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Biomedical subjects

F Sala

Publications and source records attributed to F Sala.

At least 73 records · Page 4Linked to original sources
PubMed1994

Ruthenium red inhibits selectively chromaffin cell calcium channels.

The effect of Ruthenium red (RR) on ionic currents and catecholamine secretion was studied in chromaffin cells. This polycation inhibited 59 mM potassium-stimulated 45Ca2+ uptake in a concentration-dependent manner (IC50 = 5 +/- 0.2 microM). This effect was more evident at extracellular calcium concentrations over 1 mM and was not abolished by neuraminidase pretreatment. RR also inhibited potassium-stimulated catecholamine secretion (IC50 = 6 +/- 0.9 microM). These results were corroborated by patch-clamp in whole-cell recordings. RR inhibited chromaffin cell calcium currents (IC50 = 7 microM) without affecting significantly either sodium or potassium currents. Radioligand binding studies in adrenomedullary plasma membranes showed that RR inhibited [125I]omega-conotoxin GVIA binding but it had no effect on specific binding of [3H]nitrendipine. The effect of the RR on calcium currents was additive with the inhibitory effect observed with 10 microM nitrendipine. The residual dihydropyridine-resistant calcium current was inhibited with a potency similar to that determined under control conditions in the absence of nitrendipine. These results demonstrate that RR selectively inhibits calcium channels; however, this polycation was not selective for a particular calcium channel subtype.

Animals↗
PubMed1994

Sources of errors in different single-electrode voltage-clamp techniques: a computer simulation study.

The use of voltage clamp with a single electrode has been useful in estimating kinetic parameters for a number of ionic whole-cell currents. There are two main types of such a technique: discontinuous voltage clamp (dSEVC) (Brennecke and Lindemann, 1974), and continuous voltage clamp (cSEVC) (Hamill et al., 1981). We have studied, by means of computer simulations, the performance of both types of clamp on estimating activation kinetics parameters of a typical neuronal Ca2+ current. Deviations from the theoretical values are shown to be sensitive on both set-up and cell properties. Both types of clamp are shown to lose voltage control when either access resistance or absolute membrane conductance are increased. In contrast, changes in membrane capacitance affect differently to the estimates obtained by the two types of clamp. Cell size is also shown to affect cSEVC performance but not that of dSEVC. The nature and magnitude of errors obtained by using both types of clamp in different situations are discussed.

Amplifiers, Electronic↗
PubMed1994

General toxicology of the new antitussive moguisteine.

Moguisteine (R,S(+/-)-2-(2-methoxyphenoxy)-methyl-3-ethoxycarbonylacetyl- 1,3-thiazolidine, CAS 119637-67-1), a new oral non-narcotic peripherally acting antitussive drug, was submitted to toxicological evaluation. The oral (gavage) and intraperitoneal routes in mice and rats and the oral route in rabbits produce very low acute toxicity. Administered by oral route, moguisteine proved to be well tolerated for 26 consecutive weeks and did not induce any general or local effect at up to the respective doses of 240 and 60 mg/kg/day for rats and dogs. In oral (dietary) carcinogenicity studies, moguisteine did not exhibit any carcinogenic effect in mice and rats treated for 87 and 104 weeks, respectively, at up to the dose of 600 mg/kg/day. These results are supported by the absence, both in vitro and in vivo, of mutagenic potential. Considering the overall results of the toxicological studies, it can be affirmed that moguisteine enjoys reliable tolerability, as also shown by a wide safety margin calculated on the basis of the animal and human exposures.

Animals↗
PubMed1993

State of the foreign gene and of the genome in transgenic rice (Oryza sativa L.).

PCR with random primers (RAPD analysis) performed on the DNA of embryogenic and non-embryogenic suspension cultured rice and of transformed rice plants allows the evaluation of the extent of DNA changes in the different biological materials. This is thus suggested as a convenient approach, in combination with restriction analysis and Southerns blotting, to evaluate the integrity of the foreign gene, the stability of the insertion site and the stability of the whole genome.

Base Sequence↗
PubMed1992

Leiomyosarcoma in ectopic areola.

We report an exceptional case of smooth muscle tumor arising in an aberrant areola. In spite of the malignant histopathologic features of the tumor, the patient is healthy 6 years after complete surgical removal of his lesion.

Breast Neoplasms↗
PubMed1991

Activation kinetics of calcium currents in bull-frog sympathetic neurones.

1. Calcium currents were recorded in dissociated bull-frog sympathetic neurones (BSNs) through patch pipettes using discontinuous voltage clamp. Activation kinetics were examined by analysing turn-on and turn-off currents. 2. After short depolarizing pulses turn-off tail currents were fitted with the sum of two exponentials. The fast component (time constant, tau approximately 240 microseconds at -40 mV) was undoubtedly due to the closure of calcium channels. The significance of a small and slower component is discussed. 3. Neither activation nor deactivation time courses changed as channels inactivated during progressively longer pulses or when the holding potential was less negative. No specific component was selectively suppressed by these manipulations. 4. Steady-state activation of the Ca2+ current was described by the Boltzmann distribution raised to the second power. Currents had an apparent threshold at -30 mV and were half-activated at +5 mV. 5. Calcium current turned on following m2 kinetics throughout the range of activation. The slowest time constant was around 1.2 ms between 0 and +10 mV. Turn-on was faster at negative or more positive potentials. 6. The time course of decay of tail currents became progressively faster at more negative potentials. 7. The instantaneous current-voltages (I-V) curve was obtained from tail current measurements and fitted by a modified constant-field equation. 8. The measured peak I-V curve could be reconstructed from the activation curve and the instantaneous I-V curve. 9. The activation kinetics of the calcium current in BSNs were consistent with the existence of a single kinetic class of channels and can be described with a simple m2 Hodgkin-Huxley model.

Animals↗
PubMed1990

Subcellular calcium transients visualized by confocal microscopy in a voltage-clamped vertebrate neuron.

Confocal laser-scanned microscopy and long-wavelength calcium (Ca2+) indicators were combined to monitor both sustained and rapidly dissipating Ca2+ gradients in voltage-clamped sympathetic neurons isolated from the bullfrog. After a brief activation of voltage-dependent Ca2+ channels, Ca2+ spreads inwardly, and reaches the center of these spherical cells in about 300 milliseconds. Although the Ca2+ redistribution in the bulk of the cytosol could be accounted for with a radial diffusion model, local nonlinearities, suggesting either nonuniform Ca2+ entry or spatial buffering, could be seen. After electrical stimulation, Ca2+ signals in the nucleus were consistently larger and decayed more slowly than those in the cytosol. A similar behavior was observed when release of intracellular Ca2+ was induced by caffeine, suggesting that in both cases large responses originate from Ca2+ release sites near or within the nucleus. These results are consistent with an amplification mechanism involving Ca2(+)-induced Ca2+ release, which could be relevant to activity-dependent, Ca2(+)-regulated nuclear events.

Animals↗
PubMed1990

A repeated chromosomal DNA sequence is amplified as a circular extrachromosomal molecule in rice (Oryza sativa L.).

The plasmid pE10 is a pBR322-derived plasmid carrying a 4.5 kb rice (Oryza sativa L.) repeated DNA sequence. The cloned sequence has been shown to be amplified in cultured rice cells. The analysis of practically intact chromosomal rice DNA molecules by pulsed field gel electrophoresis has now shown that the amplification is associated with the appearance of extrachromosomal molecules. In fact, pE10 hybridizes exclusively with unfractionated DNA from leaf protoplasts, while it recognizes predominantly an extrachromosomal DNA molecule (ECD) of about 45 kb and its multiples in the case of protoplasts from cultured cells. Insensitivity to the action of the exonuclease Bal31 suggests that the molecule is circular. Analysis of restriction endonuclease products with both standard horizontal and pulsed field gel electrophoresis suggest that the extrachromosomal DNA, and its chromosomal counterpart, is composed of tandemly repeated units of about 7 kb. Thus, the smaller extrachromosomal circle should contain 6-7 repeats, while the sequence cloned in pE10 is a subset of this repeat. The extrachromosomal DNA represents about 1% of total rice DNA and its level of amplification is not affected by the different phases of growth in culture.

Cells, Cultured↗
PubMed1990

Calcium diffusion modeling in a spherical neuron. Relevance of buffering properties.

We have developed a calcium diffusion model for a spherical neuron which incorporates calcium influx and extrusion through the plasma membrane as well as three calcium buffer systems with different capacities, mobilities, and kinetics. The model allows us to calculate the concentration of any of the species involved at all locations in the cell and can be used to account for experimental data obtained with high-speed Ca imaging techniques. The influence of several factors on the Ca2+ transients is studied. The relationship between peak [Ca2+]i and calcium load is shown to be nonlinear and to depend on buffer characteristics. The time course of the Ca2+ signals is also shown to be dependent on buffer properties. In particular, buffer mobility strongly determines the size and time course of Ca2+ signals in the cell interior. The model predicts that the presence of exogenous buffer, such as fura-2, modifies the Ca2+ transients to a variable extent depending on its proportion relative to the natural, intrinsic buffers. The conclusions about natural calcium buffer properties that can be derived from Ca imaging experiments are discussed.

Animals↗
PubMed1990

[Structural and ultrastructural study of an isolated case of pili annulati].

A case of pili annulati in an eighteen year old woman is described. The hairs show bright spots along hair shafts when viewed in daylight. The transmission and scanning electron microscopy confirmed that the bright spots are due to small cavities into the cortex. The plasmatic measurement of copper, zinc and of the most important hormone, such as the dosage of plasmatic, urinary and hair aminoacids, allowed the Authors to exclude any influence of metabolic systemic alterations on the pathogenesis of pili annulati. Neither cutaneous nor internal anomalies were detected.

Adolescent↗
PubMed1989

Protective effect of reduced glutathione against cisplatin-induced renal and systemic toxicity and its influence on the therapeutic activity of the antitumor drug.

Reduced glutathione has been shown to be an effective protector against cisplatin-induced nephrotoxicity of potential clinical value, since it does not reduce antitumor activity of the cytotoxic drug. This paper extends previous observations on the protective potential of reduced glutathione against cisplatin-induced nephrotoxicity, in different rodent models. Following i.v. administration, glutathione protection against cisplatin-induced nephrotoxicity was found to be critically dependent on timing of thiol administration. Whereas the sulfhydryl compound provided almost complete protection in CD rats, the protective effect against toxic renal damage was only partial in mice of different strains. In spite of the modest protection against kidney toxicity, glutathione reduced lethal toxicity in the mouse. Under the same experimental conditions at protective dose levels, the tripeptide thiol did not interfere with the antitumor effectiveness of cisplatin, in any of the tumor models examined. The kidney content of non-protein sulfhydryls of CD rats produced by the effective dose of glutathione was markedly higher than that found in the mouse treated with the same dose. This finding is consistent with a differential protection provided by glutathione against cisplatin-induced renal toxicity in these species.

Animals↗
PubMed1989

[Hand-foot-mouth disease: its course in the city of Milan (1980-86). Epidemiologic study gathered from the records of the community and scholastic ambulatory services of the Istituto di Clinica Dermatologic I and Dermatologia Pediatrica of the University].

Hand-foot-mouth disease: the Authors describe the epidemiological observations in a period of seven years made in a big urban area of Milan. They point out the periodic course of hand-foot and mouth disease, which is present in particular during May and November and particularly in children under six years. The Authors point out the difference between males and females and they try to correlate their dates with those gathered from the study of the literature.

Adolescent↗
PubMed1988

Self-healing pseudoangiosarcoma. Unusual vascular proliferation resembling a vascular malignancy of the skin.

Pseudomalignant vascular lesions are increasingly recognized by dermatologists and may be present in several disorders affecting vessels. We describe a 58-year-old obese woman who developed vascular papulonodular lesions in the left inguinocrural area, clinically and histologically resembling a malignant vascular proliferation, that spontaneously regressed within a few months, after bed rest and weight reduction. Therefore, our patient's vascular lesions appear to have been pseudomalignancies. There are no other similar conditions reported in the literature. This kind of disorder demonstrates that vascular tissue can be involved in very bizarre cell and tissue reactions to several stimuli and can mimic malignant neoplasms. We stress the importance of constant surveillance of this kind of lesion to collect adequate clinical data, because histologic findings alone may cause misdiagnosis and lead to treatment hazardous to the patient.

Diagnosis, Differential↗
PubMed1988

Cutaneous metastases from laryngeal carcinoma.

The authors describe a case of cutaneous metastases from a squamous cell carcinoma of the laryngeal vestibule. The skin lesions, which consisted of nodules localized to the forehead and left arm, appeared 2 years after diagnosis of the primary tumor. The skin manifestations preceded lung metastases by 5 months.

Carcinoma, Squamous Cell↗