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Biomedical subjects

F Bruni

Publications and source records attributed to F Bruni.

At least 73 records · Page 4Linked to original sources
PubMed1989

Dielectric properties of Artemia cysts at low water contents. Evidence for a percolative transition.

Cellular cysts of the crustacean Artemia provide a useful model for studies on water-dependent mechanisms in cellular function because they can undergo reversible cycles of dehydration-rehydration. We explored their dielectric behavior over the frequency range of 10 kHz to 1 MHz, at water contents between near zero and 0.5 g H2O/g dry weight (g/g). The dc conductivity and static dielectric permittivity were evaluated from electrostatic analysis of data obtained with a three-layered capacitor. Below cyst hydrations of 0.05 g/g, negligible dielectric response was observed at all frequencies. Between 0.05 and 0.25 g/g the permittivity increased sharply then reached a near plateau up to cyst hydrations close to 0.35 g/g, above which a second abrupt increase occurred. Values for the dielectric loss (tan delta) exhibited frequency-dependent peaks over the hydration range of 0.05-0.3 g/g, followed by an abrupt increase near 0.35 g/g, an hydration at which metabolism is first initiated in this system. These hydration-dependent dielectric changes are compared with previous studies on the biology and physics of this system, and evaluated by a model involving percolative ionic (likely protonic) conduction. Percolative behavior is characterized by a sharp increase in conductivity at a critical threshold of hydration (hc) according to a power law in which the exponent, t, equals 1.65 for a three-dimensional infinite lattice. For the Artemia cyst, t = 1.64 above hc = 0.35 g/g, which is in excellent agreement with theory. These results are compared to similar studies on lysozyme which also exhibits percolative behavior connected with the onset of biological function.

Animals↗
PubMed1988

Two-dimensional protonic percolation on lightly hydrated purple membrane.

The capacitance and dielectric loss factor were measured for a sample of purple membrane of Halobacterium halobium as a function of hydration level (0.017 to >0.2 g of water/g of membrane) and frequency (10 kHz to 10 MHz). The capacitance and the derived conductivity show explosive growth above a threshold hydration level, h(c) approximately 0.0456. The conductivity shows a deuterium isotope effect, H/(2)H = 1.38, in close agreement with expectation for a protonic process. The level h(c) is frequency independent and shows no deuterium isotope effect. These properties are analogous to those found for lysozyme in a related study. Protonic conduction for the purple membrane can be considered, as for lysozyme, within the framework of a percolation model. The critical exponent, t, which describes the conductivity of a percolative system near the threshold, has the value 1.23. This number is in close agreement with expectation from theory for a two-dimensional percolative process. The dielectric properties of the purple membrane are more complex than those of lysozyme, seen in the value of h(c) and in the frequency and hydration dependence of the loss factor. There appear to be preferred regions of proton conduction. The percolation model is based upon stochastic behavior of a system partially populated with conducting elements. This model suggests that ion transport in membranes and its control can be based on pathways formed of randomly connected conducting elements and that a fixed geometry (a proton wire) is not the only possible basis for a mechanism of conduction.

Journal Article↗
PubMed1987

Synthesis of some 7-phenylpyrrolo[1,2-a]pyrimidine derivatives. III.

2-Amino-4-phenylpyrrolyl-3-carbonitrile (I) was reacted with ethyl formylacetate sodium salt affording 1,4-dihydro-4-oxo-7-phenylpyrolo[1,2-a]pyrimidin-8-carbonitrile (II), which was alkylated with EtI to give (III), which in turn was hydrolyzed to (IV). Treatment of both (III) and (IV) with 99% H3PO4 at approximately 200 degrees gave 1,4-dihydro-1-ethyl-7-phenylpyrrolo-[1,2-a]pyrimidin-4-one (V) whose structure was ascertained by an unequivocal synthesis starting from (I) and diethyl ethoxymethylenmalonate. Compound (V) was prepared in order to test its pharmacological properties in comparison with 4,7-dihydro-4-ethyl-2-phenylpyrazolo[1,5-a]pyrimidin-7-one, which showed an antiinflammatory activity comparable to that of phenylbutazone and indomethacine, and which was found devoid of ulcerogenic properties.

Animals↗
PubMed1987

Pharmacological activity of some pyrrolo and pyrazolo pyrimidine derivatives.

4,7-Dihydro-4-ethyl-2-phenylpyrazolo-[1,5-a]pyrimidin-7-one (FPP028) is the prototype of a class of pyrazolo[1,5-a]pirimidine derivatives that has been shown to possess marked antiinflammatory and analgesic properties; 1,4-dihydro-1-ethyl-7-phenylpyrrolo[1,2-a]pyrimidin-4-one (FPP129) is a new compound belonging to a series of pyrrolo[1,2-a]pirimidine derivatives that has been synthetized in an attempt to reduce certain toxic effects observed with FPP028. To evaluate these two compounds more fully, in the present study we determined the LD50 of FPP129 in mice and assessed its activity in different experimental inflammation models. Ulcerogenic properties of FPP129 were evaluated by the test of stress-induced ulcer in rats. We also studied the in vitro and ex vivo effects of both FPP028 and FPP129 in a series of platelet-aggregation experiments using either arachidonate or collagen as aggregating agents. In the carraggeenan-induced paw edema, FPP129 exerted a marked anti-inflammatory activity with an ED50 of 22.2 mg/kg. FPP129 inhibited also the edema induced by concanavalin-A or Paf-acether. The in vitro anti-aggregatory activity of FPP028 was shown to be much less than that of indomethacin, thus confirming the hypothesis that the compound is a very weak inhibitor of cyclooxygenase. Ex vivo, both FPP028 and FPP129 were shown to exert no antiaggregatory effect in rabbits after administration of doses equal to the ED50. No ulcerogenic activity was found with FPP129, this result being consistent with previous observations on FPP028. Our data show tha FPP028 and FPP129 do not share a typical mechanism of action (cyclooxygenase inhibition) found with the majority of nonsteroidal antiinflammatory drugs. Nonetheless, the antiinflammatory properties of these compounds, together with their lack of ulcerogenic activity, indicate that both FPP028 and FPP129 are potentially interesting for future therapeutic use.

Animals↗
PubMed1986

Biofiltration with buffer-free dialysate.

The presence of acetate in the dialysate appears to be superfluous in the new depurative technique indicated as biofiltration, which consists in a standard hemodialysis with high ultrafiltration combined with the reinfusion of 3-4 1/2 liters of solution containing bicarbonate. The presence of acetate could in fact be contraindicated by a number of potential side effects, metabolic, cardiovascular and biological. Hence, starting from the consideration that in standard biofiltration a buffer is already infused directly as bicarbonate, we tried to overcome the potential hazards of the acetate-containing bath simply by using a dialysate without acetate and by increasing the concentration of bicarbonate in the reinfusate. A cumulative clinical experience of 20 months in 4 patients proved the feasibility and safety of the technique and suggests further advantages over standard biofiltration (better control of acid-base equilibrium, better cardiovascular stability.

Acetates↗
PubMed1986

[Some derivatives of the 2-[4-pyrazolinyl]-1,3,4-thiadiazole system].

The synthesis of some 2-[5-amino-1-methyl-3-oxo-4-pyrazolynyl]-1,3,4-thiadiazole derivatives is accomplished by reacting 5-amino-1-methyl-3-oxopryrazolynyl-4-dithiocarbohydrazide with carboxylic acid derivatives. The structure of the compounds obtained is verified by means of 1H and 13C-N.M.R. spectra. Antimicrobial and antifungal activity of some of the described compounds was tested in a preliminary screening.

Anti-Infective Agents↗
PubMed1983

2-Phenylpyrazolo[1,5-a]pyrimidin-7-ones. A new class of nonsteroidal antiinflammatory drugs devoid of ulcerogenic activity.

Syntheses of some pyrazolo[1,5-a]pyrimidines were performed in order to study the relationship between structural modifications on the parent 4,7-dihydro-2-phenylpyrazolo[1,5-a]pyrimidin-7-one (1) and their antiinflammatory properties. The modifications carried out were introduction and functionalization of a longer side chain at the 4-position, substitution of the hydrogen atom at the 3-position, and replacement of the phenyl group with a 4-methylphenyl, methyl, or hydrogen substituent. 4-Ethyl-4,7-dihydro-2-phenylpyrazolo [1,5-a]pyrimidin-7-one (3) showed the highest activity and a better therapeutic index than phenylbutazone and indomethacin, used as reference drugs. All other changes at the 3-, 5-, and 6-positions, as well as the replacement of the phenyl group at position 2, caused a marked decrease of activity. Compound 3 was found devoid of ulcerogenic activity and was probably endowed with antiulcerogenic properties.

Animals↗
PubMed1981

New pharmacologically active 2-phenylpyrazolo [1,5-a]pyrimidines.

2-Phenylpryrazolo [1,5-a]pyrimidine (I) 4,7-dihydro-2-phenylpyrazolo [1,5-a]pyrimidin-7-one (II) and 4,5-dihydro-2-phenylpyrazolo [1,5-a]pyrimidin-5-one (III) are prepared. Because of the interesting antipyretic, hypothermizing and anti-inflammatory properties of some of their derivatives, the above mentioned compounds are used as reference compounds in a Q.S.A.R. study still in progress. Methylation of (II) and (III) with (CH3)2SO4 and CH2N2 gives methylderivatives whose structure is determined by spectroscopic means.

Animals↗
PubMed1979

[Structure and antipyretic-hypothermizing effect of various pyrazol/1,5-a/pyrimidines].

Structures of condensation products between 3-phenyl-5-aminopyrazole and ethyl ethoxymethylenacetoacetate and ethyl acetonoxalate are demonstrated, namely ethyl 2-phenyl-7-methylpyrazolo[1,5-a]pyrimidin-6-carboxylate and ethyl 2-phenyl-7-methylpyrazolo[1,5-a]pyrimidin-5-carboxylate. Studies on antipyretic and hypothermizing activity of the acid derived from the latter and of other compounds are reported.

Animals↗
PubMed1979

[Condensation of 3-phenyl-5-aminopyrazolo with acylpyruvic and ethoxymethylenacetic esters].

The synthesis of ethyl 2-phenyl-7-alkyl (or 7-phenyl)pyrazolo[1,5-a]pyrimidine-5-carboxylate and ethyl 2-phenyl-7-alkyl (or 7-phenyl)pyrazolo[1.5-a]pyrimidine-6-carboxylate are reported. Decarboxylation of the acids, obtained by hydrolysis of the above esters, yields the same compounds. N.M.R. data on the reduction products of the ethyl 6-carboxylate confirm all the assigned structures.

Acetates↗
PubMed1979

[Introduction to the use of 125 iodine in interstitial radiotherapy (author's transl)].

The 125-iodine is employed for definitive implantation in the treatment of some apical and non apical lung tumors, and in pancreas and prostate tumors. The results obtained by the authors are not evaluable and the results of north-american literature are reported. The 125-iodine properties are original and allows a very important progress above all of the protection problems.

Brachytherapy↗
PubMed1978

Structure of pyrazolo[1,5-a]pyrimidine methylderivatives.

In the course of researches on pyrazolo[1,5-a]pyrimidine compounds, methylation reactions with (CH3)2SO4 and CH2N2 are studied. Methylderivatives structure is assigned by means of a spectroscopic investigation. A relationship between the kind of reagent and the methyl group position is stressed.

Chemical Phenomena↗
PubMed1978

[Pyrazolo[3,4d][1,3]thiazine systems].

The synthesis of 1,2,4,6-tetrahydro-2-methyl-3-hydroxypyrazolo [3,4-d] [1,3]thiazine-4,6-dithione is described. By spectroscopic methods the anphionic structure of this and other related compounds is demonstrated. In addition, the action of alkylating reagents upon pyrazolo-[3,4-d] [1,3]thiazine-4,6-dithionic compounds is examined and described. The biological activity of the new synthesized compounds is reported.

Animals↗