In vitro bioartificial skin culture model of tissue rejection and inflammatory/immune mechanisms

We hypothesized that an in vitro bioartificial skin rejection model using living LSEs grown in tissue culture could be developed for the study of autologous, allogenic, and/or xenogeneic inflammatory/immune mechanisms and topical immunosuppressive drugs. Human fibroblasts were mixed with type 1 rat-tail collagen to form a matrix (4 to 5 days), on which human keratinocytes were seeded. After a keratinocyte monolayer formed, CT cultures were raised to the air-liquid interface for continued growth. In the REJ LSE model, immunocytes isolated from human blood were seeded on top of the NHEK monolayer at the time of air-lifting. Thickness measurements of the acellular keratin and keratinocyte layers, and nuclear/cytoplasmic ratios, in both CT and REJ were made using digital image analysis. Immunostaining with anticytokeratin demonstrated a viable, keratin-producing epidermal layer; staining with anti-TGF-beta suggested a role for this cytokine in the rejection or wound-healing process. The LSE appeared histologically similar to normal human epidermis. Immunocytes added to the REJ cultures caused an obvious rejection response and were clearly identifiable in the gels as CD45+ staining cells. The LSE model appears promising for the study of immune/inflammatory mechanisms, thermal injury, screening antirejection agents that might be applied topically and as an in vitro replacement for skin graft studies in animals.     

Learning navigational maps through potentiation and modulation of hippocampal place cells

We analyze a model of navigational map formation based on correlation-based, temporally asymmetric potentiation and depression of synapses between hippocampal place cells. We show that synaptic modification during random exploration of an environment shifts the location encoded by place cell activity in such a way that it indicates the direction from any location to a fixed target avoiding walls and other obstacles. Multiple maps to different targets can be simultaneously stored if we introduce target-dependent modulation of place cell activity. Once maps to a number of target locations in a given environment have been stored, novel maps to previously unknown target locations are automatically constructed by interpolation between existing maps.     

Increased myogenic tone and diminished responsiveness to ATP-sensitive K+ channel openers in cerebral arteries from diabetic rats

Diabetes mellitus has profound adverse effects on vascular and, in particular, endothelial function. Although pressure-induced constriction ("myogenic tone") is a major contributor to the regulation of blood flow, little is known about the effects of diabetes on this response. Diabetes has been shown to diminish the dilation of cerebral arteries to synthetic ATP-sensitive K+ (KATP) channel openers. In this study, we explored the effects of diabetes induced in rats by streptozotocin on cerebral artery (250 to 300 microns) myogenic tone and on vasodilations to the synthetic KATP channel openers pinacidil and levcromakalim. Elevation of intravascular pressure caused a graded membrane potential depolarization and constriction, which was greater in arteries from diabetic rats compared with normal rats (at 60 mm Hg, 5 mV more depolarized and 22 microns more constricted). Pressurized arteries (at 60 mm Hg) from diabetic rats were 5- to 15-fold less sensitive to pinacidil and levcromakalim than were control arteries (EC50 values for pinacidil and levcromakalim were 1.4 and 0.6 mumol/L, respectively, in diabetic animals and 0.3 and 0.04, respectively, in control animals; P < .05). Removal of the endothelium or addition of a NO synthase inhibitor, NG-nitro-L-arginine (LNNA), in control arteries decreased the sensitivity to KATP channel openers and depolarized and constricted control arteries to levels similar to those observed in arteries from diabetic animals. Sodium nitroprusside caused a membrane potential hyperpolarization and enhanced the response to pinacidil in arteries from diabetic animals. Removal of the endothelium or LNNA had little effect on the apparent KATP channel opener sensitivity, the membrane potential, and pressure-induced constrictions of arteries from diabetic animals. The results are consistent with the hypothesis that this type of diabetes leads to a decrease in tonic NO release from the endothelium, which in turn causes membrane potential depolarization and vasoconstriction, resulting in a diminished response to KATP channel openers.     

Urocortin 1 and 3 Impair Maternal Defense Behavior in Mice.

Lactating female mice fiercely defend offspring while exhibiting decreased fear and anxiety. Recent work (J. S. Lonstein & S. C. Gammie, 2002) found that intracerebroventricular (icv) injections of corticotropin releasing factor (CRF), a putative anxiogenic peptide, inhibit maternal defense behavior. This study examines effects of CRF-related peptides, urocortin (Ucn) 1 and Ucn 3, on maternal aggression in mice. Intracerebroventricular injections of both Ucn 1 (0.2 μg) and Ucn 3 (0.5 μg) reduced aggression but not pup retrieval. c-Fos levels were elevated by intracerebroventricular injections of Ucn 1 (0.2 μg) and Ucn 3 (0.5 μg) in 2 and 6 brain regions, respectively; however, both triggered increases in bed nucleus of the stria terminalis dorsal (BNSTd) and lateral septum (LS). These findings suggest that CRF-related peptides similarly modulate maternal aggression and that BNSTd/LS may be critical sites for negative regulation of maternal aggression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Executive Self, Self-Esteem, and Negative Affectivity: Relations at the Phenotypic and Genotypic Level.

Complementary approaches examined the relations among executive self, self-esteem, and negative affectivity. A cross-sectional (N = 4,242) and a longitudinal (N = 158) study established that self-esteem mediated the relation between executive self and negative affectivity. A 3rd study (N = 878 twin pairs) replicated this pattern and examined genetic and environmental influences underlying all 3 phenotypes. Covariation among the 3 phenotypes reflected largely common genetic influences, although unique genetic effects explained variability in both executive self and negative affectivity. Executive self was influenced by shared environmental influences unique from those affecting self-esteem and negative affectivity. Nonshared environmental influences accounted for the majority of variance in each construct and were primarily unique to each. The unique genetic and nonshared environmental influences support the proposition that the executive self, self-esteem, and negative affectivity capture distinct and important differences between people. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Validation of the in vivo intravascular ultrasound measurement of in-stent neointimal hyperplasia volumes

OBJECTIVES: This study was undertaken to validate the in vivo intravascular ultrasound (IVUS) measurement of in-stent neointimal hyperplasia (IH) volumes. BACKGROUND: Because stents reduce restenosis compared to balloon angioplasty, stent use has increased significantly. As a result, in-stent restenosis is now an important clinical problem. Serial IVUS studies have shown that in-stent restenosis is secondary to intimal hyperplasia. To evaluate strategies to reduce in-stent restenosis, accurate measurement of in-stent neointimal tissue is important. METHODS: Using a porcine coronary artery model of in-stent restenosis, single Palmaz-Schatz stents were implanted into 16 animals with a stent:artery ratio of 1.3:1. Intravascular ultrasound imaging was performed at 1 month, immediately prior to animal sacrifice. In vivo IVUS and ex vivo histomorphometric measurements included stent, lumen and IH areas; IH volumes were calculated with Simpson's rule. RESULTS: Intravascular ultrasound measurements of IH (30.4+/-11.0 mm3) volumes correlated strongly with histomorphometric measurements (26.7+/-8.5 mm3, r=0.965, p < 0.0001). The difference between the IVUS and the histomorphometric measurements of IVUS volume was 4.1+/-2.7 mm3 or 15.8+/-11% (standard error of the estimate=0.7). Both histomorphometry and IVUS showed that IH was concentric and uniformly distributed over the length of the stent. Intravascular ultrasound detected neointimal thickening of < or =0.2 mm in 5 of 16 stents. Sample size calculations based on the IVUS measurement of IH volumes showed that 12 stented lesions/arm would be required to show a 50% reduction in IVUS-measured IH volume and 44 stented lesions/arm would be required to show a 25% reduction in IH volume. CONCLUSION: In vivo IVUS measurement of IH volumes correlated strongly with ex vivo histomorphometry. Using volumetric IVUS end points, small sample sizes should be necessary to demonstrate effectiveness of strategies to reduce in-stent restenosis.     

Quality of life and dementia

OBJECTIVE: To review the relationship between quality of life (QOL) and dementia. Development. QOL is a factor which takes into account all the different aspects of life which make a person feel that life is worth living, such as: 1. Physical health. 2. Functional status. 3. Psychological and cognitive sphere, and 4. Social health. There are two types of instruments for evaluating these aspects: firstly general ones which measure the QOL independently of illness, and secondly those which are specific to the illness concerned. In dementia, QOL covers the same traditional areas: cognitive competence, capacity to carry out everyday activities, social conduct and the balance between positive and negative emotions. However, evaluation of QOL in dementia has its own specific difficulties, since it is often impossible to determine such a fundamental factor as the subjective well-being of the patient, in which case the opinion of the person looking after the patient is essential. According to Lawton's approximation, as well as the subjective aspect of perceived psychic welfare and quality of life, the QOL in dementia is composed of external social and objective dimensions such as behaviorally competence and the quality of the patient's environment. In a review done in 1995 it was found that most of the instruments designed to measure the QOL have not been sufficiently validated for Alzheimer's disease. CONCLUSIONS: QOL in dementia has specific features including external aspects such as the opinion of the carer and the quality of the patient's environment in addition to the subjective aspects. It is necessary to develop and validate specific instruments for QOL in dementia.     

Hypoxia stimulates insulin-like growth factor binding protein 1 (IGFBP-1) gene expression in HepG2 cells: a possible model for IGFBP-1 expression in fetal hypoxia

IGFBP-1 is elevated in fetuses with long-term, chronic hypoxia and intrauterine growth restriction. We investigated the hypothesis that hypoxia regulates IGFBP-1 in the human fetus in vivo and IGFBP-1 gene expression and protein in vitro. Umbilical artery IGFBP-1 levels (mean +/- SEM) from term babies with respiratory acidosis (acute hypoxia), normal babies, and those with mixed respiratory/metabolic acidosis (more profound and prolonged hypoxia) were measured using an immunoradiometric assay. IGFBP-1 levels were similar in normal (n = 12) and acutely hypoxic (n = 6) babies (189.1 +/- 71.8 vs. 175.8 +/- 45.9 ng /ml, respectively, P = 0.789). However, with more profound and prolonged hypoxia (n = 19), IGFBP-1 levels were markedly elevated (470.6 +/- 80.0 ng /ml, P = 0.044). To investigate IGFBP-1 regulation by hypoxia in vitro, HepG2 cells were incubated under hypoxia (pO2 = 2%) and normoxia (pO2 = 20%). IGFBP-1 protein and mRNA increased 8- and 12-fold, respectively, under hypoxic conditions. Hypoxia did not affect protein or mRNA levels of IGFBP-2 or -4. IGFBP-5 and -6 mRNAs, undetectable in control cells, were not induced by hypoxia, whereas minimally expressed IGFBP-3 mRNA increased twofold. Investigation into IGFBP-1 gene structure revealed three potential consensus sequences for the hypoxia response element (HRE) in the first intron. To investigate functionality, a 372-bp fragment of IGFBP-1 intron 1, containing putative HREs, was placed 5' to a heterologous hsp70 promoter in a plasmid using luciferase as a reporter gene. Under hypoxia, reporter gene activity increased up to 30-fold. Mutations in the middle HRE abolished reporter activity in response to hypoxia, suggesting that this HRE is functional in the IGFBP-1 hypoxia response. Cotransfection of HRE reporter genes with a constitutively expressing hypoxia-inducible factor 1 plasmid in HepG2 cells resulted in a fourfold induction of reporter activity, suggesting a role for hypoxia-inducible factor 1 in hypoxia induction of IGFBP-1 gene expression. These data support the hypothesis that hypoxia regulation of IGFBP-1 may be a mechanism operating in the human fetus to restrict insulin-like growth factor-mediated growth in utero under conditions of chronic hypoxia and limited substrate availability.     

Action of bleomycin on structural mimics of intermediates in DNA double-strand cleavage

Bleomycin-induced cleavage was examined in several nicked, gapped, or intact duplex DNA substrates, including a structure designed to mimic a proposed singly nicked intermediate in double-strand cleavage. This nicked structure appeared to correctly target the second cleavage event in the complementary strand, resulting in a blunt-ended double-strand break, similar to that induced directly by bleomycin alone in an intact duplex of the same sequence. A one-base-gapped structure was markedly less efficient in correctly targeting bleomycin attack in the complementary strand. The results are consistent with a model of bleomycin-induced double-strand cleavage in which the nick formed by the initial bleomycin attack serves to target secondary attack to a specific position in the complementary strand, resulting in a double-strand break with a defined geometry.