Vimentin intermediate filaments modulate cell traction force but not cell sensitivity to substrate stiffness

The ability of cells to sense and respond to the mechanical stiffness of the surrounding matrix is important to support normal cell function, wound healing, and development. Central to the process of durosensing is the cytoskeleton composed of three classes of filaments: F-actin, microtubules, and intermediate filaments (IFs). Vimentin is an IF protein that contributes significantly to cell mechanics and cell traction force, which is required to probe extracellular matrix. The role of vimentin in how cells sense and respond to the mechanical rigidity of extracellular matrix is largely unclear. To investigate the role of vimentin in durosensing, we knocked down the vimentin expression level in 3T3 fibroblasts using shRNA transfection and measured cellular responses as functions of substrate stiffness. We quantified durosensitivity by the rates at which cell area and traction force change with substrate stiffness. Our results show that that vimentin plays a role in durosensing by modulating traction force and knocking out vimentin did not significantly affect durosensitivity. These results indicate that vimentin may be a redundant component of the machinery that cells use to sense substrate stiffness.

High molecular weight FGF2 isoforms demonstrate canonical receptor-mediated activity and support human embryonic stem cell self-renewal

Basic fibroblast growth factor (FGF2) is a highly pleiotropic member of a large family of growth factors with a broad range of activities, including mitogenesis and angiogenesis (Ornitz et al., 1996; Zhang et al., 2006), and it is known to be essential for maintenance of balance between survival, proliferation, and self-renewal in human pluripotent stem cells (Eiselleova et al., 2009; Zoumaro-Djayoon et al., 2011). A single FGF2 transcript can be translated into five FGF2 protein isoforms, an 18kDa low molecular weight (LMW) isoform and four larger high molecular weight (HMW) isoforms (Arese et al., 1999; Arnaud et al., 1999). As they are not generally secreted, high molecular weight (HMW) FGF2 isoforms have predominantly been investigated intracellularly; only a very limited number of studies have investigated their activity as extracellular factors. Here we report over-expression, isolation, and biological activity of all recombinant human FGF2 isoforms. We show that HMW FGF2 isoforms can support self-renewal of human embryonic stem cells (hESCs) in vitro. Exogenous supplementation with HMW FGF2 isoforms also activates the canonical FGFR/MAPK pathway and induces mitogenic activity in a manner similar to that of the 18kDa FGF2 isoform. Though all HMW isoforms, when supplemented exogenously, are able to recapitulate LMW FGF2 activity to some degree, it appears that certain isoforms tend to do so more poorly, demonstrating a lesser functional response by several measures. A better understanding of isoform-specific FGF2 effects will lead to a better understanding of developmental and pathological FGF2 signaling.

FGF2 Overrides TGFβ1-Driven Integrin ITGA11 Expression in Human Dermal Fibroblasts

Deposition of collagen-based extracellular matrix by fibroblasts during wound healing leads to scar formation--a typical outcome of the healing process in soft tissue wounds. The process can, however, be skewed in favor of tissue regeneration by manipulation of wound environment. Low oxygen conditions and supplementation with FGF2 provide extracellular cues that drive wound fibroblasts towards a pro-regenerative phenotype. Under these conditions, fibroblasts dramatically alter expression of many genes among which the most significantly deregulated are extracellular matrix and adhesion molecules. Here we investigate the mechanism of a collagen I binding integrin α11 (ITGA11) deregulation in response to low oxygen-mediated FGF2 effects in dermal fibroblasts. Using RT-PCR, qRT-PCR, Western blotting, and immunocytochemistry, we describe significant down-regulation of ITGA11. Decrease in ITGA11 is associated with its loss from focal adhesions. We show that loss of ITGA11 requires FGF2 induced ERK1/2 activity and in the presence of FGF2, ITGA11 expression cannot be rescued by TGFβ1, a potent activator of ITGA11. Our results indicate that FGF2 may be redirecting fibroblasts towards an anti-fibrotic phenotype by overriding TGFβ1 mediated ITGA11 expression.

Expression and differentiation between OCT4A and its Pseudogenes in human ESCs and differentiated adult somatic cells

The POU5F1 gene codes for the OCT4 transcription factor, which is one of the key regulators of pluripotency. Its transcription, alternative splicing, and alternative translation leading to the synthesis of the active, nuclear localized OCT4A has been described in detail. Much less, however, is known about actively transcribed OCT4 pseudogenes, several of which display high homology to OCT4A and can be expressed and translated into proteins. Using RT-PCR followed by pseudogene-specific restriction digestion, cloning, and sequencing we discriminate between OCT4A and transcripts for pseudogenes 1, 3 and 4. We show that expression of OCT4 and its pseudogenes follows a developmentally-regulated pattern in differentiating hESCs, indicating a tight regulatory relationship between them. We further demonstrate that differentiated human cells from a variety of tissues express exclusively pseudogenes. Expression of OCT4A can, however be triggered in adult differentiated cells by oxygen and FGF2-dependent mechanisms.

Mutagenicity (micronucleus test in Vicia faba root tips), polycyclic aromatic hydrocarbons and heavy metal content of sediments collected in Tiber river and its tributaries within the urban area of Rome

Sediments collected in Tiber river and in its main tributary water courses within the urban area of Rome were tested for mutagenicity by means of Vicia faba root tips micronucleus (MN) test. Representative samples were scored for micronucleus generating events (chromosome/chromatid loss and fragments) too. Sediments were assayed for content of the thirteen most important chemicals of polycyclic aromatic hydrocarbon (PAH) group and for some heavy metal ions (Cd, Cr, Cu, Ni, Pb, Zn). Samples were collected in four tributary rivers (Prima Porta, Acqua Traversa, Aniene and Magliana) just before their confluence with Tiber river and at different stations along the Tiber river itself upstream and downstream the sites of confluence of the sampled tributaries. All samples were collected in July 1992. An alarming level of mutagenicity was reached in most of the tested stations, with an effect comparable to an X-rays exposure up to 0.4 Gy. Chemical analysis showed that the total amount of identified PAHs ranged from 4.5 to 625.2 ng/g of dry matrix in the different stations and the total amount of heavy metals ranged from 130 to 570 ppm. Tiber mutagenicity is likely to be mainly due to local factors such as the confluence of a small polluted tributary rather than to large scale effect due to an upstream-downstream relationship.

Determination of plasma alpha-glutathione-S-transferases in chronic alcohol abusers: relationship with alcohol intake and liver involvement

Alpha-gluthathione-S-transferases (alpha-GSTs) are enzymes involved in the cellular detoxifying processes; elevated circulating alpha-GSTs activity is considered to be an early index of liver damage. Glutathione (GSH) is the substrate for alpha-GST action.

THE AIMS OF OUR STUDY WERE

(1) to evaluate plasma GSH levels and alpha-GST activity in chronic alcohol abusers with or without liver cirrhosis; (2) to define the relationship between these two biochemical parameters; (3) to establish their clinical relevance in patients with alcohol abuse and/or liver damage. We studied 69 subjects (18 healthy subjects and 51 chronic alcohol abusers: 29 without liver cirrhosis and 22 with). Plasma alpha-GST activity was determined on baseline samples and every following day for a total of 10 days in five alcoholics by HEPKIT (Alpha-Biotech, Biotrin International, Dublin, Ireland). GSH was determined on all subjects' baseline samples by fluorescent high-performance liquid chromatography. Alcohol intake was evaluated in all patients by determining blood-alcohol concentrations. Significant increases in plasma alpha-GSTs were observed in 9/29 (31%) alcoholics and 3/22 (13.6%) cirrhotics irrespective of their alcohol intake. GSH was significantly lower than normal values (P < 0.001) in all alcoholics with or without cirrhosis (controls 10.4 +/- 4.8; alcoholics without cirrhosis 3.9 +/- 1.4; alcoholics with cirrhosis 3.3 +/- 1.6). No correlation was observed between plasma alpha-GST and GSH levels. Our data indicate that: (1) alpha-GST activity does not correlate with GSH levels in the plasma; (2) alpha-GSTs do not have clinical relevance as markers of recent alcohol intake; (3) in cirrhotics, alpha-GST does not provide more information than other liver function tests. However, plasma alpha-GST determination may be useful in selecting a subgroup of alcoholics in whom routine biochemical markers of liver damage are within reference ranges.

Free radicals and not acetaldehyde influence the circulating levels of glutathione after acute or chronic alcohol abuse: in vivo and in vitro studies

BACKGROUND

The oxidation of ethanol and acetaldehyde enhances the production of various free radicals involved in membrane lipoperoxidation, and decreases glutathione levels.

AIMS

We evaluated the effects of acute and chronic ethanol use in vivo, with or without the administration of S-adenosyl-methionine (SAME, 2 g I.v.), and the effects of ethanol and acetaldehyde in vitro, on the erythrocyte levels of malonyldialdehyde and glutathione, and of its principal synthesizing enzymes, gamma-glutamyl-cysteine-synthetase and glutathione-synthetase.

METHODS

Twelve healthy volunteers (age range 26-44 years, median 32 years) and 20 chronic alcohol abusers without liver disease (age range 26-57 years, median 44 years) were studied. Malonyldialdehyde was evaluated by thiobarbituric acid; glutathione and its enzymes by high performance liquid chromatography using a fluorescent detector.

RESULTS

In the healthy subjects, an acute load of ethanol induced a significant decrease in plasma levels of glutathione, which was inhibited by the infusion of S-adenosyl-methionine. In the erythrocytes of alcoholic patients, glutathione and glutathione-synthetase were decreased while malonyldialdehyde was increased. In vitro, acetaldehyde did not affect either the glutathione or the glutathione-related enzyme levels.

CONCLUSIONS

Our data suggest that the alterations in glutathione metabolism in the erythrocytes of alcoholics may be due principally to the production of free radicals, as supported by the high levels of malonyldialdehyde observed.

Effect of S-adenosyl-L-methionine administration on red blood cell cysteine and glutathione levels in alcoholic patients with and without liver disease

We measured glutathione and cysteine concentrations in erythrocytes of chronic alcohol misusers with (20 subjects) and without liver cirrhosis (20 subjects). Glutathione levels were decreased, whereas those of cysteine were increased in all patients. Parenteral treatment with S-adenosylmethionine (SAME); (2 g daily in 250 ml 0.15 M NaCl for 15 days) corrected the erythrocyte thiol alterations. We conclude that parenteral treatment with SAME affects the metabolism of SH compounds in erythrocytes of alcoholic patients.

Regional variations in total and nonprotein sulfhydryl compounds in the human gastric mucosa and effects of ethanol

This study evaluated the regional distribution of sulfhydryl compounds in the human gastric mucosa and the effect of ethanol on gastric sulfhydryl tissue levels. Total sulfhydryl, glutathione, and cysteine and their oxidized forms were measured in biopsy specimens taken from the gastric body and antrum of 22 healthy volunteers. Total sulfhydryl and glutathione contents of the body of the stomach were significantly higher than those of the antrum. In contrast, cysteine concentration was higher in the gastric antrum than in the body. No difference was found in the levels of oxidized sulfhydryls between the gastric body and antrum. The effect of acute administration of ethanol on gastric sulfhydryl content was studied in nine subjects. Ethanol caused gross mucosal damage and lowered the concentration of sulfhydryl compounds in both the body and the antrum. In 10 chronic alcoholics total sulfhydryl and glutathione, but not cysteine, were markedly decreased in the gastric body but not in the antrum as compared with nonalcoholic controls. In conclusion, 1) the human gastric body contains significantly higher tissue levels of total sulfhydryls and glutathione and lower concentrations of cysteine than the antrum; 2) ethanol in a damaging concentration significantly decreases gastric tissue levels of sulfhydryl compounds; and 3) chronic ethanol intake lowers total sulfhydryl and glutathione tissue levels in the gastric body.

[Hypomagnesemia and hypokalemia as risk factors of arrhythmia in acute phase myocardial infarction]

In a uniform group of 30 patients the A. have assessed the incidence of lower serum K+ and Mg++ concentrations on the probability of arrhythmias onset in the acute phase of myocardial infarction. The study shows that lower K+ and Mg++ levels significantly influence only the onset of ventricular tachycardia and monofocal PVC.

[Cadmium in the total diet of the typical Italian collective]

An inquiry, by the "Duplicate Portion" technique, has been made to estimate the daily assimilation of cadmium in various collectivities of Rome, representative of different economical-social and sanitary realities. At this regard, 132 complete meals, coming from a hospital canteen, a nursing home for old people, a big company, a community of students and an agricultural firm, have been examined. The sample has been mineralized to white ashes and analyzed in spectrophotometry at A.A. with a little oven of graphite. The data about cadmium assimilation, that we have obtained, are included between 12 and 25 micrograms/day and they are placed at medium-low levels, if we compare then with an assimilation of 15-60 micrograms/day, carried from studies on various populations. No daily data exceeded the limit of tolerability of 57-71 micrograms/day suggested from the W.H.O. Our data, coming the point, do not indicate a particular situation of danger for the groups of population we have studied.

Increased GH responsiveness to dopamine receptor stimulation in alcohol addicts during the late withdrawal syndrome

In humans the release of growth hormone (GH) elicited by dopamine (DA) and DA agonists may represent a reliable model to assess change in sensitivity of DA receptors. We now report that in chronic alcoholics, 4-7 days after the suspension of alcohol consumption, the increase of GH response to DA infusion was higher than that seen in non alcoholic volunteers. The specificity of this GH response to DA administration was demonstrated by the use of domperidone, a novel peripheral antagonist of DA receptors. These results suggest the development of hyper-responsiveness of DA receptors involved in the control of GH secretion in chronic alcoholics during the later phases of the "withdrawal syndrome".

Drug induction and experimental cholestasis

The occlusion of bile duct reduced the microsomal cytochrome P-450 activity in the liver of rats. However, the effects of the inducer drug, phenobarbital, were not abolished.

Preliminary results on the use of Tenax for the extraction of pesticides and polynuclear aromatic hydrocarbons from surface and drinking waters for analytical purposes

The use of Tenax GC for the extraction of organic micro-pollutants such as pesticides and polynuclear aromatic hydrocarbons from water has been studied. In the absence of other contaminants and under conditions standardized at the time as optimal, the recovery of such substances is, on average, over 90%, both for the organochlorine and organophosphorus pesticides and for polynuclear aromatic hydrocarbons. Research into the effectiveness of extraction with Tenax from natural waters and water artificially contaminated with surfactants, fats and oils etc., in the laboratory is now being carried out.