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Biomedical subjects

A Meli

Publications and source records attributed to A Meli.

At least 19 recordsLinked to original sources
PubMed2006

Vestibular rehabilitation and 6-month follow-up using objective and subjective measures.

CONCLUSIONS: Vestibular rehabilitation improves quality of life by reducing the degree of handicap, improving the ability to perform everyday tasks and providing long-term rehabilitation stability (at 6 months). Recovery of the vestibulo-ocular reflex and the vestibulo-spinal reflex efficiency was proven by the objective results obtained in this study. Vestibular rehabilitation improves both subjective and objective parameters, although no significant correlation between these two indices was found. OBJECTIVE: To determine the outcome of subjective and objective parameters and long-term rehabilitation stability after vestibular rehabilitation in 43 patients with vestibular disorders. MATERIAL AND METHODS: The subjective tests used were the Medical Outcomes Study 36-item Short Form, the Dizziness Handicap Inventory and the Activity-specific Balance Confidence scale. The objective tests used were video-oculoscopy, dynamic visual acuity, the Equitest and the Dynamic Gait Index. All indices were evaluated before and after rehabilitation and at follow-up. RESULTS: All patients showed an improvement in quality of life and a reduction in handicap due to dizziness. Improvement in objective test results was also seen. These results were stable at follow-up. A correlation was found between different subjective measures, but there was no correlation between subjective and objective measures.

Adult↗
PubMed2001

Standardization of the comet assay technique on FRTL5 cells.

The comet assay is a sensitive and rapid method for DNA strand break detection in individual cells. The principle of break detection, using either the alkaline or neutral version of the assay, makes it a good technique for studying both double and single strand DNA breaks. Furthermore, the possibility of following DNA damage at different time moments also makes it possible to investigate the cell repair mechanisms. This explains why in the last few years there has been a tremendous increase in the number of laboratories which started to use this technique. The technique was first created for lymphocyte cells and later on has been used on many other cell types, growing both in suspension and adherent. To date, no one has applied this technique on normal differentiated endocrine cells, such as FRTL5 cells (Fisher Rat Thyroid Cells). The aim of this study has been to standardize the alkaline version of the Comet Assay technique on FRTL5 cells by studying the kinetics of DNA-damage and DNA-repair after different doses of UV-C (254 nm). FRTL-5 cells not only resulted very sensitive to UV-C (p<0.05 at 5 J/m2), but were also able to repair most of their DNA damage very rapidly (within one hour) as shown by a significant exponential regression in comet length. Finally, the successful measurement of biomarkers of UV-C on thyroid cells established the comet assay as a valuable tool in measurement of DNA damage and repair. Any radiation, or other damaging agents, interacting with living organisms could cause DNA damages which, depending upon dosages and kinetics of exposure, may or may not be completely repaired.

Animals↗
PubMed2001

Radiation-dependent apoptosis on cultured thyroid cells.

Aim of this investigation is the study of the modifications and the DNA damage occurring in thyroid cells exposed to radiation. The FRTL-5 rat thyroid cell strain has been chosen for this study. Objects of this research are both Ionizing radiation, of fundamental interest for space missions, and the UV radiation, (also mutagen and frequent cause of several cancer forms). The present study of UV radiation represents a preliminarily tool to investigate the biological radiation damage. FRTL-5 cells have been irradiated with doses of UV-C (254 nm wavelength) ranging from 15 to 80 Joule/m2. The DNA damage has been analyzed with the 'DNA ladder by gel electrophoresis' technique. DNA has been extracted at 24 and 48 hours from irradiation. At 24h the apoptotic process is not detectable. At 48 h from irradiation, cells show the characteristic signs of apoptosis. The lower dose to which the apoptotic process is detectable, corresponds to 20 Joule/m2. At the higher doses a bigger percentage of cells undergoes apoptosis. These data confirms that the FRTL-5 biological system is particularly suitable for further studies on the biological mechanisms of radiation damage.

Animals↗
PubMed1999

In vitro cultured cells as probes for space radiation effects on biological systems.

Near future scenarios of long-term and far-reaching manned space missions, require more extensive knowledge of all possible biological consequences of space radiation, particularly in humans, on both a long-term and a short-term basis. In vitro cultured cells have significantly contributed to the tremendous advancement of biomedical research. It is therefore to be expected that simple biological systems such as cultured cells, will contribute to space biomedical sciences. Space represents a novel environment, to which life has not been previously exposed. Both microgravity and space radiation are the two relevant components of such an environment, but biological adaptive mechanisms and efficient countermeasures can significantly minimize microgravity effects. On the other hand, it is felt that space radiation risks may be more relevant and that defensive strategies can only stem from our deeper knowledge of biological effects and of cellular repair mechanisms. Cultured cells may play a key role in such studies. Particularly, thyroid cells may be relevant because of the exquisite sensitivity of the thyroid gland to radiation. In addition, a clone of differentiated, normal thyroid follicular cells (FRTL5 cells) is available in culture, which is well characterized and particularly fit for space research.

Animals↗
PubMed1999

Response to thyrotropin of normal thyroid follicular cell strain FRTL5 in hypergravity.

Thyroid hormones control every cell in the organisms and, as indicated by many hormonal changes in astronauts during and shortly after space missions, its complex regulation may be influenced by gravity. To test in vitro the effects of gravity environment on thyroid, we selected a unique cultured cell system: the FRTL5, a normal follicular thyroid cell strain in continuous culture, originally derived from adult rat thyroids. To establish if modifications of the gravitational environment may interfere with post-receptorial signal transduction mechanisms in normal mammalian cultured cells, following our previous microgravity experiments, we exposed thyrotropin-stimulated and unstimulated FRTL5 cells to hypergravity (5 g and 9 g) in a special low-speed centrifuge. At all thyrotropin doses tested, we found significant increases in terms of cyclic AMP production in FRTL5 thyroid cells. The data here reported correlate well with our previous microgravity data, showing that the FRTL5 cells functionally respond to the variable gravity force in a dose-dependent manner in terms of cAMP production following TSH-stimulation.

Animals↗
PubMed1993

Effects of terflavoxate on stimulated contractions of urinary bladder in vitro.

The antispasmodic activity of terflavoxate (CAS 86433-39-8), a flavone derivative with spasmolytic properties on the urinary tract, has been studied in vitro, in comparison to the most common drugs utilized in the therapy of overactive detrusor, namely flavoxate, oxybutynin, and terodiline. Terflavoxate showed affinity for bladder (and brain) muscarinic receptors at micromolar level, however, its activity on carbachol-induced contractions of rat bladder was clearly non competitive, indicating that the compound is devoid of functional antimuscarinic property. Moreover, the observation that unlike antimuscarinic drugs, terflavoxate inhibited by more than 50% field stimulation-induced contractions of rabbit bladder strips, indicates that mechanisms other than the anticholinergic one should be responsible for its smooth muscle relaxant properties. Terflavoxate, flavoxate, oxybutynin, and terodiline were equally effective in inhibiting the two components of K(+)-induced contractions, while nifedipine and nicardipine were more potent than the other compounds, and more effective in inhibiting tonic than phasic contractions. In addition, while nifedipine and nicardipine antagonized in a competitive manner calcium-induced contractions of potassium-depolarized bladder strips, the other spasmolytics behaved as mixed antagonists. Differences in calcium antagonistic properties between nifedipine and nicardipine on one side, and terflavoxate on the other, are further demonstrated by the data on binding experiments. Nevertheless, present results suggest that Ca(++)-antagonistic effects are mainly responsible for terflavoxate smooth muscle relaxant properties.

Animals↗
PubMed1991

Effect of psychotomimetics and some putative anxiolytics on stress-induced hyperthermia.

Stress-induced hyperthermia (SIH), which is seen in the last mice removed from the cage, is a novel animal model sensitive to anxiolytic drugs. SIH is antagonized by CL 218872 (25 and 50 mg/kg, os), by tracazolate (5 and 7.5 mg/kg, ip) and by 2-AP-5 (50 and 100 mg/kg, ip). At higher dose, CL 218872 (100 mg/kg, os) and tracazolate (12.5 mg/kg, ip) lose their activity. PK 9084 (5-40 mg/kg, ip) and CGS 9896 (2-20 mg/kg, both ip and os) were also ineffective in preventing SIH. The anti-hyperthermic effect of CL 218872 (25 mg/kg) and tracazolate (7.5 mg/kg) was blocked by the benzodiazepine antagonist Ro 15-1788 (15 mg/kg), CGS 9896 (10 mg/kg, os) also reversed the effect of CL 218872 (25 mg/kg) on SIH. Differently from anxiolytics, MK-801 (0.5-1 mg/kg, os), PCP (2.5 mg/kg, ip) and d-amphetamine (10 mg/kg, ip) evoked hyperthermia in the first set of mice and prevented a further stress-induced rise of body temperature in the last set of mice.

2-Amino-5-phosphonovalerate↗
PubMed1991

Effect of enantiomers of propranolol on desipramine-induced anti-immobility in the forced swimming test in the rat.

The effect of d- and l-enantiomers of propranolol on desipramine-induced anti-immobility effects and on brain desipramine levels was studied in the rat. Intraperitoneal propranolol and desipramine were administered three times, 25, 6, 2 and 24, 5, 1 h respectively, before the test. It was found that l-propranolol but not d-propranolol, at the same doses (2.5 and 5 mg/kg), antagonized 20 mg/kg desipramine without altering desipramine brain levels. It is suggested that blockade of beta-adrenergic receptors rather than membrane-stabilizing or pharmacokinetic effects is responsible for the antagonism of propranolol toward desipramine.

Animals↗
PubMed1991

New dibenzothiadiazepine derivatives with antidepressant activities.

A new series of 11-[(aminoalkyl)carbonyl] derivatives of 6,11-dihydrodibenzo[c,f][1,2,5]thiadiazepine 5,5-dioxide (10-39) were synthesized and evaluated for potential antidepressant activity in the apomorphine-induced hypothermia (Apo 16) test. Effects on reserpine-induced hypothermia and toxicity for the most potent antagonists of Apo 16 hypothermia were also studied. Structure-activity relationships are reported. Anticholinergic effects were evaluated for compound 12, identified as the most potent and least toxic in this series, by assessing physostigmine lethality. Compound 12 was also subjected to X-ray analysis.

Animals↗
PubMed1991

Potential antidepressant activity and enhancement of serotonin uptake of a new dibenzothiadiazepine derivative.

A molecule, 6-methyl-6,11-dihydro-11-[(N,N-dimethylamino) acetyl]dibenzo[c,fl-[1,2,5]thiadiazepine 5,5-dioxide, (IM/P/3/4, CAS 128377-70-8), was identified in a screening program, which had the scope of finding compounds with antidepressive potential without the common sideeffects of existing antidepressive medication. IM/P/3/4 was found active a) in antagonizing apomorphine (16 mg/kg) and reserpine-induced hypothermia in mice; b) in potentiating yohimbine-induced lethality in mice; c) in reducing immobility of rats forced to swim and of mice suspended by the tail. IM/P/3/4 does not affect a) apomorphine-induced stereotypy; b) amphetamine-induced hypermotility; c) haloperidol-induced catalepsy and water-induced grooming and d) does not induce stereotypy or alter motor activity. The compound also a) reduced the beating of rat right heart atria only at a concentration of 3 x 10-4 mol/l; b) had weak anticholinergic activity; c) antagonized electroshock-induced convulsions and d) prevented indometacin-induced duodenal ulcers. IM/P/3/4 does not have good affinity for noradrenergic, serotonergic, dopaminergic, histaminergic or muscarinic receptors and does not displace imipramine, desipramine and mianserine from their binding sites. IM/P/3/4 increases 5-hydroxyindolacetic acid content and 3H-serotonin uptake in the hypothalamus. The present results suggest that IM/P/3/4 is a potential antidepressant with reduced side effects and with a mechanism of action which is different from that of other antidepressants.

Anesthetics↗
PubMed1990

Direct evidence for the involvement of vasoactive intestinal polypeptide in the motor response of the human isolated ileum to capsaicin.

Capsaicin (1 microM) produced complex motor responses in longitudinal and circular muscle strips from the human isolated small intestine (jejunum and ileum). In the longitudinal muscle, inhibition of the nerve-mediated contractions (electrical field stimulation) was the dominant response, while capsaicin had a weak and inconsistent effect on tone and spontaneous activity. In contrast, relaxation and decreased spontaneous activity were the responses of the circular muscle to capsaicin. These effects of capsaicin were not reproduced by a second application of capsaicin, indicating desensitization, a feature of the specific action of this drug on sensory nerves. All the effects of capsaicin in the longitudinal and circular muscle were closely mimicked by exogenous vasoactive intestinal polypeptide (VIP). Further, the inhibitory motor effect of capsaicin in both muscle layers was blocked by an anti VIP serum. In the longitudinal muscle, VIP, like capsaicin, inhibited the electrically evoked nerve-mediated contractions but not the tetrodotoxin-resistant myogenic contractions, suggesting a prejunctional site of action. The inhibitory effect of both capsaicin and VIP in the circular muscle was tetrodotoxin-resistant suggesting direct inhibition of muscle cells. Capsaicin (1 microM) evoked a tetrodotoxin-resistant release of VIP-like immunoreactivity from the human small intestine. On high pressure liquid chromatography, a major peak of the immunoreactive material released by capsaicin co-eluted with authentic VIP and a minor, unidentified peak eluted shortly afterward. We conclude that authentic VIP is involved in the local motor response to capsaicin in the human small intestine. These findings raise the possibility that VIP might be present in sensory nerves of the human gut from which it is released by capsaicin.

Aged↗
PubMed1990

The effect of MK-801 on the micturition reflex in anesthetized rats.

We studied the effect of MK-801, a potent non-competitive NMDA receptor antagonist, on the micturition reflex in anesthetized rats. Pretreatment with MK-801 (0.1-1 mg/kg i.v.) dose dependently increased the bladder capacity and reduced the micturition contraction. The ability of MK-801 to inhibit bladder voiding was confirmed in additional experiments in which the compound (30-50 micrograms/kg i.v.) transiently suppressed established bladder voiding produced by continuous bladder filling. MK-801 (1 microM) did not affect nerve-mediated contractions of the rat bladder or inhibit the response to capsaicin. These findings provide pharmacological evidence for an involvement of NMDA receptors in the micturition reflex pathways.

Anesthesia↗
PubMed1990

Duodenal SP-like immunoreactivity is decreased in experimentally-induced duodenal ulcers.

Substance P-like immunoreactivity (SP-li) is decreased in duodenal samples of animals treated with a single dose of an ulcerogen such as dulcerozine, mepirizole or cysteamine. Unlike dulcerozine- or mepirizole-induced ulcers the degree of cysteamine-induced duodenal lesions is inversely correlated with the levels of duodenal SP-li. A significant decrease in duodenal SP-li was observed at 24 h, but not at 6 h after a single oral dose of cysteamine. These findings show that endogenous SP may play an important local role in duodenal ulcerogenesis.

Animals↗
PubMed1990

Biological activity of N-terminal fragments of calcitonin gene-related peptide.

The i.v. injection of human alpha-calcitonin gene-related peptide (CGRP) in urethane-anesthetized rats produced hypotension and tachycardia. The N-terminal fragments, CGRP-(1-12), CGRP-(1-15) and CGRP-(1-22) displayed biological activity, although with less potency than the natural peptide. These findings provide the first evidence for biological agonist activity of N-terminal CGRP fragments.

Animals↗
PubMed1990

In vivo pharmacology of [beta Ala8]neurokinin A-(4-10), a selective NK-2 tachykinin receptor agonist.

We studied the effect of [beta Ala8]neurokinin A-(4-10), a newly developed selective NK-2 tachykinin receptor agonist, on various parameters in anaesthetized rats (blood pressure, urinary bladder motility, plasma extravasation) and guinea-pigs (salivation, increase of pulmonary insufflation pressure) as compared to the response produced by tachykinins. [beta Ala8]Neurokinin A-(4-10) was as active as, or more active than, neurokinin A (NKA) or NKA-(4-10) in producing rat bladder contraction or bronchospasm in guinea-pigs, two effects known to involve activation of NK-2 receptors. On the other hand, the synthetic peptide was weakly active, if active at all, in producing hypotension or plasma extravasation in the rat bladder as well as salivation in guinea-pigs, effects known to involve activation of NK-1 receptors. These findings provide evidence that [beta Ala8]NKA-(4-10) acts as a selective NK-2 agonist in vivo and that it can be used to explore the distribution and function of NK-2 receptors.

Anesthesia↗