Exendin-4 differentially modulates essential functions of human dermal fibroblasts under normoglycemic and hyperglycemic conditions.

Evidence that exendin-4, a glucagon-like peptide-1 analog, might be used to treat poorly healing wounds under diabetic and nondiabetic conditions has gained increasing interest. Little is known, however, about the effects of the drug on the production by dermal fibroblasts of key extracellular matrix and regulatory compounds. Therefore, we used human skin fibroblasts cultured in normo- (1 g/l = 5.6 mmol/l glucose) or hyperglycemic (4.5 g/l = 25 mmol/l glucose) culture medium to test the effects of exendin-4 (0 - 100 nmol/l) on fibroblast functions crucial for the wound healing process. Exendin-4 increased the proliferative and metabolic activities, as measured by the BrdU (bromodeoxyuridine) and MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assays, respectively, of fibroblasts cultured in normoglycemic medium. Under hyperglycemic conditions, the drug had no effect on proliferation and reduced metabolic fibroblast activity. Exendin-4 decreased metalloproteinase-9 (MMP-9) secretion in the normoglycemic milieu only and increased tissue inhibitor of metalloproteinase-1 (TIMP-1) concentration in fibroblast colonies under both normo- and hyperglycemic experimental conditions. Exendin-4 increased the fibroblast growth factor-1 (FGF-1) concentration in cell colonies maintained in the normoglycemic milieu but decreased FGF-1 release when fibroblasts were grown in hyperglycemic medium. High glucose caused lactic dehydrogenase (LDH) leakage when compared with normoglycemic conditions, and exendin-4 was not able to prevent this effect, although it reduced LDH release from fibroblasts cultured in normoglycemic medium. Finally, exendin-4 increased glycosaminoglycan (GAG) content under both experimental conditions. Our results indicate that exendin-4 effects on the production of the extracellular matrix and regulatory proteins differ in human skin fibroblasts exposed to either normal or high glucose. In general, the beneficial effects of the drug, which may be important for the improvement of wound healing, are more pronounced under normoglycemic conditions, thus indicating that hyperglycemia attenuates the positive effects of exendin-4 on fibroblasts.

The phenotypic correlates and quantitative genetics of masculinization in the rodent, Octodon degus.

This corrects the article DOI: 10.1038/hdy.2017.20.

The phenotypic correlates and quantitative genetics of masculinization in the rodent, Octodon degus.

In some mammals, female characteristics have been shown to depend, in part, on the intrauterine position during development of female fetuses relative to male fetuses. Females developing in close proximity to males show behavioral, physiological and life history characteristics that are masculinized. With the exception of one inconclusive study, nothing is known of the genetic basis of this phenomenon. In this paper, we reported an analysis of the quantitative genetic basis of masculinization, as indicated by the anogenital distance (AGD) at birth and weaning, in the rodent Octodon degus. Because AGD is related to weight, we included a genetic analysis of pup weight at birth and weaning. Pairwise correlations showed that AGD at birth varied negatively with litter size and parturition number but positively with weaning AGD, birth weight, dam AGD and percentage of males in the litter. AGD at weaning varied similarly except that it tended to vary positively with litter size. Genetic (co)variances of AGD at birth and weight at birth differed in females and males. In females, the best genetic model included substantial effects of direct additive, additive maternal and a negative additive genetic covariance between these two. In males, variances were small and there was difficulty in discriminating between additive maternal and common environmental variances. By weaning, genetic (co)variances had somewhat declined in weight and were not statistically significant in AGD in either sex. This paper showed the occurrence of both phenotypic and genetic components in masculinization with effects being greater in females.

Colour ornamentation in the blue tit: quantitative genetic (co)variances across sexes.

Although secondary sexual traits are commonly more developed in males than females, in many animal species females also display elaborate ornaments or weaponry. Indirect selection on correlated traits in males and/or direct sexual or social selection in females are hypothesized to drive the evolution and maintenance of female ornaments. Yet, the relative roles of these evolutionary processes remain unidentified, because little is known about the genetic correlation that might exist between the ornaments of both sexes, and few estimates of sex-specific autosomal or sex-linked genetic variances are available. In this study, we used two wild blue tit populations with 9 years of measurements on two colour ornaments: one structurally based (blue crown) and one carotenoid based (yellow chest). We found significant autosomal heritability for the chromatic part of the structurally based colouration in both sexes, whereas carotenoid chroma was heritable only in males, and the achromatic part of both colour patches was mostly non heritable. Power limitations, which are probably common among most data sets collected so far in wild populations, prevented estimation of sex-linked genetic variance. Bivariate analyses revealed very strong cross-sex genetic correlations in all heritable traits, although the strength of these correlations was not related to the level of sexual dimorphism. In total, our results suggest that males and females share a majority of their genetic variation underlying colour ornamentation, and hence the evolution of these sex-specific traits may depend greatly on correlated responses to selection in the opposite sex.

Magnesium diboride coated bulk niobium: a new approach to higher acceleration gradient.

Bulk niobium Superconducting Radio-Frequency cavities are a leading accelerator technology. Their performance is limited by the cavity loss and maximum acceleration gradient, which are negatively affected by vortex penetration into the superconductor when the peak magnetic field at the cavity wall surface exceeds the vortex penetration field (Hvp). It has been proposed that coating the inner wall of an SRF cavity with superconducting thin films increases Hvp. In this work, we utilized Nb ellipsoid to simulate an inverse SRF cavity and investigate the effect of coating it with magnesium diboride layer on the vortex penetration field. A significant enhancement of Hvp was observed. At 2.8 K, Hvp increased from 2100 Oe for an uncoated Nb ellipsoid to 2700 Oe for a Nb ellipsoid coated with ~200 nm thick MgB2 thin film. This finding creates a new route towards achieving higher acceleration gradient in SRF cavity accelerator beyond the theoretical limit of bulk Nb.

The inhibitory effect of combination treatment with leptin and cannabinoid CB1 receptor agonist on food intake and body weight gain is mediated by serotonin 1B and 2C receptors.

Previous studies reported that the co-injection of leptin and cannabinoid CB1 receptor antagonists reduces food intake and body weight in rats, and this effect is more profound than that induced by these compounds individually. Additionally, serotonin mediates the effects of numerous anorectic drugs. To investigate whether serotonin interacts with leptin and endocannabinoids to affect food intake and body weight, we administered 5-hydroxytryptamine(HT)1B and 5-hydroxytryptamine(HT)2C serotonin receptor antagonists (3 mg/kg GR 127935 and 0.5 mg/kg SB 242084, respectively) to male Wistar rats treated simultaneously with leptin (100 µg/kg) and the CB1 receptor inverse agonist AM 251 (1 mg/kg) for 3 days. In accordance with previous findings, the co-injection of leptin and AM 251, but not the individual injection of each drug, resulted in a significant decrease in food intake and body weight gain. Blockade of the 5-HT1B and 5-HT2C receptors completely abolished the leptin- and AM 251-induced anorectic and body-weight-reducing effects. These results suggest that serotonin mediates the leptin- and AM 251-dependent regulation of feeding behavior in rats via the 5-HT1B and 5-HT2C receptors.

The effects of leptin in combination with a cannabinoid receptor 1 antagonist, AM 251, or cannabidiol on food intake and body weight in rats fed a high-fat or a free-choice high sugar diet.

High intake of fats and sugars has prompted a rapid growth in the number of obese individuals worldwide. To further investigate whether simultaneous pharmacological intervention in the leptin and cannabinoid system might change food and water intake, preferences for palatable foods, and body weight, we have examined the effects of concomitant intraperitoneal administration of leptin and AM 251, a cannabinoid 1 (CB1) receptor antagonist, or cannabidiol (CBD), a plant cannabinoid, in rats maintained on either a high-fat (HF) diet (45% energy from fat) or free-choice (FC) diet consisting of high-sucrose and normal rat chow (83% and 61% energy from carbohydrates, respectively). Leptin at a dose of 100 µg/kg injected individually for 3 subsequent days to rats fed a HF diet reduced significantly the daily caloric intake and inhibited body weight gain. The hormone had no significant effects, however, on either caloric intake, body weight or food preferences in rats fed an FC diet. Co-injection of leptin and 1 mg/kg AM 251 resulted in a further significant decrease in HF diet intake and a profound reduction in body weight gain both in HF diet- and FC diet-fed rats. This drug combination, however, had no effect on the consumption of high-sucrose chow. In contrast, 3mg/kg of CBD co-injected with leptin did not modify leptin effects on food intake in rats maintained on an FC or HF diet. None of the drug combinations affected water consumption. It is concluded that the concomitant treatment with leptin and AM 251 attenuated markedly body weight gain in rats maintained on high-calorie diets rich in fat and carbohydrates but did not affect preferences for sweet food.

Involvement of the monoaminergic system in the antidepressant-like activity of chromium chloride in the forced swim test.

Bio-metal chromium(III) is a crucial microelement for the proper functioning of living organisms. Previous preclinical and clinical studies reported its potential antidepressant properties. The aim of the present study was to examine the effect of antidepressants and noradrenergic and dopaminergic receptor antagonists on chromium chloride (CrCl3) activity in the forced swim test (FST) in mice and rats. Imipramine (5 mg/kg), fluoxetine (5 mg/kg) and reboxetine (5 mg/kg) but not bupropion (1 mg/kg), administered jointly with CrCl3 at a dose of 6 mg/kg, reduced the immobility time in the FST in mice. The reduction of the immobility time induced by the active dose (12 mg/kg) of CrCl3 was completely abolished by propranolol (2 mg/kg, ß-adrenoceptor antagonist), SCH 23390 (0.5 mg/kg, a dopamine D1 receptor antagonist), and partially by prazosin (1 mg/kg, an α1-adrenoceptor antagonist), yohimbine (1 mg/kg, an α2-adrenoceptor antagonist) and sulpiryd (50 mg/kg, a dopamine D2/D3 receptor antagonist) administration. The locomotor activity was significantly reduced by CrCl3 + reboxetine treatment, which did not influence the reboxetine enhancement of the antidepressant-like effect of CrCl3 in the FST. Moreover, CrCl3 at a dose of 32 mg/kg (although not at 12 mg/kg) significantly reduced the immobility and enhanced the climbing (but not swimming) time in the FST in rats, which indicates the involvement of the noradrenergic pathway in this effect. The present study indicates that the antidepressant-like activity of chromium in the FST is dependent (although to a different extent) on the noradrenergic, dopaminergic and serotonin systems.

Photochemical reactions involved in the phototoxicity of the anticonvulsant and antidepressant drug lamotrigine (Lamictal).

Lamotrigine (LTG) [3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine], an anticonvulsant and antidepressant drug Lamictal, produces a (photo)toxic response in some patients. LTG absorbs UV light, generating singlet oxygen (1O2) with a quantum yield of 0.22 in CH2Cl2, 0.11 in MeCN and 0.01 in D2O. A small production of superoxide radical anion was also detected in acetonitrile. Thus, LTG is a moderate photosensitizer producing phototoxicity and oxidizing linoleic acid. LTG is a weak 1O2 quencher (k(q) = 3.2 x 10(5) M(-1) s(-1) in MeCN), but its photodecomposition products in dimethyl sulfoxide (DMSO) quenched 1O2 very efficiently. Upon intense UV irradiation from a xenon lamp, LTG was photobleached rapidly in DMSO and slowly in acetonitrile, alcohol and water. The rate increased significantly when laser pulses at 266 nm were employed. The photobleaching products generated 1O2 twice as strongly as LTG. Photobleaching was usually accompanied by the release of chloride anions, which increased in the presence of ascorbic acid. This suggests the formation of aryl radicals via dechlorination, a process which may be responsible for the photoallergic response observed in some patients. Our results demonstrate that LTG is a moderate generator of 1O2 prone to photodechlorination, especially in a reducing environment, which can contribute to the reported phototoxicity of LTG.

Tumefactive cyst with a vascular blush as a late complication after combined embolization and stereotactic radiosurgery treatments for a cerebral arteriovenous malformation.

Cyst formation is a recognized late complication after stereotactic radiosurgery for cerebral arteriovenous malformations (AVMs). We report on a patient with delayed cyst formation after combined embolization and stereotactic radiosurgery treatments for a cerebral AVM. The true nature of the cyst was complicated by tumefactive magnetic resonance MR imaging characteristics. The tumefactive cyst was associated with an additional imaging finding suggestive of a neoplastic lesion - a 'blush' on conventional angiography.

Imaging characteristics of the subdural evacuating port system, a new bedside therapy for subacute/chronic subdural hematoma.

The Subdural Evacuating Port System is a new device intended to simplify the treatment of subacute/chronic subdural hematomas. The appearance of the winged canula positioned with its tip in the diploic space overlying the subdural space should allow the radiologist to identify it correctly. Its radiographic features are described here to help the radiologist comment on appropriate placement, and avoid mistaking it for a misplaced subdural drain.

Kinetics and mechanism of the reversible binding of nitric oxide to reduced cobalamin B(12r) (Cob(II)alamin).

The reduced form of aquacobalamin binds nitric oxide very effectively to yield a nitrosyl adduct, Cbl(II)-NO. UV-vis, (1)H-, (31)P-, and (15)N NMR data suggest that the reaction product under physiological conditions is a six-coordinate, "base-on" form of the vitamin with a weakly bound alpha-dimethylbenzimidazole base and a bent nitrosyl coordinated to cobalt at the beta-site of the corrin ring. The nitrosyl adduct can formally be described as Cbl(III)-NO-. The kinetics of the binding and dissociation reactions was investigated by laser flash photolysis and stopped-flow techniques, respectively. The activation parameters, DeltaH, DeltaS, and DeltaV, for the forward and reverse reactions were estimated from the effect of temperature and pressure on the kinetics of these reactions. For the "on" reaction of Cbl(II) with NO, the small positive DeltaS and DeltaV values suggest the operation of a dissociative interchange (I(d)) substitution mechanism at the Co(II) center. Detailed laser flash photolysis and (17)O NMR studies provide evidence for the formation of water-bound intermediates in the laser flash experiments and strongly support the proposed I(d) mechanism. The kinetics of the "off" reaction was studied using an NO-trapping technique. The respective activation parameters are also consistent with a dissociative interchange mechanism.

Inhibition of ATP-induced increase in muscarinic K+ current by trypsin, alkaline pH, and anions.

In atrial cells, the open probability of G protein-activated ACh-sensitive K+ (KACh) channels can be increased approximately fivefold by intracellular ATP (ATPi). Using inside-out patches, we examined how proteases, changes in intracellular pH, and different anions affect G protein-mediated activation and ATP-induced stimulation of the KACh channel. Treatment with trypsin (0.5 mg/ml) removed the GTP dependence of the KACh channel and abolished the ATP-induced stimulation. Intracellular GTP activated KACh channels at all intracellular pH values tested (6.0-8.0), with the concentration at which half-maximal activation (K1/2) occurred ranging from 0.3 (pH 8.0) to 6.7 (pH 6.0) microM. However, the ATPi-induced increase in KACh channel activity was inhibited at pH 8. 0 (K1/2 = pH 7.4). All anions tested except sulfate, phosphate, fluoride, and iodide supported GTP-induced activation. Of the anions that supported GTP-induced activation, only citrate blocked the ATP-induced stimulation of the KACh channel. These results indicate that the GTP- and ATP-mediated effects on the KACh channel use separate signaling pathways. The ATP-mediated effect involves a trypsin- and pH-sensitive mechanism.

Apo CIII gene transcription is regulated by a cytokine inducible NF-kappa B element.

Overproduction of Apo CIII causes elevated plasma triglyceride levels in transgenic animals and is associated with hypertriglyceridemia in humans. The regulation of apo CIII production is likely to play an important role in controlling plasma triglyceride levels. As an initial step in determining the role of transcriptional regulation in the production of apo CIII and in triglyceride metabolism, we have begun to characterize the activity of specific transcriptional regulatory elements in the CIII promoter. In the current study, we have identified and characterized an NF-kappa B regulatory element located 150 nucleotides upstream from the transcriptional start site of the apo CIII gene. Purified NF-kappa B, as well as an NF-kappa B protein in HepG2 cell nuclear extracts, bound specifically to this sequence element. The hepatic protein was induced by phorbol ester (PMA), and reacted with antibodies to the p50 and p65 subunits of NF-kappa B. The NF-kappa B element conferred PMA and IL1-beta inducible transcriptional activity to a heterologous promoter/reporter construct when transfected into HepG2 cells. Analysis of the full length CIII promoter demonstrated that the inducible activity of the NF-kappa B element was suppressed by sequences in the apo CIII enhancer element located approximately 500 nucleotides upstream of the NF-kappa B binding site. A deletion removing the enhancer restored the PMA inducible activity of the NF-kappa B binding site. These results indicate that apo CIII gene expression is regulated by NF-kappa B, and suggest that apo CIII production may be modulated by cellular signals, like inflammatory cytokines, that activate NF-kB.

Inhibition of carbonic anhydrase by parathyroid hormone and cyclic AMP in rat renal cortex in vitro.

It has been demonstrated that parathyroid hormone (PTH) inhibits the proximal tubular reabsorption of bicarbonate, and increases the urinary excretion of that ion. There is also a qualitative similarity between the alterations of the proximal tubular reabsorption of phosphate, sodium, and water after PTH administration and after acetazolamide administration. These findings suggest that the renal effect of PTH is possibly mediated through the inhibition of carbonic anhydrase in proximal tubules. Therefore, a possible inhibitory effect of PTH on carbonic anhydrase was evaluated in the homogenate of rat renal cortex by an indicator titration method. Incubation of cortical homogenates with PTH for 10 min at 37degreesC inhibited carbonic anhydrase activity. The inhibitory effect of PTH was ATP-, Mg++-, and K+-dependent and temperature-dependent; inactivation of PTH by heating at 100degreesC abolished the effect of PTH both to activate adenylate cyclase and to inhibit carbonic anhydrase. Calcium 5 mM also partially abolished effects of PTH to activate adenylate cyclase and to inhibit carbonic anhydrase. The inhibitory effect of PTH on carbonic anhydrase was specific to renal cortex. Cyclic AMP, the intracellular messenger substance for PTH, also inhibited carbonic anhydrase in renal cortex. The cyclic AMP-induced inhibition was also Mg++ dependent and temperature dependent, and required preincubation at 37degreesC. But 5'-AMP, a metabolic derivative of cyclic AMP without its biological effect, had no inhibitory effect on carbonic anhydrase. All the above results are consistent with the hypothesis that PTH inhibits proximal tubular reabsorption of bicarbonate and phosphate through the inhibition of carbonic anhydrase, and that inhibitory effect is mediated through the cyclic AMP system.