Biomedical subjects

V Ricci

Publications and source records attributed to V Ricci.

At least 55 records · Page 3Linked to original sources

PubMed1996

Contributions of individual mechanisms to fluoroquinolone resistance in 36 Escherichia coli strains isolated from humans and animals.

Twenty-eight human isolates of Escherichia coli from Argentina and Spain and eight veterinary isolates received from the Ministry of Agriculture Fisheries and Foods in the United Kingdom required 2 to > 128 micrograms of ciprofloxacin per ml for inhibition. Fragments of gyrA and parC encompassing the quinolone resistance-determining region were amplified by PCR, and the DNA sequences of the fragments were determined. All isolates contained a mutation in gyrA of a serine at position 83 (Ser83) to an Leu, and 26 isolates also contained a mutation of Asp87 to one of four amino acids: Asn (n = 14), Tyr (n = 6), Gly (n = 5), or His (n = 1). Twenty-four isolates contained a single mutation in parC, either a Ser80 to Ile (n = 17) or Arg (n = 2) or a Glu84 to Lys (n = 3). The role of a mutation in gyrB was investigated by introducing wild-type gyrB (pBP548) into all isolates; for three transformants MICs of ciprofloxacin were reduced; however, sequencing of PCR-derived fragments containing the gyrB quinolone resistance-determining region revealed no changes. The analogous region of parE was analyzed in 34 of 36 isolates by single-strand conformational polymorphism analysis and sequencing; however, no amino acid substitutions were discovered. The outer membrane protein and lipopolysaccharide profiles of all isolates were compared with those of reference strains, and the concentration of ciprofloxacin accumulated (with or without 100 microM carbony cyanide m-chlorophenylhydrazone [CCCP] was determined. Twenty-two isolates accumulated significantly lower concentrations of ciprofloxacin than the wild-type E. coli isolate; nine isolates accumulated less then half the concentration. The addition of CCCP increased the concentration of ciprofloxacin accumulated, and in all but one isolate the percent increase was greater than that in the control strains. The data indicate that high-level fluoroquinolone resistance in E. coli involves the acquisition of mutations at multiple loci.

Animals↗

PubMed1996

Effect of Helicobacter pylori on gastric epithelial cell migration and proliferation in vitro: role of VacA and CagA.

Helicobacter pylori infection is associated with inflammation of the gastric mucosa and with gastric mucosal damage. In this study, we sought to test the hypothesis that two H. pylori virulence factors (VacA and CagA) impair gastric epithelial cell migration and proliferation, the main processes involved in gastric mucosal healing in vivo. Human gastric epithelial cells (MKN 28) were incubated with undialyzed or dialyzed broth culture filtrates from wild-type H. pylori strains or isogenic mutants defective in production of VacA, CagA, or both products. We found that (i) VacA specifically inhibited cell proliferation without affecting cell migration, (ii) CagA exerted no effect on either cell migration or proliferation, and (iii) undialyzed H. pylori broth culture filtrates inhibited both cell migration and proliferation through a VacA- and CagA-independent mechanism. These findings demonstrate that, in addition to damaging the gastric mucosa, H. pylori products may also impair physiological processes required for mucosal repair.

Antigens, Bacterial↗

PubMed1996

Significance of ammonia in the genesis of gastric epithelial lesions induced by Helicobacter pylori: an in vitro study with different bacterial strains and urea concentrations.

Two Helicobacter pylori products cause cell damage both in vivo and in vitro: ammonia, from bacterial urease activity, and a vacuolating toxin named VacA. In this in vitro study, the vacuolating effect of H. pylori broth culture filtrate from a VacA-positive/urease-positive strain is compared with that of a VacA-negative/urease-positive strain and a VacA-negative/urease-negative strain. The effect of VacA and ammonia was evaluated with and without addition of 10 mM urea, a physiological concentration for the human stomach, and with and without addition of 0.5 mg/ml acetohydroxamic and (AHA), an urease inhibitor. Our data show that: (1) both urease-positive H. pylori strains caused cell vacuolation in the absence of urea, the VacA-positive strain being approximatively twice as potent as the VacA-negative strain; (2) addition of urea to the culture medium caused an approximatively 3-fold increase in the vacuolating activity of both urease-positive strains; (3) a VacA-negative/urease-negative strain did not exert any vacuolating effect, either in the presence or in the absence of urea; (4) the ratio between cell vacuolation induced by VacA-positive and VacA-negative strains was enhanced by the presence of AHA: ratio was about 2 in the absence of AHA and about 6 in the presence of AHA, either with or without urea added. The increment of vacuolation is likely due to an interaction between AHA and VacA. In conclusion, a VacA-negative/urease-positive strain becomes highly cytotoxic when physiological levels of urea are present in the incubation medium. This finding suggests that all urease-positive H. pylori strains, both with and without VacA expression, should be considered as potentially cytotoxic for the human gastric mucosa, although VacA enhances the severity of cell damage.

Ammonia↗

PubMed1995

Intestinal alkaline phosphatase can transphosphorylate thiamin to thiamin monophosphate during intestinal transport in the rat.

Intestinal alkaline phosphatase (IAP) purified from calf intestine and IAP present in the brush border membrane of rat small intestine effectively transphosphorylated thiamin (T) to thiamin monophosphate (TMP) using Na2-beta-glycerophosphate or Na2-creatine phosphate as phosphate donors at pH 8.5. TMP production in the brush border membrane was very small and corresponded to 0.001-0.01 percent of the total inorganic phosphate simultaneously released by the enzyme activity. This reaction, however, could account for TMP formation independently from that much more important due to the hydrolysis of thiamin pyrophosphate during T intestinal absorption.

Alkaline Phosphatase↗

PubMed1995

[Operative stress and neuroendocrine changes: influence of anxiety, pain, and drugs].

In this study we took into consideration the neuroendocrine alterations caused by surgical stress, studying the cortisol and prolactin's course in plasma, during the period between preanesthesia and the morning after operation. Our research was particularly interested in identifying the influence of anxiety, pain and drugs. At this purpose, twenty-four patients (ASA 1-2) submitted to abdominal surgery, were subdivided in to two groups of twelve members each. In the first (group G) a general inhalising anesthesia with analgesic component was performed; in the second (group B) a selective peridural anesthesia associated with slight general anesthesia, the so-called blended anesthesia. The interpretation of the results showed an action particularly on prolactin, and of pain on cortisol. Thus, a proper use of anesthetic drugs, even if some of them have sure stimulating properties, is useful to reduce the hormonal response. Therefore as good is the control of anxiety and pain, so good is the hormonal metabolic reaction to surgical stress. If the measures to reduce anxiety are limited to a suitable preanesthesia (possibly combined with psychological preparation), on pain, on the contrary, it is possible to act with suitable technology, first of all by locoregional anesthesia. It is, however, important to underline that the best therapy of pain is its prevention.

Adult↗

PubMed1995

[Continuous spinal analgesia in home care of oncologic pain].

The authors in this study, after a short survey of the most important therapeutic techniques for cancer pain, report their results in the treatment of 18 patients suffering from incurable disease. It was impossible to dismiss them from hospital care on account of a painful symptomatology not controllable by oral morphine or owing to excessive collateral morphinic consequences. The analgetic technique employed was continuous intrathecal infusion of morphine, clonidine, droperidol and, in 10 cases, bupivacaine. Drug delivery systems, totally internalized, except infusion pump, were always utilized. Adequate pain relief was obtained, within - 5 days, in all the patients. Family membres, in the same period, learnt the infusion circuit action. At this point the patients were dismissed and treated with home care. The average time of assistance was 140 days, and very moderate variations in posology were necessary. Hospital reentrance, really little numerous, happened only when no member of palliative care service was present. Reasons were no bodily pain, but the total suffering of cancer disease. No complication nor collateral consequences were never found.

Analgesics, Opioid↗

PubMed1993

Na+,K(+)-ATPase of gastric cells. A target of Helicobacter pylori cytotoxic activity.

The present study shows a direct impairing action of a cytotoxin-producing Helicobacter pylori strain on the Na+,K(+)-ATPase (evaluated as K(+)-dependent phosphatase activity) of human gastric epithelial cells in culture. The toxin itself is likely involved in this action which may also account for the cell edema found in vivo in Helicobacter pylori-colonized stomach.

Adenocarcinoma↗

PubMed1988

Intestinal transport of thiamin and thiamin monophosphate in rat everted jejunal sacs: a comparative study using some potential inhibitors.

Rat everted jejunal sacs were incubated for 15 and 30 min at 37 degrees C in oxygenated Krebs-Henseleit buffer, pH 7.4, containing 0.2 microM [3H]-thiamin (3H-T) or [3H]-thiamin monophosphate (3H-TMP) with and without 10 mM 1-phenylalanine (PAL) or 2.5 mM levamisole (LEV). The concentrations of 3H-T and its phosphoesters in sac wall and serosal fluid were determined by a radiometric method after electrophoretic separation. In separate experiments, thiamin pyrophosphokinase (TPKase) and thiamin pyrophosphatase (TPPase) activities were determined in mucosal scrapings, with and without PAL or LEV, by using a radiometric and a colorimetric method, respectively. 3H-TMP was transported partly unchanged by an active mechanism similarly to 3H-T, but less efficiently. During transport, 3H-TMP was also enzymatically transformed to thiamin (T) and thiamin pyrophosphate, which accumulated in the tissue. In the serosal fluid, the concentration of 3H-TMP exceeded that of 3H-T. Presence of PAL or LEV with 3H-T or 3H-TMP in the incubation medium reduced the serosal transport and the tissue content of T compounds. LEV caused a dose-dependent inhibition of TPKase without affecting TPPase, whereas PAL inhibited both activities to about the same extent. These results indicate that the transport of TMP involves a number of different processes similar to those responsible for T transport. The effects of PAL and LEV underline the importance of phosphorylation-dephosphorylation coupling.

Animals↗

PubMed1981