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Biomedical subjects

E Ragazzi

Publications and source records attributed to E Ragazzi.

At least 19 recordsLinked to original sources
PubMed2006

Metabolomic fingerprinting of plant extracts.

The standardization and quality control of plant extracts is an important topic, in particular, when such extracts are used for medicinal purposes. Consequently, the development of fast and effective analytical methods for metabolomic fingerprinting of plant extracts is of high interest. In this investigation, electrospray mass spectrometry (ESI-MS) and (1)H NMR techniques were employed with further statistical analyses of the acquired data. The results showed that negative ion mode ESI-MS is particularly effective for characterization of plant extracts. Different samples of the same species appear well-clustered and separated from the other species. To verify the effectiveness of the method, two other batches of extracts from a species, in which the principal components were already identified (Cynara scolymus), were analyzed, and the components that were verified by the principal component analysis (PCA) were found to be within the region identified as characteristic of Cynara Scolymus extracts. The data from extracts of the other species were well separated from those pertaining to the species previously characterized. Only the case of a species that was strictly correlated from a botanical point of view, with extracts that were previously analyzed, showed overlapping.

Achillea↗
PubMed2005

A matrix-assisted laser desorption/ionization mass spectrometry study of the non-enzymatic glycation products of human globins in diabetes.

The molecular species present in globins from healthy and diabetic subjects with and without chronic complications have been analyzed by matrix-assisted laser desorption/ionization mass spectrometry. The technique demonstrated the presence of glycated and glyco-oxidated species of both alpha- and beta-globins. Their abundances show a good linear relationship with respect to HbA1c values and with the mean daily plasma glucose levels over the 6 weeks preceding the investigation. Interestingly, slightly different behaviour is observed in the data from patients with and without chronic complications; the plots of HbA1c vs. the abundance of glycated and glyco-oxidated species show different slopes and different intercepts with the y-axis. To investigate this aspect the mean abundances of glyco-oxidated species from healthy subjects and from diabetic patients with and without complications were calculated. Higher values were found for the two last sets of samples, but no significant difference was found between them. These data could indicate different individual proclivities to oxidation and/or different oxidation kinetics related to behavioural and environmental factors.

Aged↗
PubMed2005

Evaluation of glyoxal and methylglyoxal levels in uremic patients under peritoneal dialysis.

Advanced glycation end products (AGEs) accumulate in serum and tissues of patients with chronic renal failure, even in the absence of diabetes, and a different clearance of these species has been observed by hemodialysis and peritoneal dialysis (CAPD). Furthermore, it has been shown that not only AGE but also 1,2-dicarbonyl compounds are formed during heat sterilization of glucose-based peritoneal dialysis fluids. Therefore, we investigated the level of some AGEs (pentosidine and free pentosidine) and dicarbonyl compounds (glyoxal and methylglyoxal) in end-stage renal disease patients subjected to peritoneal dialysis. Samples (20 from healthy subjects, 16 from uremic patients before and after 12 h of peritoneal dialysis) were analyzed, and the plasma and dialysate levels of glyoxal, methylglyoxal, pentosidine, and free pentosidine were determined. In plasma of uremic patients, mean values of pentosidine showed a small decrease after dialysis and were always higher than those of healthy control subjects. An analogous trend was observed for free pentosidine. In the case of peritoneal dialysate, no pentosidine and free pentosidine were found at time zero, whereas both compounds were detected after 12 h of dialysis. Glyoxal and methylglyoxal mean levels showed a decrease in plasma after dialysis even if their values were always higher than those of healthy control subjects. Surprisingly, an analogous trend was observed also in dialysate. These results might indicate that glyoxal and methylglyoxal already present in the dialysis fluid react with the peritoneal matrix proteins, accounting for the gradual loss of peritoneal membrane function that is often observed in patients subjected to CAPD for a long time.

Aged↗
PubMed2005

The "bubble point" for validation of drug release or simulated absorption tests for ointments.

The aim of the present study was to design a test to ascertain the behaviour and reliability of a membrane used in drug release and simulated absorption tests in order to arrive at useful indications for simulating topical as well as gastro-intestinal absorption. The membrane can be used in two different conditions: a) as a simple porous membrane placed between the ointment and an accepting liquid phase, generally water phase; b) as a membrane soaked in a lipophilic liquid phase to simulate the horny layer between the ointment and accepting water phase. In this study the "bubble point test" was used to test the integrity of the soaking film as well as the membrane, during and after drug release and simulated absorption tests with different types of ointment. In the case of a drug release test from an ointment, the bubble point test may determine the test conditions, that is the ointment applied to either a dry or hydrated membrane. Only the use of a previously hydrated membrane can guarantee constant conditions in the in vitro model. Use of a dry membrane may lead to infiltration of liquid components of the ointment base, thus altering the contact conditions between the two phases of the cutaneous compartment model (lipogel and W/O creams). The use of a hydrated membrane may also lead to interactions between the two phases of the compartment, with osmotic exchanges between the acceptor phase and ointment sample (hydrogel, PEG gel, O/W creams). The hydrated membrane is therefore reliable only for comparison between lipophilic base ointments. In a simulated absorption test, determination of the bubble point makes it possible to ascertain the physical integrity of the lipoid liquid film immobilized by capillary action in the inner microporous structure of the membrane during the test. This condition is essential to maintain a balance between the parameters regulating the diffusion process between the different compartments of the system. The use of a lipoid-soaked membrane makes it possible to avoid interactions between the ointment sample and an aqueous acceptor phase, such as hydrosoluble bases. Since the diffusion across a lipoid film immobilised within a porous membrane depends on the drug release rate from the ointment base, the test allows a contextual evaluation of the release kinetics as well as an indication of the drug absorption possibilities through an in vitro model of the cutaneous compartment.

Algorithms↗
PubMed2004

The complexity of non-enzymatic glycation product sets of human globins.

AIMS/HYPOTHESIS: Recently an individual variability in the relationships between mean blood glucose levels and HbA1c has been observed among diabetic patients. The aim of this study was to provide an accurate description and evaluation of glycated and glyco-oxidated globins from diabetic subjects and their relationship with HbA1c and plasma glucose values. METHODS: We studied 20 type 2 diabetic and 10 healthy subjects. Plasma samples were analysed by matrix-assisted laser desorption ionisation mass spectrometry. RESULTS: The presence of glycated and glyco-oxidated species of both alpha and beta globin was demonstrated. Values for these showed a good linear relationship with HbA1c values and the mean daily plasma glucose values for the 6 weeks preceding the investigation. Trends differed according to whether patients had chronic complications or not, differences being seen in the slopes of the plots relating HbA1c to the abundance of glycated and glyco-oxidated species. CONCLUSIONS/INTERPRETATION: The data obtained are consistent with the concept that individuals have a different individual proclivity for oxidation and/or that different oxidation kinetics are related to behavioural and environmental factors. Our data are thus relevant to the analysis of phenotype differences in diabetic patients.

Aged↗
PubMed2001

Enzyme activities involved in tryptophan metabolism along the kynurenine pathway in rabbits.

The following enzyme activities of the tryptophan-nicotinic acid pathway were studied in male New Zealand rabbits: liver tryptophan 2,3-dioxygenase, intestine indole 2,3-dioxygenase, liver and kidney kynurenine 3-monooxygenase, kynureninase, kynurenine-oxoglutarate transaminase, 3-hydroxyanthranilate 3,4-dioxygenase, and aminocarboxymuconate-semialdehyde decarboxylase. Intestine superoxide dismutase and serum tryptophan were also determined. Liver tryptophan 2,3-dioxygenase exists only as holoenzyme, but intestine indole 2,3-dioxygenase is very active and can be considered the key enzyme which determines how much tryptophan enters the kynurenine pathway also under physiological conditions. The elevated activity of indole 2,3-dioxygenase in the rabbit intestine could be related to the low activity of superoxide dismutase found in intestine. Kynurenine 3-monooxygenase appeared more active than kynurenine-oxoglutarate transaminase and kynureninase, suggesting that perhaps a major portion of kynurenine available from tryptophan may be metabolized to give 3-hydroxyanthranilic acid, the precursor of nicotinic acid. In fact, 3-hydroxyanthranilate 3,4-dioxygenase is much more active than the other previous enzymes of the kynurenine pathway. In the rabbit liver 3-hydroxyanthranilate 3,4-dioxygenase and aminocarboxymuconate-semialdehyde decarboxylase show similar activities, but in the kidney 3-hydroxyanthranilate 3,4-dioxygenase activity is almost double. These data suggest that in rabbit tryptophan is mainly metabolized along the kynurenine pathway. Therefore, the rabbit can also be a suitable model for studying tryptophan metabolism in pathological conditions.

3-Hydroxyanthranilate 3,4-Dioxygenase↗
PubMed2001

Do ATP and UTP involve cGMP in positive inotropism on rat atria?

ATP and UTP induced a dual inotropic effect in rat left atria: first a decrease and then an increase in contractile tension were observed. PPADS, an antagonist of P2X receptors, inhibited positive inotropism induced by ATP and alpha,beta-meATP. Chiefly, we investigated intracellular mechanisms responsible for the positive inotropism. We tested cromakalim and glibenclamide, an activator and an inhibitor, respectively, of ATP-sensitive K(+) channels. These compounds did not influence the effects of ATP. IBMX, a phosphodiesterase inhibitor, and H-7, an inhibitor of protein kinase C and cAMP-dependent protein kinase, did not modify the inotropic effects of ATP. Instead, H-8, an inhibitor of cAMP- and cGMP-dependent protein kinases, strongly inhibited the positive effects of both ATP and UTP, suggesting the possible involvement of cGMP in the inotropism. Also, LY 83583, an inhibitor of cGMP production, reduced positive inotropism by alpha,beta-meATP, ATP and UTP. Moreover, 8-Br-cGMP (50 microM), a stable analogue of cGMP, inhibited positive inotropism by all nucleotides. Lastly, we determined intracellular cGMP levels by RIA; the cyclic nucleotide increased during positive inotropism induced by ATP and UTP. The results regarding positive inotropism suggest that: (a) ATP acts through P2X receptors, while UTP may act by P2X, but also through PPADS-insensitive receptors; and (b) changes in intracellular cGMP concentration are involved in this inotropic effect.

Adenosine Triphosphate↗
PubMed2001

Effect of gelling conditions and mechanical treatment on drug availability from a lipogel.

This study has been conducted to determine whether the rheological differences depending on gelling and treatment conditions could have an influence on drug availability. Lipogels with constant composition were obtained by gelling olive oil with monodiglycerides at rest, under stirring, and milled after gelling. The considerable differences in rheological characteristics produced significant differences on in vitro drug release tests, whereas a lesser influence was observed on in vitro simulated absorption test. The rheological differences appeared not to influence in vivo drug availability. Also, rheological differences owing to the concentration of the gelling agent showed no significant influence on in vivo availability.

Absorption↗
PubMed2001

Effect of drug solubility on in vitro availability rate from suppositories with polyethylene glycol excipients.

Factors involved in the availability mechanism of different drugs from suppositories with polyethylene glycol (PEG) excipients were studied using an in vitro model of the rectal compartment with a porous membrane simulating the rectal barrier. Different from lipophilic excipients, the drug is released as a consequence of the progressive dissolution of PEG into the intrarectal aqueous phase. Drug concentration in this small intrarectal phase produces the gradient against the large volume of the plasmatic phase, which regulates the diffusion rate through the barrier. As with lipophilic excipients, drug solubility in water was found to be an important factor influencing suppository release rate. Nevertheless, PEG influenced in vitro drug availability considerably, by increasing both drug solubility and dissolution rate. The osmotic effect of PEG in the intrarectal compartment influenced the increase in volume of the aqueous phase. The results, compared with those obtained from suppositories with a lipophilic excipient, show a higher dissolution rate from PEG excipient, but a higher diffusion rate across the barrier did not always correspond. Drugs less soluble in water showed a greater availability from PEG suppositories. On the contrary the more soluble drugs were less available.

Area Under Curve↗
PubMed2000

Transforming growth factor beta3 inhibits chronic myelogenous leukemia hematopoiesis by inducing Fas-independent apoptosis.

OBJECTIVE: Transforming growth factor beta3 (TGF-beta3) is a potent suppressor of human hematopoietic progenitor cells. In this article, we compare the activity of TGF-beta3 on highly purified CD34+ cells and more immature CD34-DR(-) cells from chronic myelogenous leukemia (CML) patients in chronic phase and normal donors. MATERIALS AND METHODS: Primitive hematopoietic progenitors were stimulated in liquid cultures and clonogenic assays by early-acting growth factors such as stem cell factor (SCF) and interleukin 11 (IL-11) and the intermediate-late-acting stimulating factors IL-3, granulocyte-macrophage colony-stimulating factor, and erythropoietin. Molecular analysis of bcr/abl mRNA was performed on single CML colonies by nested reverse transcriptase polymerase chain reaction. Moreover, cell cycle analysis and assessment of apoptosis of normal and leukemic CD34+ cells were performed by propidium iodide (PI) alone and simultaneous staining with annexin V and PI, respectively. RESULTS: The colony-forming efficiency of CML CD34+ cells was generally inhibited by more than 90% regardless of whether the colony-stimulating factors were used alone or combined. When compared to normal CD34+ cells, leukemic cells were significantly more suppressed in 6 of 8 culture conditions. The inhibitory effect of TGF-beta3 on CD34+ cells was exerted within the first 24 hours of incubation as demonstrated by short-term preincubation followed by IL-3-and SCF-stimulated colony assays. Evaluation of bcr/abl transcript on residual CML colonies incubated with TGF-beta3 demonstrated a small subset of neoplastic CD34+ cells unresponsive to the inhibitory effect of the study cytokine. TGF-beta3 demonstrated a greater inhibitory activity on primitive CD34+DR cells than on more mature CD34+ cells. Again, CML CD34+DR(-) cells were significantly more inhibited by TGF-beta3 than their normal counterparts in 3 of 8 culture conditions. Kinetic analysis performed on CD34+ cells showed that TGF-beta induces cell cycle arrest in G(1) phase. However, this mechanism of action is shared by normal and leukemic cells. Conversely, TGF-beta3 preferentially triggered the programmed cell death of CML CD34-cells without increasing the proportion of leukemic cells coexpressing CD95 (Fas receptor), and this effect was not reversed by functional blockade of Fas receptor. Conclusion. We demonstrate that TGF-beta3 exerts a potent suppressive effect on CML cells that is partly mediated by Fas-independent apoptosis.

Antigens, CD34↗
PubMed2000

Effect of drug solubility on the in vitro availability rate from suppositories with lipophilic excipients.

The factors involved in mechanisms of availability of different drugs from suppositories with lipophilic excipients were studied by using an in vitro model of the rectal compartment with a porous membrane simulating the rectal barrier. The solubility in water of drugs was found to be the fundamental factor influencing the release rate from suppositories. In fact, following the melting of the suppository at body temperature the drug particles can migrate to the interface with the small volume of rectal secretion where they dissolve. Drug molecules can so diffuse until they come into contact with the rectal barrier through which the drug is absorbed. Drug concentration in the intrarectal aqueous phase produces the gradient against the large volume of the plasma phase. This gradient regulates the diffusion rate through the barrier. A drug with a low water solubility saturates the intrarectal phase at low concentration hindering the subsequent dissolution of the drug particles remaining in the melted excipient. This fact maintains the viscosity of the melted suppository at a ligh level, which slows the migration of the particles. On the other hand, a drug with high water solubility quickly leaves the excipient, producing a high concentration in the intrarectal phase which supports a high diffusion rate across the barrier. The results obtained indicate that drugs with low solubility in water result in low availability, while drugs with good solubility can give an intense and rapid drug supply for a rapid and intense therapeutic response with the dose administered almost completely utilised.

Administration, Rectal↗
PubMed1999

Correlation of in vitro and in vivo paracetamol availability from layered excipient suppositories.

An in vivo investigation of paracetamol availability was carried out on eight healthy volunteers, comparing two paracetamol suppository formulations prepared using two different gliceride bases, a fast drug-releasing one and a slow drug-releasing one, i.e. Witepsol H15 and W35, respectively. The formulations were selected on the basis of a previous in vitro drug release study, which showed that, by superimposing the excipients in two layers within the same suppository, the drug release kinetics could be modulated using different ratios between the two layers. The comparison between the two different formulations in terms of plasma profiles and total amounts of drug excreted in urine revealed an increase in the extent of drug absorption from the layered excipient suppository. As the W35 has a higher monoglyceride content than the H15, this improved paracetamol availability could be ascribed to the absorption-enhancing effect of the monoglycerides. Moreover, the W35 has also a higher viscosity, which could possibly cause the suppository to be retained for a longer time in the lower part of the rectum, where the blood is drained directly to the systemic circulation. It was therefore hypothesized that the enhanced paracetamol availability could be also due to a liver bypass mechanism. For a further examination of the paracetamol absorption kinetics after rectal administration, a one-compartment model was fitted to the drug plasma concentration data. This approach allowed to draw absorption versus time profiles, which showed that a retardation actually occurred in paracetamol absorption when using suppositories containing the slow drug releasing excipient W35. These absorption data were then employed for an A level in vitro-in vivo correlation testing, and a linear relationship was found between in vitro release rate and in vivo absorption rate, both for fast releasing and for the layered excipient suppositories.

Acetaminophen↗
PubMed1999

Liver and kidney kynurenine aminotransferase activity in different strains of rats.

Variations in liver and kidney kynurenine aminotransferase (KAT) activity in Pittsburg-Yoshida, Brown-Norway, albino Wistar, Sprague-Dawley, Long Evans and heterozygous Gunn rats were studied. In liver, values of KAT specific activity, expressed as mumoles of kynurenic acid formed per hour per mg of protein, were different in the groups of Brown-Norway and Pittsburg-Yoshida rats versus Long Evans and Sprague-Dawley rats. The activity expressed as mumoles of kynurenic acid per g of fresh liver showed other differences, being significantly higher in Gunn with respect to other strains of rats and lower in Pittsburg-Yoshida and Brown-Norway rats. In addition, KAT activity was significantly lower in Pittsburg-Yoshida than in Brown-Norway rats. In kidney, the specific activity of kynurenine aminotransferase showed significant differences in the values of Sprague-Dawley and Long Evans rats versus the other strains. The activity expressed per g of fresh tissue was significantly higher in Wistar, Sprague-Dawley, Long Evans and Gunn than in Pittsburg-Yoshida and Brown-Norway rats. No significant differences were found in values between hyperlipidemic Pittsburg-Yoshida and their control Brown-Norway rats. These results high-light the importance of considering various rat strains when inbred animal experimental models are used.

Animals↗
PubMed1999

6-Benzylaminopurine: a plant derived cytokinin inducing positive inotropism by P2-purinoceptors.

Positive inotropic effects induced by 6-benzylaminopurine (6-BAP), kinetin and zeatin were studied in rat atria. The potency order observed was 6-BAP > or = kinetin > zeatin. Suramin, a P2-purinoceptor antagonist, inhibited the positive effect of 6-BAP suggesting the involvement of P2-purinoceptors in the positive effect of this cytokinin. In order to elucidate this point, 6-BAP was used against R-PIA (a P1-purinoceptor agonist) and ATP and UTP (both P2-purinoceptor agonists). 6-BAP did not influence negative inotropism by R-PIA whereas both nucleotides were inhibited after pretreatment with the cytokinin. LY 83583, an inhibitor of cGMP production, reduced the inotropic effect by cytokinin whereas L-NAME, an inhibitor of the L-arginine/nitric oxide pathway, did not influence the effect induced by 6-BAP. Indomethacin, an inhibitor of cyclooxygenase, and neomycin, an inhibitor of phospholipase C, did not significantly modify positive inotropism by 6-BAP. Verapamil, an inhibitor of L-type calcium channels, did not change the positive effect of 6-BAP while TMB-8 and dantrolene, two inhibitors of intracellular calcium release, reduced the increase of contractile tension induced by cytokinin. Our data on rat atria suggest that 6-BAP causes a positive inotropism through activation of P2-purinoceptors, involving modification of cGMP and of intracellular calcium.

Adenine↗
PubMed1999

A comparison of the modulation of antiblastics cytotoxicity by verapamil and dipyridamole in a human colon carcinoma cell line.

This study was designed to compare the activity of two MDR modulators, verapamil and dipyridamole, on the in vitro growth of a human colon carcinoma cell line. The aims were: a) to investigate the different sensitivity of the parental cell line (LoVo S) and the doxorubicin-resistant one (LoVo R) towards the treatment with several antiblastics and their associations with verapamil or dipyridamole; b) to evaluate if the combined use of these drugs with verapamil or dipyridamole increases their cytotoxicity; c) to understand whether the mechanism of action of each modulator is the same. Idarubicin and vinblastine were the most active drugs on both cell lines. LoVo R cells showed cross-resistance to vinblastine, teniposide and mitoxantrone, while chemosensitivity towards cisplatin and cyclophosphamide was almost the same in both cell lines. The inhibitory effect on cell growth was enhanced when the drugs were associated with verapamil, but no difference was detected with cisplatin and cyclophosphamide. Verapamil is thus an effective MDR modulator when used with drugs actively pumped out of tumour cells by P-glycoprotein, while it is ineffective with drugs that induce resistance by different mechanisms. When combined with dipyridamole, a significant result was observed in the case of cisplatin, where a marked increase of cytotoxicity was detected.

ATP Binding Cassette Transporter, Subfamily B, Mem↗