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Biomedical subjects

F Conti

Publications and source records attributed to F Conti.

At least 253 records · Page 14Linked to original sources
PubMed1978

[Surgical complications of pacemaker implantation (author's transl)].

During the period 1966-1977, 705 pacemaker implantations with transvenous endocardial electrode and 369 substitutions of generators were carried out, besides 275 operations treating some complications after implantation were required. The most frequent complications were: endocardial electrode dislocation (9.4%), lesion caused by decubitus (7.5%) and infection of subcutaneous pocket (5%), decubitus lesion and infection of the skin caused by the electrode (1.7%), electrode and generator breaking (1.3%), right ventricle perforation caused by the electrode (0.37%). Surgical mortality-rate was 0.18%.

Adult↗
PubMed1977

An electron paramagnetic resonance study of free radicals in cells.

An electron paramagnetic resonance study was performed on cell lines of the following strains: HeLa, 37RC, L, FLC, NRK/RSV, 3T3/SV40. Unsynchronized and synchronized HeLa cells were studied with particular attention paid to the relation between growth and free radical concentration. Free radical levels were shown to be a function of the growth stage and different phases of the cell cycle.

Cell Division↗
PubMed1977

Soybean-protein diet in the treatment of type-II hyperlipoproteinaemia.

A soybean textured protein induced a 14% decrease of plasma-cholesterol levels after two weeks and 21% after three when substituted for animal proteins in a group of 20 patients with type-II hyperlipoproteinaemia. Comparison of soybean diet with a standard low-lipid diet in the same patients, according to a cross-over protocol, indicated that this hypocholesterolaemic effect was not due to differences in the lipid composition of the two diets. The hypothesis that a soy protein has a hypocholesterolaemic action per se is supported by the results of a subsequent experiment in 8 type-II patients in whom the addition of cholesterol (500 mg/day) to soy protein did not modify the hypocholesterolaemic response.

Adult↗
PubMed1977

Increased pulmonary residual volume in patients with hyperlipoproteinemias.

A syndrome, characterized by pulmonary hyperdistension (increased residual volume, closing capacity and Motley index), was observed in patients with hyperlipoproteinemias without without other known causes of pulmonary disease. This syndrome is mostly asymptomatic;hyperdistension is of variable degree and not directly correlated to plasma lipid levels. It is partially reversible after reduction of lipidemia. The cause of this syndrome is not known. It may explain a decreased pulmonary working capacity in asymptomatic hyperlipidemic patients.

Adult↗
PubMed1977

Treatment of hypertriglyceridemia with metformin. Effectiveness and analỳsis of results.

The triglyceride-lowering effect of metformin (N,N-dimethylbiguanide) was tested in a series of patients with stable hypertriglyceridemia (types IIB, III and IV) and with variable degrees of glucose intolerance. Metformin caused a 38% mean decrease of plasma triglycerides. A selective decrease of very low density lipoprotein cholesterol was observed without reciprocal increase of low density lipoproteins. Thirty patients completed the study. Eighteen, who showed a hypotriglyceridemic effect exceeding 30%, were considered as "Responders"; the other 12, where the effect was negligible, were considered as "Non-Responder". Analysis of the pre-and post-treatment glucose tolerance tests of Responders and Non-Responders showed that the former had, on the average, a normal glucose tolerance and insulin secretion, whereas the latter had an impaired glucose tolerance with increased insulin secretion. These parameters were only slightly modified by metformin. The conclusions of this study support the hypothesis that biguanides exert a triglyceride-lowering effect by decreasing lipoprotein secretion, independent of changes in glucose tolerance and/or insulin secretion.

Adult↗
PubMed1976

Measurement of the conductance of the sodium channel from current fluctuations at the node of Ranvier.

Single myelinated nerve fibres of Rana esculenta were investigated under voltage clamp conditions at 13 degrees C. Fluctuations of steady-state membrane current were measured during the last 152 msec of 190-225 msec pulses depolarizing the membrane by 8-48 mV. Noise power spectral densities were calculated in the frequency range of 6-6-6757 Hz. 2. External application of 150 nM tetrodotoxin (TTX) and/or 10 mM tetraethylammonium (TEA) ion reduced the current fluctuations. The difference of current noise spectra measured in the presence and absence of TTX (TEA) was not changed by the presence of TEA (TTX) during both measurements, and was taken as the spectrum of the Na (K) current fluctuations. 3. Residual current noise during application of both TTX and TEA was, except for some excess noise at the low and high frequency ends of the spectrum, similar to the noise measured from a passive nerve model and could be understood in terms of Nyquist noise of the known resistances and the amplifier noise. 4. Na current fluctuation spectra were interpreted as the sum N/f+SNa(f) where SNa(F) represents the spectrum expected for a set of equal, independent Na channels with only two conductance states (open or closed) which follow Hodgkin-Huxley kinetics. With values of hinfinity, tauh and minfinity measured from macroscopic Na currents, the measured spectra were fitted well by optimizing N, SNa(0) and taum. Values of taum obtained by this method were in fair agreement with values found from macroscopic currents. 5. The 1/f component of Na current noise was roughly proportional to the square of the steady-state Na current, I2. The mean value of N/I2 was (1-1 +/- 0-3) X 10(-4). 6. The current carried by a single Na channel was calculated from fitted spectra and steady-state Na currents measured simultaneously with the current fluctuations. The single channel conductance gamma normalized to zero absolute membrane potential was calculated. The average gamma from twelve measurements at depolarizations of 8-40 mV was 7-9 +/- 0-9 pS (S.E. of mean). The apparent value of gamma was smallest with small depolarizations. Variations of the assumed kinetic properties of the model did not drastically affect the single channel conductance. 7. External application of 0-1 mM-Ni ion lengthened taum in the macroscopic currents and in the fluctuation spectra and enhanced both the steady-state Na current and the current fluctuations. In Ni-treated nodes gamma was smaller than in normal nodes.

Animals↗
PubMed1976

Conductance of the sodium channel in myelinated nerve fibres with modified sodium inactivation.

1. Na current fluctuations in nodes of Ranvier were measured under voltage clamp conditions as described in the preceding paper (Conti, Hille, Neumcke, Nonner & Stämpfli, 1976) and analysed in terms of power spectral density calculated for frequencies between 30 Hz and 5 kHz. 2. External (10(-5) g/ml.) Leiurus scorpion venom or Anemonia Toxin II (3 X 10(-5) g/ml.) or internal 20 mM iodate were applied in order to remove or slow down inactivation in part of the Na channels. The treatment increased the steady-state Na current during the noise measurement one-to eight fold over that in normal fibres. 3. Noise spectra were interpreted as the sum of 1/f noise and noise SNa(f) due to all-or-none, open-close transitions of single Na channels. The drug effects on the inactivation could be accounted for either by assuming two populations of channels, one with and one without inactivation, or by postulating a single population with modified inactivation characteristics. 4. Except for an increase in amplitude, the fluctuation spectra SNa(f) were similar to the ones in normal nodes. Again, the time constants taum obtained from the fit of the spectra agreed within a factor of 2 with the values of taum found in the macroscopic Na currents. 5. From the fluctuation spectra, single Na channel conductances gamma of 5-4 +/- 0-4 pS (iodate), 6-7 +/- 0-5 pS (Leiurus) and 7-0 +/- 0-6 pS (Anemonia) were calculated. The value of gamma was not significantly voltage dependent. 6. Our observations indicate that inactivation of Na channels can be modified with at most small effects on the microscopic properties of the activation process and on the conductance of the open channel. They suggest that the h mechanism normally produces all-or-none, open-close changes of conductance.

Animals↗
PubMed1975

Fluorescence polarization studies of squid giant axons stained with N-methylanilinonaphthalenesulfonates.

The polarized components of the extrinsic fluorescence of squid giant axons stained with 2,6-MANS or 1,8-MANS were studied. The polarization properties of the fluorescence changes associated with voltage-clamp pulses were found to be very different from those of the static fluorescence, supporting the notion that the optical changes involve highly oriented membrane adsorbed fluorophores. The theoretical expectations according to this hypothesis are discussed in detail. The experimental results are in good agreement with the theory assuming that possible probes reorientations are soley due to the action of the applied electric field upon the probes electric dipole. The quantitative analysis of the data for 2,6-MANS provides a fairly accurate determination of the orientation of the membrane bound 2,6-MANS molecules responsible for the fluorescence changes. Such orientation appears to be independent of the membrane face exposed to staining. The data for 1,8-MANS indicate a very different orientation of this isomer. The results suggest a profitable use of extrinsic fluorophores for studies of the structural organization of nerve membranes.

Anilino Naphthalenesulfonates↗
PubMed1975

Double-blind study of the analgesic effect of indoprofen (K 4277).

In a double-blind study, indoprofen was superior to placebo in decreasing pain in patients with primary and metastatic cancer and with neuralgia. A single oral dose of 200 mg was more active than a 100-mg dose. The preferences of patients proved to be a more sensitive parameter in this study than scores of pain intensity, pain relief, and other related measurements (SPID, TOTPAR, and Peak PID).

Adult↗
PubMed1975

Potassium and sodium ion current noise in the membrane of the squid giant axon.

1. The spectral density of current noise power from 20 mm segments of giant axons of the squid Loligo vulgaris has been measured under space-clamp and voltage-clamp conditions. From 4 to 1000 Hz the measured noise is larger by several orders of magnitude than the theoretical thermal noise. The amplifier's noise, which may yield appreciable contributions above 200 Hz, could be evaluated and subtracted from the total noise using direct measurements of the membrane impedance...

Action Potentials↗