Serine/Threonine Protein Phosphatase 5 - a Double-edged Sword - in the Progression towards Diabetes

Type 2 diabetes mellitus is increasing at an alarming rate worldwide. In the development and progression of type 2 diabetes mellitus, the insulin-producing pancreatic β-cells are commonly exposed to a hyperglycemic and hyperlipidemic environment, in which the levels of reactive oxygen species are elevated. In turn, reactive oxygen species can trigger an apoptotic response, by activating mitogenactivated protein kinase signaling networks, leading to β-cell death. When the functional β-cell mass is reduced to a level that, can no longer maintain euglycemia, type 2 diabetes mellitus is manifested. Therefore, there is a need to find new antidiabetic drugs that are able to protect the loss of β-cell mass and in so doing prevent and treat diabetes. This thesis aimed at investigating the possible protective roles of serine/threonine protein phosphatase 5 (PP5) in this context. We generated a PP5-deficient mouse line to evaluate the biological actions of PP5. Isolated mouse embryonic fibroblasts from mice lacking PP5 (Ppp5c-/-) and their wild-type littermates (Ppp5c+/+) were exposed to DNA damage-inducing agents to investigate the role of PP5 in response to genotoxic stress. Pancreatic islets isolated from both Ppp5c+/+ and Ppp5c-/- mice, and MIN6 cells treated with shortinterfering RNA targeting PP5, were exposed to H2O2 or palmitate to test the hypothesis that PP5 acts to suppress apoptotic signaling in β-cells. Ppp5c+/+ and Ppp5c-/- mice were placed on either a standard diet or high-fat diet for ten weeks to examine the role of PP5 in a diabetic environment. Our data revealed that the PP5-deficient mice were viable and fertile, demonstrating that PP5 is not essential for survival. However, the Ppp5c-/- mice were underrepresented in offspring from heterozygous mating, indicating that PP5 provides some advantage during embryonic development. Mouse embryonic fibroblasts lacking PP5 showed increased susceptibility to UV light-induced stress, suggesting that PP5 may promote cell survival. PP5 deficiency in mice was also associated with reduced weight gain, lower fasting glycemia and improved glucose tolerance. However, the genetic disruption of PP5 did not alter insulin sensitivity or islet volume. Comparison of mitogen-activated protein kinase signaling in islets from Ppp5c-/- mice and MIN6 cells with reduced PP5 levels revealed that the lack of PP5 was associated with enhanced H2O2- and palmitate-induced JNK phosphorylation and apoptosis. This indicates that PP5 can suppress stress-induced apoptosis in β-cells by a mechanism involving the regulation of JNK phosphorylation and, thereby, contributing to a protective effect. PP5 suppression in MIN6 cells correlated with hypersecretion of insulin in response to glucose. When compared to wild-type littermate controls, Ppp5c-/- mice on a high-fat diet gained less weight. The mice lacking PP5 also had lower fasting glucose, which increased by high-fat diet feeding. A finding not observed in the Ppp5c+/+ mice. These observations may be explained, in part, by the enhanced serum insulin levels in the Ppp5c+/+ mice on the high-fat diet. Increased serum insulin was not observed in the Ppp5c-/- mice, which instead had lower levels of insulinemia after they were fed high-fat diet. High-fat diet feeding resulted in impaired glucose tolerance in both genotypes without an apparent difference in insulin sensitivity or β-cell function. These data indicate that the lack of PP5 protects mice against high-fat diet-induced weight gain but it cannot sustain glucose control during high-fat diet treatment. Together, our data provide evidence that PP5 is involved in the regulation of β- cell apoptosis and glucose homeostasis. PP5 may represent a double-edged sword in the fight against diabetes, since a PP5 inhibitor useful to prevent the progression towards obesity and diabetes, could possibly also harm the β-cells exposed to a glucolipotoxic environment

Diet supplementation with green tea extract epigallocatechin gallate prevents progression to glucose intolerance in db/db mice

<p>Abstract</p> <p>Background</p> <p>Green tea was suggested as a therapeutic agent for the treatment of diabetes more than 70 years ago, but the mechanisms behind its antidiabetic effect remains elusive. In this work, we address this issue by feeding a green tea extract (TEAVIGO™) with a high content of epigallocatechin gallate (EGCG) or the thiazolidinedione PPAR-γ agonist rosiglitazone, as positive control, to <it>db/db </it>mice, an animal model for diabetes.</p> <p>Methods</p> <p>Young (7 week-old) <it>db/db </it>mice were randomized and assigned to receive diets supplemented with or without EGCG or rosiglitazone for 10 weeks. Fasting blood glucose, body weight and food intake was measured along the treatment. Glucose and insulin levels were determined during an oral glucose tolerance test after 10 weeks of treatment. Pancreata were sampled at the end of the study for blinded histomorphometric analysis. Islets were isolated and their mRNA expression analyzed by quantitative RT-PCR.</p> <p>Results</p> <p>The results show that, in <it>db/db </it>mice, EGCG improves glucose tolerance and increases glucose-stimulated insulin secretion. EGCG supplementation reduces the number of pathologically changed islets of Langerhans, increases the number and the size of islets, and heightens pancreatic endocrine area. These effects occurred in parallel with a reduction in islet endoplasmic reticulum stress markers, possibly linked to the antioxidative capacity of EGCG.</p> <p>Conclusions</p> <p>This study shows that the green tea extract EGCG markedly preserves islet structure and enhances glucose tolerance in genetically diabetic mice. Dietary supplementation with EGCG could potentially contribute to nutritional strategies for the prevention and treatment of type 2 diabetes.</p

Calprotectin levels in amniotic fluid in relation to intra-amniotic inflammation and infection in women with preterm labor with intact membranes: A retrospective cohort study

Objective: To evaluate the concentrations of calprotectin in amniotic fluid with respect to intra-amniotic inflammation and infection and to assess the presence or absence of bacteria in the amnio-chorionic niche with respect to presence or absence of intra-amniotic inflammation. Study design: Seventy-nine women with singleton pregnancies and preterm labor with intact membranes (PTL) were included in the study. Amniotic fluid was collected at the time of admission by amniocentesis and calprotectin levels were analyzed from frozen/thawed samples using ELISA. Interleukin (IL)-6 concentration was measured by point-of-care test. Samples from amniotic fluid and the amnio-chorionic niche (space between amniotic and chorionic membranes) were microbiologically analyzed. Microbial invasion of the amniotic cavity (MIAC) was diagnosed based on a positive PCR result for Ureaplasma species, Mycoplasma hominis, 16S rRNA or positive culture. Intra-amniotic inflammation (IAI) was defined as amniotic fluid point-of-care IL-6 concentration ≥ 745 pg/mL. The cohort of included women was divided into 4 subgroups based on the presence or absence of IAI/MIAC; i) intra-amniotic infection, ii) sterile IAI, iii) intra-amniotic colonization and iv) neither MIAC nor IAI. Results: Women with intra-amniotic infection had a significantly higher intra-amniotic calprotectin concentration (median; 101.6 \ub5g/mL) compared with women with sterile IAI (median; 9.2 \ub5g/mL), women with intra-amniotic colonization (median; 2.6 \ub5g/mL) and women with neither MIAC nor IAI (median 4.6 \ub5g/mL) (p = 0.001). Moreover, significantly higher amniotic fluid calprotectin concentration was seen in women who delivered within 7 days (p = 0.003). A significant negative correlation was found between amniotic fluid calprotectin and gestational age at delivery (rho = 0.32, p = 0.003). Relatively more bacteria in the amnio-chorionic niche were found in the sterile IAI group compared with the other groups. Conclusions: Calprotectin concentrations in amniotic fluid were significantly higher in the intra-amniotic infection group compared with the other groups. Moreover, the bacterial presence in the amnio-chorionic niche was higher in IAI group

Glucagon-like peptide-1 receptor activation reduces ischaemic brain damage following stroke in Type 2 diabetic rats

Diabetes is a strong risk factor for premature and severe stroke. The GLP-1R (glucagon-like peptide-1 receptor) agonist Ex-4 (exendin-4) is a drug for the treatment of T2D (Type 2 diabetes) that may also have neuroprotective effects. The aim of the present study was to determine the efficacy of Ex-4 against stroke in diabetes by using a diabetic animal model, a drug administration paradigm and a dose that mimics a diabetic patient on Ex-4 therapy. Furthermore, we investigated inflammation and neurogenesis as potential cellular mechanisms underlying the Ex-4 efficacy. A total of seven 9-month-old Type 2 diabetic Goto–Kakizaki rats were treated peripherally for 4 weeks with Ex-4 at 0.1, 1 or 5 μg/kg of body weight before inducing stroke by transient middle cerebral artery occlusion and for 2–4 weeks thereafter. The severity of ischaemic damage was measured by evaluation of stroke volume and by stereological counting of neurons in the striatum and cortex. We also quantitatively evaluated stroke-induced inflammation, stem cell proliferation and neurogenesis. We show a profound anti-stroke efficacy of the clinical dose of Ex-4 in diabetic rats, an arrested microglia infiltration and an increase of stroke-induced neural stem cell proliferation and neuroblast formation, while stroke-induced neurogenesis was not affected by Ex-4. The results show a pronounced anti-stroke, neuroprotective and anti-inflammatory effect of peripheral and chronic Ex-4 treatment in middle-aged diabetic animals in a preclinical setting that has the potential to mimic the clinical treatment. Our results should provide strong impetus to further investigate GLP-1R agonists for their neuroprotective action in diabetes, and for their possible use as anti-stroke medication in non-diabetic conditions

"It's about meeting half way" : A qualitative study about how Kalmar municipality's team of specialists cooperate with assistant nurses

Dementia is one of the biggest global challenges within healthcare of our timeand to develop the interventions and preventions of this condition is important tobetter the quality of life for these individuals (Livington et al., 2017). In fall of 2018 the municipality of Kalmar established a team of specialists to assistassistant nurses in their care of the elders. The aim of this study is to understandhow a team of specialists cooperates with assistant nurses who work in dementiacare and if there are any differences in the view that the team has opposite to theassistant nurses. This study is based on semi-structured interviews with the teamof specialists and assistant nurses that works in residential homes with a focuson dementia and has had experiences from the team's work. The interviews arealso analyzed through the theoretical model cooperation theory. The studyindicates that there are several areas where the team of specialists has a positiveimpact in helping the assistant nurses. They provide education, both practicaland emotional support by giving advice and being a source where the assistantnurses can ventilate their concerns. They provide security for the workers whohave good attitudes towards the team in most areas of their work

"It's about meeting half way" : A qualitative study about how Kalmar municipality's team of specialists cooperate with assistant nurses

Dementia is one of the biggest global challenges within healthcare of our timeand to develop the interventions and preventions of this condition is important tobetter the quality of life for these individuals (Livington et al., 2017). In fall of 2018 the municipality of Kalmar established a team of specialists to assistassistant nurses in their care of the elders. The aim of this study is to understandhow a team of specialists cooperates with assistant nurses who work in dementiacare and if there are any differences in the view that the team has opposite to theassistant nurses. This study is based on semi-structured interviews with the teamof specialists and assistant nurses that works in residential homes with a focuson dementia and has had experiences from the team's work. The interviews arealso analyzed through the theoretical model cooperation theory. The studyindicates that there are several areas where the team of specialists has a positiveimpact in helping the assistant nurses. They provide education, both practicaland emotional support by giving advice and being a source where the assistantnurses can ventilate their concerns. They provide security for the workers whohave good attitudes towards the team in most areas of their work

Distribution of volunteers between ranges of fluid retention index (FRI).

<p>Values of 4 and higher are considered to indicate fluid retention consistent with dehydration.</p

(A) Relationship between the degree of albuminuria and the fluid retention index.

<p>Points at zero and below denote absence of albuminuria. Overlapping points may have been separated for clarity. Albuminuria is displayed as ln (1 + albumin/creatinine) to highlight the values close to zero. On this scale, micro-albuminuria corresponds to 0.667.</p

Scheme for calculating the fluid retention index (FRI), which is the mean of the FR scores for four urinary indexes of fluid retention.

<p>Scheme for calculating the fluid retention index (FRI), which is the mean of the FR scores for four urinary indexes of fluid retention.</p

Validation-based model selection for C-13 metabolic flux analysis with uncertain measurement errors

Accurate measurements of metabolic fluxes in living cells are central to metabolism research and metabolic engineering. The gold standard method is model-based metabolic flux analysis (MFA), where fluxes are estimated indirectly from mass isotopomer data with the use of a mathematical model of the metabolic network. A critical step in MFA is model selection: choosing what compartments, metabolites, and reactions to include in the metabolic network model. Model selection is often done informally during the modelling process, based on the same data that is used for model fitting (estimation data). This can lead to either overly complex models (overfitting) or too simple ones (underfitting), in both cases resulting in poor flux estimates. Here, we propose a method for model selection based on independent validation data. We demonstrate in simulation studies that this method consistently chooses the correct model in a way that is independent on errors in measurement uncertainty. This independence is beneficial, since estimating the true magnitude of these errors can be difficult. In contrast, commonly used model selection methods based on the chi(2)-test choose different model structures depending on the believed measurement uncertainty; this can lead to errors in flux estimates, especially when the magnitude of the error is substantially off. We present a new approach for quantification of prediction uncertainty of mass isotopomer distributions in other labelling experiments, to check for problems with too much or too little novelty in the validation data. Finally, in an isotope tracing study on human mammary epithelial cells, the validation-based model selection method identified pyruvate carboxylase as a key model component. Our results argue that validation-based model selection should be an integral part of MFA model development.Funding Agencies|Swedish Foundation for Strategic Research [FFL12-0220, IMT17-0245]; Swedish Research Council [2018-05418, 2018-03319]; Karolinska Institutet; CENIIT [15.09]; SciLifeLab National COVID-19 Research Program - Knut and Alice Wallenberg Foundation [2020.0182]; H2020 project PRECISE4Q grant [777107]; VINNOVA grants VisualSweden [2020-04711]; Swedish Fund for Research without Animal Experiments [F2019-0010]; ELLIIT [2020A12]</p