria.

Conclusions: In type 2 diabetic patients, the high intake of protein and the low intake of PUFAs, particularly from plant oils, were associated with the presence of microalbuminuria. Reducing protein intake from animal sources and increasing the intake of lipids from vegetable origin might-reduce the risk of microalbuminuria.     

Inflammasome components Asc and caspase-1 mediate biomaterial-induced inflammation and foreign body response

Implantation of biomaterials and devices into soft tissues leads to the development of the foreign body response (FBR), which can interfere with implant function and eventually lead to failure. The FBR consists of overlapping acute and persistent inflammatory phases coupled with collagenous encapsulation and currently there are no therapeutic options. Initiation of the FBR involves macrophage activation, proceeding to giant cell formation, fibroblast activation, and collagen matrix deposition. Despite the recognition of this sequence of events, the molecular pathways required for the FBR have not been elucidated. We have identified that the acute inflammatory response to biomaterials requires nucleotide-binding domain and leucine-rich repeat-containing 3 (Nlrp3), apoptosis-associated speck-like protein containing CARD (Asc), and caspase-1, as well as plasma membrane cholesterol, and Syk signaling. Full development of the FBR is dependent on Asc and caspase-1, but not Nlrp3. The common antiinflammatory drug aspirin can reduce inflammasome activation and significantly reduce the FBR. Taken together, these findings expand the role of the inflammasome from one of sensing damage associated molecular patterns (DAMPs) to sensing all particulate matter irrespective of size. In addition, implication of the inflammasome in biomaterial recognition identifies key pathways, which can be targeted to limit the FBR.     

Temporal progression of the host response to implanted poly(ethylene glycol)-based hydrogels

Poly(ethylene glycol) (PEG) hydrogels hold great promise as in vivo cell carriers for tissue engineering. To ensure appropriate performance of these materials when implanted, the host response must be well understood. The objectives for this study were to characterize the temporal evolution of the foreign body reaction (FBR) to acellular PEG-based hydrogels prepared from PEG diacrylate precursors when implanted subcutaneously in immunocompentent c57bl/6 mice by (immuno)histochemical analysis and gene expression. Compared with a normal FBR elicited by silicone (SIL), PEG hydrogels without or with a cell adhesion ligand RGD elicited a strong early inflammatory response evidenced by a thick band of macrophages as early as day 2, persisting through two weeks, and by increased interleukin-1β expression. PEG-only hydrogels showed a slower, but more sustained progression of inflammation over PEG-RGD. Temporal changes in gene expression were observed in response to PEG-based materials and in general exhibited, elevated expression of inflammatory and wound healing genes in the tissues surrounding the implants, while the expression patterns were more stable in response to SIL. While a stabilized FBR was achieved with SIL and to a lesser degree with PEG-RGD, the PEG-only hydrogels had not yet stabilized after 4 weeks. In summary, PEG-only hydrogels elicit a strong early inflammatory reaction, which persists throughout the course of the implantation even as a collagenous capsule begins to form. However, the incorporation of RGD tethers partially attenuates this response within 2 weeks leading to an improved FBR to PEG-based hydrogels.     

Characteristics of murine histidinaemia and its potential for genetic manipulation.

BACKGROUND: Histidinaemia is an autosomal recessive disorder affecting the hepatic enzyme histidine ammonia lyase (histidase) resulting in elevated plasma and urinary histidine and is prototypic of a series of hepatic cytosolic enzyme defects. AIMS: To characterise the physiology of murine histidinaemia with respect to histidine excretion and catabolism, and explore the potential for manipulating cellular and whole body histidase metabolism by gene transfer. MATERIALS AND METHODS: We studied his/his mice which have a G to A substitution in the gene encoding histidase, using both in vitro transduction of isolated hepatocytes by lipofection with wild-type histidase cDNA, and in vivo transduction of whole liver using a retroviral construct. RESULTS AND CONCLUSION: Histidase cDNA expression restored histidase activity in vivo and in vitro towards normal levels, demonstrated both at the cellular level and by whole body metabolic studies, establishing the potential of this model for the development of new gene therapeutic approaches.     

The role of food restriction on CCl4-induced cirrhosis model in rats.

Effects of food restriction on susceptibility to the toxic effect of some chemicals are controversial. In order to identify an exposure model that could maximize cirrhosis and minimize mortality rate, this study aimed to evaluate the effect of food restriction on tetrachloride carbon (CCl(4))-induced cirrhosis model in rats. Fifty-three male Wistar rats received CCl(4) 0.25 ml/kg weekly intragastrically once a week. Thirty-three had 44% food restriction (group 1); 10 rats had 25% food restriction (group 2); and 10 rats received ad libitum food (group 3). After 10 weeks, the animals were sacrificed and liver sections were collected for histology. Of the 53 animals enrolled for the study, 22 (41.5%) died before completing 10-week CCl(4). Mortality rate was significantly higher in group 1 compared to other groups (p<0.05). Cirrhosis was significantly more prevalent in group 1 than in group 3 (p<0.01), but without significant difference between groups 1 and 2 (p=0.624). We concluded that food restriction is an important issue to be considered when establishing a CCl(4)-induced cirrhosis model in rats. Moreover, there is an ideal range of food intake that predisposes to liver damage without increasing mortality leading to a more effective model.