Reversible changes in goldfish brain polyamine concentrations and synthetic enzymes after cold exposure

Exposure of goldfish to the cold (5 degrees C) caused a sharp increase in brain putrescine level during the first week. Such increase continued at a minor rate for the whole period of exposure (2 months). In contrast, the content of spermidine and spermine remained unchanged. Putrescine increase was concomitant with a remarkable rise in ornithine decarboxylase activity (ODC), which reached a maximum stimulation after 1 week of cold exposure, and declined thereafter, remaining significantly higher than the control for the entire period of study. Cold exposure caused also a reduction of S-adenosylmethionine decarboxylase (AdoMetDC) activity and an increase of ornithine level, whereas methionine content was unchanged. When fish exposed to cold temperature were returned to 20 degrees C, the modifications observed on brain polyamine metabolism were completely reversed. Supported by previous observations, our results suggest that the changes in the polyamine metabolism induced in goldfish brain by cold exposure could represent an homeostatic mechanism carried out by the goldfish to minimize the possible effects of thermal changes.

Studies on human neutrophil biological functions by means of formyl-peptide receptor agonists and antagonists

Phagocytes are activated by several extracellular signals, including formyl-peptides derived from bacterial proteins or disrupted cells. The most intensely studied member of the formylpeptide family is the synthetic tripeptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), whose specific receptors have been identified on neutrophil plasma membrane and subsequently cloned. The fMLP-receptor interaction activates multiple transduction pathways responsible for various neutrophil functions such as adhesion, chemotaxis, exocytosis of secretory granules and superoxide anion production, which represent the physiological response to bacterial infection and tissue damage. An unresolved question is whether signaling requirements are identical or specific for each physiological function. The development of fMLP receptor agonists and antagonists has led to an improvement of our knowledge about the above issue. Of particular interest is the possibility that receptorial antagonists, able to transiently inhibit neutrophil responses to formylpeptides, could be therapeutic agents in the treatment of inflammation-related diseases. Aim of this review is, i) to summarise the current understanding of the series of events that begins at the level of formylpeptide-receptor interaction and is responsible for the activation of transduction pathways, which finally determine neutrophil response; ii) to define the state of art regarding the synthesis as well as the biological actions of fMLP receptor agonists and antagonists.

Detection of early ischemia in severe head injury by means of arteriovenous lactate differences and jugular bulb oxygen saturation. Relationship with CPP, severity indexes and outcome. Preliminary analysis

Early ischemia may be highly relevant in patients with severe head injuries. The aims of the study were: 1) to define if abnormal arteriovenous lactate difference (AVDL) and jugular bulb oxygen saturation (SjO2) are found in the early 24 hrs post injury; 2) to compare if abnormalities of SjO2 and of AVDL were associated with a specific typology of severity indexes and outcome; 3) to detect any association between abnormal AVDL and SjO2 with levels of cerebral perfusion pressure (CPP). The study involved 29 patients, with CPP, AVDL and SjO2 measured within 24 hours post-injury.

RESULTS

1) Abnormal AVDL was found in 21% while abnormal SjO2 was detected in 38% of the patients; 2) abnormal AVDL was associated with cases of most severe injury; 3) CPP level below 60 mmHg was associated with abnormal AVDL and SjO2. Low CPP appeared to be the most likely measurable cause of early ischemia. Abnormalities of AVDL appeared to be more sensitive, than SjO2, with regard to detection of the most severe cases.

Noninvasive molecular tracking of colonizing wolf (Canis lupus) packs in the western Italian Alps

We used noninvasive methods to obtain genetic and demographic data on the wolf packs (Canis lupus), which are now recolonizing the Alps, a century after their eradication. DNA samples, extracted from presumed wolf scats collected in the western Italian Alps (Piemonte), were genotyped to determine species and sex by sequencing parts of the mitochondrial DNA (mtDNA) control-region and ZFX/ZFY genes. Individual genotypes were identified by multilocus microsatellite analyses using a multiple tubes polymerase chain reaction (PCR). The performance of the laboratory protocols was affected by the age of samples. The quality of excremental DNA extracts was higher in samples freshly collected on snow in winter than in samples that were older or collected during summer. Preliminary mtDNA screening of all samples allowed species identification and was a good predictor of further PCR performances. Wolf, and not prey, DNA targets were preferentially amplified. Allelic dropout occurred more frequently than false alleles, but the probability of false homozygote determinations was always < 0.001. A panel of six to nine microsatellites would allow identification of individual wolf genotypes, also whether related, with a probability of identity of < 0.015. Genealogical relationships among individuals could be determined reliably if the number of candidate parents was 6-8, and most of them had been sampled and correctly genotyped. Genetic data indicate that colonizing Alpine wolves originate exclusively from the Italian source population and retain a high proportion of its genetic diversity. Spatial and temporal locations of individual genotypes, and kinship analyses, suggest that two distinct packs of closely related wolves, plus some unrelated individuals, ranged in the study areas. This is in agreement with field observations.

Inhibition of neutrophil responses by cyclosporin A. An insight into molecular mechanisms

OBJECTIVE

Cyclosporin A (CsA) is an effective agent in rheumatoid arthritis (RA), slowing joint damage progression. Its therapeutic effect on T lymphocytes has been studied extensively, but there is little information available about neutrophils, the cells responsible for a substantial proportion of inflammation. A study was performed to investigate the in vitro effects of CsA on neutrophil functions triggered by several agonists and determine whether the drug could counteract the binding of formyl-methionyl-leucyl-phenylalanine (fMLP) to its receptor and/or modulate changes in the intracellular Ca(2+) concentration ([Ca(2+)]i).

METHODS

CsA was added to neutrophils 5-50 min before the incubation steps for neutrophil function assays (chemotaxis, superoxide anion production, lysozyme release), calcium measurements and receptor binding experiments.

RESULTS

CsA appeared to be particularly effective in lowering chemotaxis, superoxide anion production and lysozyme release induced by different agonists. However, it did not significantly affect either basal or agonist-stimulated neutrophil [Ca(2+)]i and the interaction between fMLP and its receptor.

CONCLUSIONS

Because of its in vitro inhibition of neutrophil functions, CsA appears to have considerable potential as an anti-inflammatory drug. Moreover, as it is also a potent immunosuppressive agent, it may reduce the progression of joint damage in RA. More work remains to be done to clarify the molecular mechanism of CsA action on neutrophils.

Characterization of [3H]CGP 12177 binding to beta-adrenergic receptors in intact eel hepatocytes

The aim of this study was to characterize [3H]CGP 12177 (CGP) binding to beta-adrenergic receptors in isolated hepatocytes of the European eel (Anguilla anguilla), in which the involvement of cAMP in epinephrine-induced glucose release has been previously observed. Specific binding of CGP was saturable, reversible, and linear as a function of cell number. Analysis of binding data suggested a single class of binding sites, with a Kd of 1.31 nM and a number of approximately 7000 beta-adrenergic receptors per cell. The potency order of specific inhibition of [3H]CGP binding was CGP > propranolol > or = alprenolol >> butoxamine > or = atenolol, while phentolamine and prazosin failed to significantly displace the tracer at concentrations up to 100 microM. The binding kinetics of CGP were closely related to its biological effect. In fact, the drug dose-dependently counteracted the enhancement of intracellular cAMP levels induced by epinephrine in isolated hepatocytes with a Kd of 1.06 nM. Moreover, it antagonized the hormone-induced stimulation of adenylyl cyclase activity in hepatic membranes as well as of glucose release from cells. These data clearly show that beta-adrenergic receptors are coupled to the adenylyl cyclase/cAMP transduction pathway in eel liver.

Studies on fMLP-receptor interaction and signal transduction pathway by means of fMLP-OMe selective analogues

For-Thp-Leu-Ain-OMe ([Thp(1), Ain(3)] fMLP-OMe) (2), for-Met-delta(z)Leu-Phe-OMe ([delta(z)Leu(2)] fMLP-OMe) (3), for-Thp-Leu-Phe-OMe ([Thp(1)] fMLP-OMe) (4), and for-Met-Leu-Ain-OMe ([Ain(3)] fMLP-OMe) (5) are for-Met-Leu-Phe-OMe (fMLP-OMe) (1) analogues which discriminate between different responses of human neutrophils. Peptides 3 and 5, similar to fMLP-OMe, enhance neutrophil cyclic AMP (cAMP) as well as calcium levels, while analogues 2 and 4, which evoke only chemotaxis, do not alter the concentration of these intracellular messengers. When we tested the peptides' ability to displace [3H]-fMLP from its binding sites, the following order of potency was observed: analogue 1 > 3 > 5 > 2 > 4. A particularly low activity at the receptor level characterized analogues 2 and 4. Their low effectiveness was not improved by the addition of cytochalasin B, by different incubation temperatures, or by the absence of endogenous guanine nucleotides, conditions known to influence fMLP receptor fate and functionality. We speculate that, in certain conditions, the fMLP receptor may undergo conformational changes that impede the binding of pure chemoattractants.

Non-selectivity of yohimbine for adrenergic receptors in fish liver

Most studies on adrenergic receptors (AR) have been performed on mammalian tissues, but the adrenergic ligands routinely utilized seem not always suitable for specific interaction with fish tissues. Here we report that in isolated catfish hepatocytes, yohimbine, usually thought to act as a specific antagonist for AR of the alpha2 subtype, at high concentrations, increases adenylyl cyclase activity and synergistically enhances the forskolin-induced enzyme stimulation. Such effects are counteracted by the beta-AR antagonist propranolol, but not by the alpha-AR antagonist phentolamine. Moreover, yohimbine seems to antagonize both alpha1- and alpha2-adrenergic ligand-binding in catfish liver membrane in a manner somewhat different from the mammalian systems. Together with previous evidence that yohimbine blocks the rise of intracellular calcium induced by epinephrine via alpha1-AR, the present results seem to indicate that this compound is not a suitable tool for studying alpha2-AR in fish liver.

Alpha-adrenoceptor-mediated glucose release from perifused catfish hepatocytes

In fish liver catecholamines bind to beta-adrenoceptors (AR) and increase glucose release via cAMP augmentation. Alpha1-AR have recently been shown to mediate IP3 and Ca2+ elevation in catfish and eel hepatocytes, although their coupling to a physiological response has remained doubtful. We have perifused isolated catfish hepatocytes in Bio-Gel P4 columns with epinephrine in the presence of prazosin and/or propranolol, alpha- and beta-AR antagonists, respectively. Ten nM epinephrine stimulated glucose release approximately 3-fold, and this effect was completely antagonized by the simultaneous presence of both alpha- and beta-AR blockers. The two AR antagonists separately inhibited about one-third and two-third of the total stimulation, respectively. Through alpha-AR occupancy, epinephrine provoked a significant increase of glucose release whereas no stimulation was detected in Ca2+-depleted hepatocytes. Glucose release was strongly elevated by both ionomycin and dibutyryl cAMP. These results represent the first direct evidence that alpha-AR transduction pathway is involved in epinephrine-induced glucose release from fish hepatocytes.

Phe-D-Leu-Phe-D-Leu-Phe derivatives as formylpeptide receptor antagonists in human neutrophils: cellular and conformational aspects

We synthesized several Phe-d-Leu-Phe-d-Leu-Phe analogues in which tert-butyloxycarbonyl and four different ureido substituents were included at the N-terminal of the peptides, obtained as free acid and methyl-ester derivatives. Their biological action was analysed on human neutrophil responses induced by N-formyl-Met-Leu-Phe (fMLF). Several in vitro assays were carried out: receptor binding, measurement of Ca2+ intracellular concentration, chemotaxis, superoxide anion production and enzyme release. A conformational investigation, using infrared absorption and circular dichroism, was also performed. Our results demonstrate that the compounds examined prefer an ordered conformation (beta-turn) in amphipathic environment, and are able to antagonize the neutrophil functions evoked by fMLF. Moreover, the extent of inhibition of Ca2+ intracellular enhancement, as well as of superoxide anion production and granule enzyme release, appears related to their affinity toward the formylpeptide receptor. The free acid peptide derivatives appear to be more active antagonists than the methyl-ester ones.

Does formyl-methionyl-leucyl-phenylalanine exert a physiological role in labor in women?

The classical chemotactic receptor for N-formyl peptides has traditionally been associated with polymorphonuclear and mononuclear phagocytes; however, several recent reports indicate that this receptor is also expressed in non-myeloid cells. In this study we have investigated the presence of binding sites for formyl-methionyl-leucyl-phenylalanine (fMLP) in human amniotic membranes of laboring and nonlaboring women; we have also evaluated the effect of the peptide on prostaglandin E (PGE) release from the same tissue. Our results demonstrate the presence of specific, saturable binding sites for 3H-fMLP; Scatchard plot analysis suggests the presence of both high- and low-affinity binding sites in laboring amnion, while only the low-affinity receptors were evident in nonlaboring tissue. N-t-butoxycarbonyl-methionyl-leucyl-phenylalanine (Boc-MLP), a formyl peptide receptor antagonist, inhibited 3H-fMLP binding in both preparations. In addition, fMLP was able to significantly increase PGE synthesis in perifused amnion fragments from laboring and nonlaboring women. This effect was counteracted by Boc-MLP treatment. The presence of specific binding sites for fMLP in amniotic tissue and their differing expression in laboring versus nonlaboring membranes, together with the action of the peptide on PGE synthesis, all suggest a physiological role for fMLP in labor.

Adenylyl cyclase activity and glucose release from the liver of the European eel, Anguilla anguilla

The properties of adenylyl cyclase (AC) in liver membranes of the European eel (Anguilla anguilla) and the involvement of cAMP in glucose release from isolated hepatocytes in response to catecholamines were studied. Basal enzyme activity seemed essentially unaffected by GTP, while a biphasic response to increasing nucleotide concentrations was obtained in the presence of epinephrine. Eel liver AC was dose-dependently stimulated by guanosine 5'-O-(3-thiotriphosphate) and inhibited by guanosine 5'-O-(2-thiodiphosphate). AC activity, intracellular cAMP levels, and glucose release from isolated hepatocytes were significantly enhanced by NaF, forskolin, epinephrine, and phenylephrine. The rise in cAMP production stimulated by catecholamines was counteracted by propranolol, but not by phentolamine. Catecholamine-induced glucose output was instead partially antagonized by both phentolamine and propranolol. Complete inhibition was obtained only by the simultaneous presence of the two adrenergic antagonists. Glucose release from the cells was induced by dibutyryl cAMP and by the calcium ionophore ionomycin. In summary, these data provide the first characterization of eel liver AC system and suggest a direct role for cAMP in the catecholamine-dependent glucose output. Furthermore, the involvement of calcium ions in this cellular response is hypothesized.

fMLP-OMe analogs substituted at the methionine residue: an insight into the receptor properties

In order to obtain an insight into the mode of binding at the for-Met-Leu-Phe-OH (fMLP) receptor, three fMLP-OMe analogs (1-3) were synthesized in which the Met residue was substituted by Gln 1, Asn 2, and Ser 3. We evaluated the influence of the charge variation and/or the shift of its position on neutrophil biological responses.

The role of circulating catecholamines in the regulation of fish metabolism: an overview

The physiological role of the catecholamines (CA), adrenaline and noradrenaline in fish has been frequently reviewed, but the metabolic consequences of these hormones have received less attention. The purpose of this review is to examine the recent literature dealing with CA actions on whole fish and tissue metabolism. The CA increase glucose production both in vivo and in vitro, at least in isolated hepatocytes. Although the data are less clear, lipid mobilization is also a consequence of elevated circulating CA. The difficulty with using the whole fish for such studies is that CA may alter other circulating hormone levels, CA turnover in the circulation quickly, and it is difficult to define precisely the tissue being affected. Much of our understanding is derived, therefore, from the study of isolated tissues, and especially the hepatocyte. Catecholamines stimulate both glycogenolysis and gluconeogenesis in hepatocytes isolated from a large number of fish species. This review examines the steps involved in the signal transduction system, from the binding of CA to alpha- and beta-adrenoceptors to the ultimate effects of specific enzyme phosphorylation. Recent literature demonstrates that the complexity of the adrenoceptor system noted for mammals, also is expressed in fish. Adrenoceptor subtypes are specific to species, to tissues and to function of the tissues, and these issues are discussed especially as they are related to external and to internal stressors. Future research will pursue better definitions of the adrenoceptor systems, molecular biology of the components of these receptor systems and development of alternative cell models. There still remains a poor explanation of the reason for the diversity of adrenoceptor systems, and there are a number of fish systems that may provide unique opportunities to understand this question.

Two for-Met-Leu-Phe-OMe analogues trigger selective neutrophil responses. A differential effect on cytosolic free Ca2+

For-Thp-Leu-Ain-OMe and for-Met-delta(z)Leu-Phe-OMe are two conformationally restricted fMLP-OMe analogues able to discriminate between different biological responses of human neutrophils. In this paper, we demonstrate that the former peptide, which evokes only chemotaxis, does not alter human neutrophil Ca2+ levels. In contrast, for-Met-delta(z)Leu-Phe-OMe, which induces superoxide anion release and degranulation but not chemotaxis, significantly increases the cation concentration. The chelation of Ca2+ in both extracellular and intracellular media abolishes O2- production triggered by for-Met-delta(z)Leu-Phe-OMe, while the same procedure does not affect neutrophil chemotaxis towards for-Thp-Leu-Ain-OMe. We therefore suggest that chemotaxis, unlike superoxide anion release, is independent of Ca2+ enhancement in human neutrophils.

Coexistence of alpha1 and beta adrenergic receptors in the liver of the frog Rana esculenta, the toad Bufo bufo, the lizard Podarcis sicula campestris, and the turtle Pseudemys picta elegans

In mammals and birds the characteristics of alpha1 adrenergic receptors and their biological role in liver metabolism have been clearly described, although the predominance of receptor subtypes varies with species. In contrast, the actual presence of hepatic alpha1 adrenergic receptors in fish, amphibians, and reptiles has been questioned. Only recently has their existence been demonstrated in some fish species and also in the wood frog Rana sylvatica. The present study assessed the presence of alpha1 adrenergic binding sites on hepatic membranes of frogs, toads, lizards, and turtles using the specific alpha1 adrenergic receptor antagonist [3H]prazosin; for comparison, the binding of the specific beta adrenergic receptor antagonist [3H]CGP-12177A was evaluated in the same preparations. alpha1 Adrenergic receptors are indeed present in the liver of the ectotherms examined. Specific binding is saturable, reversible, and linear as a function of tissue concentration. The binding data indicated the presence of two classes of binding sites displaying high and low affinities with Kds in the nanomolar and micromolar ranges, respectively. The present study provides the first evidence for the presence of alpha1 adrenergic receptors in the liver of toad, lizard, and turtle while confirming their existence in another species of frog, Rana esculenta.

Neurochemical changes in cerebellum of goldfish exposed to various temperatures

Acclimation of goldfish at 35 degrees C increased the cerebellar content of aspartate, glutamate, and taurine and [3H]glutamate uptake. Acclimation at 4 degrees C increased the levels of glutamine, serine, and alanine and glutamine synthetase (GS) activity. Adenosine content increased in cerebellum of fish acclimated to warm temperature. K+-evoked release of endogenous and exogenous glutamate from cerebellar slices increased in fish acclimated at 35 degrees C compared to 4 degrees C. The basal level of cyclic adenosine 3':5'-monophosphate (cAMP) in perfused cerebellar slices in fish acclimated at 35 degrees C was much higher than in fish acclimated at 5 degrees and 22 degrees C. It is concluded that variations of environmental temperature produces large neurochemical changes in goldfish cerebellum.

Modifications of the amide bond at position 3 in fMLP analogs select neutrophil functions

The formylpeptides formyl-L-methionyl-L-leucyl-L-N-methylphenylalanine methyl ester 1, formyl-L-methionyl-L-leucyl-L-2-oxy-3-phenylpropionic acid methyl ester 2 and formyl-L-methionyl-L-leucyl-L-2-aminoxy-3-phenylpropionic acid methyl ester 3 were synthesized to investigate the role of the amide bond at position 3 in biological activity in human neutrophiles. Our results indicate that this amide bond is required for optimal chemotactic activity, but not for superoxide anion production.

Effectiveness of pentoxifylline in semen preparation for intrauterine insemination

Pentoxifylline, an inhibitor of cAMP phosphodiesterase activity, favours intracellular cAMP concentration increase. In-vitro treatment of semen with pentoxifylline leads to marked augmentation of sperm motility, enhancement of acrosome reaction, increase of sperm penetration into zona-free hamster oocytes, and protection of the sperm plasma membrane. Such properties indicate that the drug may be a useful tool for semen preparation in assisted reproduction, but its real effectiveness in improving fertilization rates is still uncertain, mainly in association with intrauterine insemination (IUI). Theoretically sperm motility should play an extremely important role for positive results in IUI. Therefore, a retrospective clinical trial was planned in order to evaluate whether addition of pentoxifylline to the previously standardized in-vitro treatment of semen had improved the percentage of pregnancies after homologous IUI. The study involved 55 sterile couples (33 classified infertile for male factor and 22 for other factors) who underwent a total of 150 cycles of homologous IUI: 101 for male factor infertility and 49 for other factors (anovulation n = 26, endometriosis n = 2, idiopathic n = 21). Out of the 101 cycles performed for male factor infertility, 61 underwent the standard preparation of semen and were followed by seven pregnancies (pregnancy rate = 11.5%) while 40 had a semen preparation with pentoxifylline addition and were followed by 11 pregnancies (pregnancy rate = 27.5%) with a significant difference between the two procedures (P < 0.05). Out of the 49 cycles carried out for factors different from male infertility, 10 underwent the standard preparation of semen and were followed by two pregnancies (pregnancy rate = 20.0%), while 39 had pentoxifylline addition and were followed by nine pregnancies (pregnancy rate = 23.1%). The difference between the two groups was not significant. Abortions and malformations were equally distributed in the standard treatment and in the pentoxifylline group.

Effects of Ca2+ and calmodulin on adenylyl cyclase activity in sheep olfactory epithelium

Sheep olfactory epithelium contains an adenylyl cyclase which is stimulated by many but not all odorants. Here we report that this enzyme is activated by calmodulin in a dose-dependent manner, and that calcium ions are required for this response. Odorant stimulation of adenylyl cyclase is unaffected by the complex Ca2+/calmodulin, as suggested by the results obtained both in Ca2+/calmodulin-depleted membranes and under calmodulin antagonist treatment; this confirms the prediction that the Ca2+ binding protein and odorants stimulate the olfactory adenylyl cyclase through parallel mechanisms. The persistent activation of the regulatory component of adenylyl cyclase by GppNHp does not alter the response of the enzyme to either odorant or Ca2+/calmodulin. In sheep olfactory epithelium a cAMP-phosphodiesterase activity is also present, which is highly inhibited by IBMX and aminophylline, scarcely by RO 20-1724, and unaffected by Ca2+/calmodulin. The modulatory role exerted by calcium on cAMP system in sheep olfactory signal transduction is discussed.