Cecropia hololeuca: A new source of compounds with potential anti-inflammatory action.

Our objective is to investigate the phytochemical components, antioxidant capacity and in vitro and in vivo anti-inflammatory action from Cecropia hololeuca bark aqueous extract (AECh). The chemical characterization of AECh was performed through CE-UV, FTIR and NMR Spectroscopy. In vitro assays were performed with the AECh on murine macrophages J774A.1 cells in order to analyse cell viability, NO, TNF-α and IL-1ß productions and the in vivo anti-inflammatory potential in acute carrageenan paw oedema in mice. The AECh showed a decrease in the production of NO, TNF-α and IL-1ß, without altering the cell viability and reduction of the paw thickness in the 2nd, 3rd and 4th hour. The extract presented 72% free radical scavenging, 0.60% flavonoid content and showed the presence of gallic acid, caffeic acid and catechin as major constituents. The C. hololeuca bark extract showed important antioxidant and anti-inflammatory activity, emphasizing the industrial and pharmacological potential of this plant.

A dynamic population of excitable cells: the taste receptor cells.

Taste receptor cells (TRCs) represent an unique opportunity to study a dynamic population of excitable cells that undergoes two basic neurobiological processes: postnatal development and cell turnover. We have begun to investigate the functional properties of TRCs and how they mature over time by applying the patch-clamp technique to single cell in taste buds isolated from mouse vallate papilla during postnatal development. We have focussed our attention on a well-defined functional group of taste cells, called Na/OUT cells, and on their voltage-gated K+, and Cl- currents (I(K) and I(Cl), respectively). As in neurons, I(K) and I(Cl) underlie action potential waveform and firing properties in these cells. By analyzing the relative occurrence of I(K) and I(Cl) among cells, we found that in adult mice three different electrophysiological phenotypes of Na/OUT cells could be detected: cells with only I(K) (K cells); cells with both I(K) and I(Cl) (K + Cl cells); and cells with I(Cl) (Cl cells). On the contrary, at early developmental stages (2-4 postnatal day, PD) there were no Cl cells, which appeared at PD 8. The analysis of the changes in current amplitude (which continuously increased in developing cells) during postnatal development suggested that Cl cells and K + Cl cells likely represented a single functional line different from K cells. In addition, electrophysiological data were consistent with the interpretation that Cl cells derived from some K + Cl cells by suppression of I(K). The dynamics of the expression of I(K) and I(Cl) during postnatal development likely reflects a mechanism that could also operate during turnover.

Reflex cardiac response to various olfactory stimuli in the blowfly, Protophormia terraenovae.

In the present investigation it is shown that a reflex change in the heart activity of Protophormia flies is evoked by olfactory stimulation with several volatile substances, and particularly with those which are repellent for blowflies. Among these, i-pentanal and hexanal vapours evoked a fast, highly persistent cardiac response, whereas in the case of hexanol and ammonia vapours the response resulted slower and could be suppressed as a function of repeated stimulation.

Cell growth inhibitory effects of caulerpenyne, a sesquiterpenoid from the marine algae Caulerpa taxifolia.

Caulerpa taxifolia (Vahl) C. Agardh (Ulvophyceae, Caulerpales) is an algae of tropical origin that was accidentally introduced into the Mediterranean in 1984. Caulerpenyne (Cau) is the major metabolite present in Caulerpa taxifolia. This metabolite has previously been shown to be cytotoxic against cell lines in culture as in KB cells and fibroblasts from hamsters. Cau along with 6 other drugs representative of the major classes of anticancer products was tested against 8 cancer cell lines of human origin. Cau demonstrated growth-inhibitory effects in all cases with some variability between cell lines; this inter-cell variability was, however, less marked than that observed with the anticancer drug tested. Cells of colorectal cancer origin were the most sensitive to the presence of Cau with IC50 values of 6.1 and 7.7 microM. Increasing the duration of contact between Cau and the cells from 75 min to 29.5 hr did not improve the cytotoxic efficacy of this compound. When Cau was pre-incubated in the culture medium for from 7 to 83 min before being exposed to CAL 27 cells (head and neck cancer origin), there was a constant loss of cytostatic action of Cau as a function of Cau pre-incubation time. As the bovine serum albumin concentration increased in the culture medium, the concentration-response curves showed a constant shift towards the right, indicating a loss of cytostatic activity of Cau. In the presence of Cau, cells in culture clearly exhibited an early and marked shift into S phase followed by a blockade into the premitotic G2 M phase. Possible targets for CAU remain to be identified. Cau needs to be tested on tumor bearing animals to confirm this promising antiproliferative activity.

Electrophysiological recordings from the taste chemosensilla of Tabanus nigrovittatus (Diptera: Tabanidae) and determination of behavioral tarsal acceptance thresholds.

A modified behavioral test for determining the median tarsal acceptance thresholds of field-collected, female Tabanus nigrovittatus Macquart to sugars showed that flies were sensitive to the three major nectar sugars (fructose, sucrose, and glucose, in that order of decreasing sensitivity) whereas galactose, a nonnectar sugar, was not comparably stimulating. Comparisons of various treatment effects on the median tarsal acceptance thresholds showed that for future studies, flies should be fed 10% sucrose before testing, should be starved for 24 h before testing, and they do not have to be pretested for a water response. Electrophysiological recordings showed that gustatory chemosensilla were located on the labellum, tip of labrum, labral food canal, foretarsi, tibia, and antennae. All chemosensilla responded to sugar and salt, whereas only those chemosensilla at the tip of the labrum and those lining the food canal, which normally contact the blood meal, responded to sera and plasma.

Oxygen availability, dietary restriction and transport of glucose 3-O-methylglucose and fructose in the isolated small intestine of rat.

The influences of PO2 of the incubating medium on glucose, 3-O-methylglucose and fructose transport by everted small intestine sacs in semistarved and rats fed ad libitum (controls) was investigated. Moreover fructose uptake and conversion to glucose by intestinal sacs was also studied. The results showed that intestinal sacs from semistarved rats transported larger amounts of glucose and 3-O-methylglucose and took up more fructose than controls, when PO2 of the incubating medium was 150 mm Hg. There was greater fructose conversion to glucose in the intestine of semistarved rats than in controls at all PO2's considered. The greater functional capacity of intestinal tissue of semistarved rats in comparison to controls has been related to larger O2 availability in their intestinal wall.

Effects of Ba ions on frog's isolated muscle spindle.

Dilute solutions of Barium Chloride have been tested on frog's isolated muscle spindles with the aim of clarifying the processes leading to the afferent discharge. In the presence of Ba++ the spindle properties are modified as follows: 1. The discharge of slack spindles increases and becomes extremely regular. 2. The phasic response to stretching is enhanced, the tonic responses being on the contrary virtually suppressed. Under Ba-treatment therefore the spindle changes from a phasic-tonic receptor to a merely phasic receptor. 3. The "silent period" following every propagated spike is prolonged while the safety margin of the "abortive" into propagated spike conversion becomes maximal under Ba-treatment. Additionally, this analysis showed that, when a "true" action potential arises in the spindle, it propagates not only to the stem fibre, but also to all the sensory endings in the spindle intracapsular network. Comparison between the effects of Ba++ and those produced by TEA and ouabain indicates that the action of Ba++ on muscle spindles results from conjunction of two factors : a) reduction of K permeability, and b) enhanced efficiency of an electrogenic Na/K-pump in spindle nerve membranes.

Functional importance of the taste papillae of Phormia regina M.

Electrophysiological recording from taste papillae of Phormia regina M. after stimulation with sugar (sucrose, glucose, fructose and galactose) and salt solutions (NaCl, KCl, KNO3 and CaCl2) has indicated that: 1) in all cases the responses showed a phasic onset about 30 sec in duration; 2) after sugar stimulation the phasic onset of the response was followed by a slow adapting tonic period; 3) no tonic period was present after NaCl, KCl, or KNO3 stimulation; 4) CaCl2 evoked a typical volleying activity that can be explained by a greater spatial spreading of electrotonic currents. These results indicate that the proboscis can only be maintained in an extended position (enabling food to be ingested) by rithmic firing from the papillae.

The presence of acid mucopolysaccharides in viscous extrusions from the labellar and tarsal chemosensilla of Phormia regina (Meig.).

Mucopolysaccharide substances are present in the shafts of both tarsal and labellar chemosensilla of Phormia. These substances are extruded at the tip of the chemosensilla. A certain amount of mucopolysaccharides can also be observed on the outer surface of the tarsal hair wall at various points along the hair shaft. The influence of mucopolysaccharide substances on hair responsiveness to external stimuli is discussed.

Electrical resistance of labellar taste hairs in the blowfly, Phormia regina M., as a function of age and sex.

The electrical resistance of the labellar taste hairs of Phormia regina M. is enhanced by aging in both males and females; this increase is greater in males. Resistance variations, related to changes in response of stimulated chemoreceptors, may explain, at least in part, the reduction in reflex food intake, O2 consumption, weight increase and, on the whole, survival capabilities of males vis-à-vis female insects.

Electrophysiological characterization of a putative supporting cell isolated from the frog taste disk.

Chemosensory cells in vertebrate taste organs have two obvious specializations: an apical membrane with access to the tastants occurring in food, and synapses with sensory axons. In many species, however, certain differentiated taste cells have access to the tastants but lack any synaptic contacts with axons, and a supportive rather than chemosensory function has been attributed to them. Until now, no functional data are available for these taste cells. To begin to understand their role in taste organ physiology, we have characterized with patch-clamp recording techniques the electrophysiological properties of a putative supporting cell-the so-called wing cell-isolated from frog taste disks. Wing cells were distinguished from chemosensory elements by the presence of a typical, sheet-like apical process. Their resting potential was approximately -52 mV, and the average input resistance was 4.8 GOmega. Wing cells possessed voltage-gated Na+ currents sensitive to TTX, and an inactivating, voltage-gated K+ current sensitive to TEA. Current injections elicited single action potentials but not repetitive firing. We found no evidence for voltage-gated Ca2+ currents under various experimental conditions. Amiloride-sensitive Na+ channels, thought to be involved in Na+ chemotransduction, were present in wing cells. Many of the membrane properties of wing cells have been also reported for chemosensory taste cells. The presence of ion channels in wing cells might be suggestive of a role in controlling the microenvironment inside the taste organs or the functioning of chemosensory cells or both. In addition, they might participate directly in the sensory transduction events by allowing loop currents to flow inside the taste organs during chemostimulation.

Chronic electrode for long-term electrophysiological recording from insect chemosensilla.

Insertion of a chronic, non-damaging Pt electrode for electrophysiological recording from chemosensilla in Phormia is described. The experimental procedure did not modify in a significant way the survival capabilities or the general behaviour of the operated insects as compared to control, untreated ones. This method, which allows the performance of subsequent tests on the same specimen up to its full lifespan with fairly constant results, proved to be suitable in long-term experiments on the chemosensory function of insects.

Mechanism of JH influence on the function of labellar chemosensilla in Phormia: experimental suggestions.

The aim of this research study was to determine at which level the JH effect of increasing chemosensillar sensitivity in Phormia could take place. Two-day-old adult female Phormia regina (Meigen) flies were used. Variations in electrical resistance and spike firing frequency of labellar chemosensilla stimulated with NaCl solutions were measured before and after topical application of a JH analogue (JHA). Variations in the above two parameters were also determined in a group of control flies. Results showed that an inverse linear relationship exists between electrical resistance and spike firing frequency in both JHA-treated and control flies. On this basis, we conclude that the above sensitivity variations depend on a mechanism common to both groups of flies. As regards the mode of action of this mechanism, we suggest that JH may influence the mucopolysaccharide secretory function of the accessory cells, the activity of which seems to account for changes in electrical resistance and therefore in sensitivity of the labellar chemosensilla.

Electrophysiological activity of labellar and tarsal chemosensilla of Hybomitra lasiophtalma (Macquart) to stimulation with NaCl and various sugars.

The responses from labellar and tarsal chemosensilla of Hybomitra lasiophtalma to stimulation with NaCl or sugars (sucrose, glucose, fructose, galactose) were recorded. Results showed that 4 chemosensory units were located in each chemosensillum. Among these, a water-, a salt-, and a sugar-sensitive unit were detectable. NaCl (higher than 50 mM) as well as sucrose (higher than 100 mM) sensitivity thresholds were determined; sucrose and galactose proved to be more active as stimuli than fructose and glucose.

Ovipositor chemosensilla in Tabanus nigrovittatus (Macq.) Chrysops fuliginosus (Wied.), and Rhagoletis pomonella (Walsh).

The possible presence of chemosensilla in the ovipositor region has been investigated in three different pest insect species by means of the standard tip-recording electrophysiological technique. Results showed that hair-like structures responding to chemical stimulation were located at the lower-inner edge of the anal leaflets in Tabanus nigro Macq. as well as in Chrysops fuliginosus Wied, whereas peg-like chemosensilla proved to be located in two longitudinal grooves at the apical portion of the ovipositor in Rhagoletis pomonella Walsh.. At least 3 chemosensory units could be detected in each chemosensillum tested. No hair-or peg-like structure on the ovipositor region other than that we described showed any chemosensory responsiveness.

The labellar and tarsal chemosensilla in Anopheles maculipennis atroparvus Van Thiel: electrophysiological and morphological observation.

The presence of chemosensilla on labella and tarsi of Anopheles m.a. has been demonstrated by means of morphological (S.E.M.) and electro physiological (tip-recording) techniques. Results have shown that: 1) at least 3 chemosensory units are located in both types of chemosensilla; 2) stimulation with NaCl evoked various response patterns depending on NaCl concentration in the labellar chemosensilla and just a single pattern in the tarsal ones.

Prevalence of diphtheria toxin antibodies in human sera from a cross-section of the Italian population.

A polycentric study was carried out between 1993 and 1995 in order to evaluate diphtheria immunity on a representative sample of population from different areas of Italy. To determine diphtheria antitoxin, sera from 5187 apparently healthy subjects, divided according to sex and age groups, were titrated using an ELISA indirect method. A basic protective titre of diphtheria antitoxin (> 0.01 IU ml-1) was found in 4080 (78.6%) subjects. No statistically significant differences between males and females were observed. Our findings show that the proportion of susceptibles increases with age and a high proportion of adults no longer has diphtheria antitoxin at protective levels since toxigenic C. diphtheriae circulation is presently lacking in Italy.