Biomedical subjects

J Prieto

Publications and source records attributed to J Prieto.

At least 127 records · Page 7Linked to original sources

PubMed1999

Interferon alfa subtypes and levels of type I interferons in the liver and peripheral mononuclear cells in patients with chronic hepatitis C and controls.

Viral infections stimulate the transcription of interferon type I, which includes IFN-alfa (IFN-alpha) (13 subtypes) and IFN-beta (a single substance). Hepatitis C virus (HCV) infection is remarkable by its ability to evade host antiviral defenses; however, there is little information as to whether endogenous IFN is activated or not in this disease. Additionally, despite the fact that the various IFN-alpha subtypes may differ in biological activity, there are no data concerning the IFN-alpha subtypes specifically expressed in normal and diseased liver tissue. Thus, we have analyzed the IFN-alpha subtypes and the mRNA levels of type I IFNs in samples of normal liver tissue and in liver from patients with chronic hepatitis C. Similar studies were performed in peripheral blood mononuclear cells (PBMC) from patients and controls. After amplification and cloning of IFN-alpha cDNA, we observed that 98 of the 100 clones from normal liver tissue corresponded to the IFN-alpha5 subtype. However, in livers with chronic hepatitis C and in PBMC from controls and patients, a variety of subtypes, in addition to IFN-alpha5, were detected, suggesting a participation of infiltrating leukocytes in the production of IFN-alpha in livers with chronic hepatitis C. As compared with controls, patients with chronic hepatitis C showed a significant increase in IFN-beta mRNA in both the liver and PBMC, while IFN-alpha mRNA was significantly increased in PBMC but markedly reduced in liver tissue. In conclusion, IFN-alpha5 is the sole IFN-alpha subtype expressed in normal liver tissue. The hepatic levels of IFN-alpha are reduced in chronic hepatitis C, an event that may favor viral persistence.

Adult↗

PubMed1999

Conversion of liver transplant recipients on cyclosporine with renal impairment to mycophenolate mofetil.

The management of liver transplant recipients with renal function impairment remains controversial because cyclosporine withdrawal from triple immunosuppression regimens may be followed by graft rejection. A nonnephrotoxic and powerful immunosuppressant such as mycophenolate mofetil (MMF) could allow a reduction of cyclosporine dosage or its withdrawal and an improvement in renal function in these patients. Eleven patients with serum creatinine levels greater than 1.5 mg/dL, normal graft function, and a rejection-free period of at least 1 year started MMF at a dose of 2000 mg/d (reduced in case of adverse events) while cyclosporine dosage was slowly reduced. At last follow-up (63 +/- 5 weeks), 7 patients remained free of cyclosporine (6 of those patients are also free of steroids), 2 patients reduced their cyclosporine dose, and 2 patients developed mild acute rejection that responded to a switch to tacrolimus therapy. Serum creatinine and urea levels in the 7 patients free of cyclosporine decreased from 2.22 +/- 0.13 to 1.90 +/- 0.19 mg/dL (P =.05) and 0.95 +/- 0.10 to 0.60 +/- 0.10 g/L (P <.001), respectively. Creatinine clearance increased from 38.16 +/- 5.60 to 47.01 +/- 6. 76 mL/min (P =.005). Control of arterial hypertension also improved. Tolerance to MMF was good, but 6 patients required dose reductions, mainly because of asymptomatic anemia. In conclusion, in liver transplant recipients with stable graft function, MMF may allow cyclosporine dose reduction or discontinuation, thus improving renal function and the control of arterial hypertension. This change of treatment must be carefully monitored because of the frequent need for MMF dose reduction and the risk for rejection.

Aged↗

PubMed1999

Assessment of biliary bicarbonate secretion in humans by positron emission tomography.

BACKGROUND & AIMS: Positron emission tomography (PET) allows imaging and quantitative analysis of organ functions in basal and stimulated conditions. We have applied this method to the study of biliary bicarbonate secretion in humans. METHODS: PET was performed in 5 healthy subjects and 13 patients with hepatobiliary disorders after intravenous injection of NaH11CO3. In each case the study was performed in basal conditions and after secretin stimulation. Positron emission from the hepatic area was scanned, and normalized uptake values for parenchymal and hilar regions were estimated. RESULTS: In healthy individuals, the injection of NaH11CO3 resulted in a peak uptake of the label in parenchymal and hilar regions 2-3 minutes after the injection. In both normal and cirrhotic subjects, secretin administration increased bicarbonate uptake in the parenchymal region, followed by accumulation of the label in the perihilar area. Normal basal uptake with absent response to secretin was registered in extrahepatic biliary obstruction and in untreated primary biliary cirrhosis (PBC). The secretin response was present in patients with PBC undergoing treatment with ursodeoxycholic acid. CONCLUSIONS: PET allows investigation of biliary bicarbonate secretion in humans. An impaired response to secretin was observed in cholestatic conditions. Preliminary data suggest that ursodeoxycholic acid might improve the response to secretin in PBC.

Adult↗

PubMed1999

Ex-vivo expansion and maturation of CD34-positive hematopoietic progenitors optimization of culture conditions.

The aim of this study was to look for an ex vivo culture system for clinical application. We evaluated the ex vivo expansion of peripheral blood CD34+ cells in gas-permeable bags and whether or not an exogenous protein source would be required in these kind of cultures. We also evaluated maturation of the cells during culture. Cells were cultured for 15 days in medium supplemented with SCF, G-CSF, IL3 and IL6. The bags supported the expansion of hematopoietic cells in a similar manner to small scale flasks system: (a) the expansion means of total nucleated cells on day +5 were 12.5-fold for bag versus 5-fold for flask, on day +10 were 44.12-fold for bag versus 41-fold for flask and on day +15 were 67.7-fold for bag versus 84.2-fold for flask, (b) the peak values of CFU-GM were reached on day +10 (9.2-fold for bag vs. 12-fold for flask), and (c) maximal expansion of CD15+/CD11b- population occurred on day +10 (517.5-fold for bag vs. 2959.2-fold for flask). So, we did not find any advantages by culturing further than day +10. We subsequently investigated the use of serum-free medium. The study showed better results when we used medium supplemented with autologous plasma versus serum-free system. In summary, these data described a strategy of culture clinically feasible and safe, using gas-permeable bags, and the kinetics and differentiation of neutrophils and neutrophil precursors from selected CD34+ cells in liquid cultures. Ex vivo expansion of this population might result in earlier engraftment as compared with that for selected stem cells alone.

Adult↗

PubMed1999

Antioxidant status and glutathione metabolism in peripheral blood mononuclear cells from patients with chronic hepatitis C.

BACKGROUND/AIMS: Oxidative stress could play a role in the pathogenesis of hepatitis C virus infection. We investigated the oxidant/antioxidant status in peripheral blood mononuclear cells from patients with chronic hepatitis C and controls. METHODS/RESULTS: Lipid peroxidation products and superoxide dismutase activity in peripheral blood mononuclear cells were higher in chronic hepatitis C patients than in healthy subjects while glutathione S-transferase activity was reduced in patients as compared to controls. Catalase, glutathione peroxidase and glutathione reductase were similar in chronic hepatitis C and normal individuals. No statistically significant differences were found between patients and controls with regard to glutathione levels in peripheral blood mononuclear cells, but 35% of patients with chronic hepatitis C showed values of glutathione and oxidized glutathione which were below and above, respectively, the limits of normal controls. Finally, the glutathione synthetic capacity of the cytosol of peripheral blood mononuclear cells was significantly higher in patients than in controls, indicating increased glutathione turnover in lymphocytes from patients with chronic hepatitis C. CONCLUSIONS: Oxidative stress is observed in peripheral blood mononuclear cells from chronic hepatitis C patients. This process might alter lymphocyte function and facilitate the chronicity of the infection.

Adult↗

PubMed1999

Early predictors of response to treatment in patients with chronic hepatitis C.

The term sustained response should be applied to patients with negative serum HCV-RNA and normal values of serum transaminases 6 months after interferon withdrawal. To investigate which factors identify sustained responders early during treatment we analysed 18 reports which used the definition sustained response. Eight reports, comprising 988 patients, have studied the value of early clearance of viraemia as a predictor of sustained response using multivariate analysis and all of them found that this was the strongest predictor of a sustained response. Determination of HCV-RNA 4 or 12 weeks after initiation of IFN therapy predicts treatment outcome more accurately than baseline viral load (the best pre-treatment predictor). ALT levels during the first 12 weeks of treatment have lower predictive value than early viral clearance. The sensitivity of a negative HCV-RNA test is similar at week 4 and at week 12 of therapy while the specificity and the accuracy is higher at week 4. The value of persistent viraemia for early prediction of no response is higher than 97%, with similar values at weeks 4 and 12. Persistence of HCV-RNA in serum at week 4 strongly indicates that the patient will not respond to treatment and in these cases interruption of treatment or other therapeutic options could be considered.

Antiviral Agents↗

PubMed1999

Efficacy of trovafloxacin in an in vitro pharmacodynamic simulation of an intraabdominal infection.

An in vitro model simulating trovafloxacin concentrations in human serum after standard doses was used to investigate the activity of this drug with time against Bacteroides fragilis, Escherichia coli, Enterococcus faecalis and Staphylococcus aureus. Antibiotic concentrations used for each incubation period were: 4.24 mg/l (0-1 h), 3.69 mg/l (1-3 h), 3.25 mg/l (3-6 h), 2.38 mg/l (6-8 h), 1.35 mg/l (8-24 h). A 99.9% initial inoculum reduction (> 3 log10 cfu/ml) was defined as bactericidal activity. Bactericidal activity against these organisms was obtained with trovafloxacin after the first hour of incubation, and similar activity was obtained against B. fragilis, E. faecalis and S. aureus after 3 h, when they were tested individually. When the strains were tested as mixed culture, there was bactericidal activity against E. coli after 1 h incubation and after 3 h for S. aureus. This activity was observed against B. fragilis and E. faecalis after 6 h incubation in the mixed culture assays and after 3 h when organisms were tested individually. Regrowth was not observed over a 24 h period. These data show that trovafloxacin might be effective in intraabdominal infections caused by mixed aerobic and anaerobic microorganisms.

Abdominal Abscess↗

PubMed1999

Intratumoral injection of bone-marrow derived dendritic cells engineered to produce interleukin-12 induces complete regression of established murine transplantable colon adenocarcinomas.

Stimulation of the antitumor immune response by dendritic cells (DC) is critically dependent on their tightly regulated ability to produce interleukin-12 (IL-12). To enhance this effect artificially, bone marrow (BM)-derived DC were genetically engineered to produce high levels of functional IL-12 by ex vivo infection with a recombinant defective adenovirus (AdCMVIL-12). DC-expressing IL-12 injected into the malignant tissue eradicated 50-100% well established malignant nodules derived from the injection of two murine colon adenocarcinoma cell lines. Successful therapy was dependent on IL-12 transfection and was mediated only by syngeneic, but not allogeneic BM-derived DC, indicating that compatible antigen-presenting molecules were required. The antitumor effect was inhibited by in vivo depletion of CD8+ T cells and completely abrogated by simultaneous depletion with anti-CD4 and anti-CD8 mAbs. Mice which had undergone tumor regression remained immune to a rechallenge with tumor cells, showing the achievement of long-lasting systemic immunity that also was able to reject simultaneously induced concomitant untreated tumors. Tumor regression was associated with a detectable CTL response directed against tumor-specific antigens probably captured by DC artificially released inside tumor nodules. Our results open the possibility of similarly treating the corresponding human malignancies.

Adenocarcinoma↗

PubMed1999

Airway inflammation and altered alveolar macrophage phenotype pattern after repeated low-dose allergen exposure of atopic asthmatic subjects.

BACKGROUND: The alveolar macrophage (AM) constitutes an important link between pulmonary innate and adaptive immunity due to its antigen-presenting capacity and ability to express different immunomodulating mediators. The role of AMs in the pathogenesis of allergic inflammation has yet to be fully determined. OBJECTIVE: To investigate clinical effects and any change in the AM phenotype pattern after inhalation of sub-clinical doses of allergen by asthmatic patients. METHODS: Eight subjects with allergic asthma underwent repeated low-dose allergen provocations equivalent to 10% of PD20. AMs recovered with bronchoalveolar lavage (BAL) were characterized by flow cytometric analysis of adhesion molecules, co-stimulatory molecules and markers for AM population activation and heterogeneity. RESULTS: An allergic airway inflammation, sub-clinical in six out of eight subjects, was obtained after low-dose allergen provocations, as determined by increased airway methacholine reactivity, increased BAL fluid total cell and eosinophil counts and increased serum ECP levels. The AMs showed a post-challenge altered phenotype pattern with a decreased expression of CD11a, CD16, CD71 and HLA class I and an increased expression of CD11b and CD14. The AMs were positive for CD83 and a weak post-challenge increase in the CD83 expression was found. CONCLUSION: Repeated low-dose allergen exposure induces an allergic airway inflammation in asthmatic subjects. The inflammation is associated with an altered AM phenotype pattern, consistent with an influx of monocytes and a hypothetical increased accessory cell function in the airways, possibly contributing to the development and sustenance of airway inflammation in asthma.

Adult↗

PubMed1999

Gene therapy of viral hepatitis and hepatocellular carcinoma.

Gene therapy represents an attractive approach to treat a great variety of diseases, both inherited and acquired, and it is moving slowly from a proof-of-principle phase to a wide application in most medical fields. Liver cancer and viral hepatitis are natural targets for this new therapeutic alternative due to the lack of success of conventional antitumoral and antiviral treatments and the ominous prognosis related with liver tumours. Gene therapy for viral hepatitis is aimed to boost the patient immune response against viral antigens or to make cells resistant to infection by blocking the viral life cycle. Gene transfer techniques applied to the treatment of hepatocellular carcinoma include drug sensitization by suicide genes, genetic immunotherapy, normal tissue protection by transfer of the multidrug resistance gene, replacement of tumour suppressor genes, inhibition of oncogenes and modifications of the biology of the tumour (antiangiogenesis). However, major advances in our understanding of the regulation of gene expression, design of the expression cassettes and development of more efficient gene transfer vectors are mandatory before gene therapy can become a widely used therapeutic modality.

Carcinoma, Hepatocellular↗

PubMed1999

Upper extremity infections in patients with diabetes mellitus.

Forty-five consecutive diabetic patients with 46 upper extremity infections who underwent surgical debridement were retrospectively reviewed. The infections involved the skin or subcutaneous tissue in 19 patients and the fascia, tendon, muscle, or bone in 27. Twenty-three infections (50%) required a single operation and 23 required more than 1. Eighteen infections (39%) required an amputation and there were 3 deaths directly related to an infection. Six of 7 infections in which anaerobic organisms were cultured culminated in amputation. Four patients were diagnosed with necrotizing fasciitis. Twenty-one cultures (46%) were polymicrobial. An increased rate of amputation was associated with deep infections below the subcutaneous tissue, renal failure, and infections with gram-negative, anaerobic, or polymicrobial cultures. An increased rate of repeat surgery and a prolonged hospitalization were associated with deep infection and polymicrobial infections.

Amputation, Surgical↗

PubMed1999

Activity of voriconazole: post-antifungal effect, effects of low concentrations and of pretreatment on the susceptibility of Candida albicans to leucocytes.

This study examined: (i) the post-antifungal effect (PAFE) of Voriconazole (UK 109,496) on Candida albicans, at 2 concentrations (MIC and 4 x MIC) in the presence or absence of 10% human serum; (ii) the activity of low concentrations of the drug (1/4 x MIC) on yeasts that had previously been exposed to Voriconazole (PAFSE) with or without 10% human serum; and (iii) the effect of Voriconazole pretreatment on the fungicidal activity of leucocytes and serum against C. albicans (PALE). Two concentrations (0.25 and 1 mg/l) of Voriconazole induced no PAFE against C. albicans between -4.3 and -1.4 h, but when the assays were performed in the presence of serum, positive and concentration-dependent PAFEs were obtained (0.2-4.1 h). Pretreated yeasts were more susceptible than untreated yeasts to low concentrations (0.0625 mg/l) of Voriconazole, so the drug showed positive PAFSE that was dependent on the concentration used in pretreatment without serum (0.3-1.9 h) or with 10% human serum (0.5-2.5 h). Pretreatment of the growing C. albicans cells with Voriconazole (0.25 mg/l) increased their vulnerability to killing by leucocytes during the last 2 h (p < 0.05), leading to PALE of 2 h. The results suggest that these effects might be used to evaluate the in vivo activity of an antifungal agent. The sum of the durations of these effects (PAFE, PAFSES and PALE) cause a considerable delay in yeast growth in treated cultures compared with control cultures.

Antifungal Agents↗

PubMed1999

T(h)1 but not T(h)0 cell help is efficient to induce cytotoxic T lymphocytes by immunization with short synthetic peptides.

Immunization of BALB/c mice with peptide HVSGHRMAWDMMMNWA, encompassing residues 121-135 from hepatitis C virus E1 protein, induced CD4(+) T(h)1 cells as well as a long-lasting CD8(+) cytotoxic T lymphocyte (CTL) response in vivo when the peptide was administered s.c. with or without incomplete Freund's adjuvant. Using truncated peptides from this sequence it was shown that the determinant recognized by cytotoxic T cells was encompassed by residues SGHRMAWDM. Deletion of residues from the N-terminus or the C-terminus of the wild-type peptide abrogated its helper character. When Val122 of the wild peptide was replaced by Ala, the ability to induce a cytotoxic response was lost concomitantly with the loss of the T(h)1 pattern of cytokine production. Interestingly, the Ala-modified peptide, when co-immunized with a peptide encompassing residues 323-329 from ovalbumin (OVA), which is able to induce a T(h)1 response in BALB/c mice, restored the capacity of the modified peptide to induce CTL. However, co-immunization of the Ala-modified peptide with a peptide encompassing residues 106-118 from sperm whale myoglobin, which induces a T(h)0 cytokine profile in BALB/c mice, was much less efficient than the OVA peptide to restore CTL induction. These results demonstrate that CTL induction with a short synthetic peptide requires that this peptide contains domains recognized by T(c) cells as well as by T(h)1 cells. For those peptides that do not contain this type of T(h) domain, competent T cell help can be provided by co-immunization with a distinct peptide that is able to stimulate a T(h)1 response.

Amino Acid Sequence↗

PubMed1999

Immunogenicity of variable regions of hepatitis C virus proteins: selection and modification of peptide epitopes to assess hepatitis C virus genotypes by ELISA.

The immunogenicity of variable regions of hepatitis C virus (HCV) proteins was studied by ELISA by using 543 synthetic peptides from 120 variable regions and 90 sera from HCV-infected patients. Some regions from certain genotypes were less immunogenic, or even non-immunogenic, compared with their equivalents in other genotypes. However, the mean recognition of all peptides from genotypes 1a, 1b and 3 by sera infected with genotypes 1a, 1b and 3, respectively, showed no significant differences, suggesting a similar overall immunogenicity of variable regions from these genotypes. Proteins NS4a, NS4b and NS5a were found to be the most immunogenic. Recognition of individual peptides by the sera of infected patients showed that the humoral response against HCV is patient-dependent. The work shows that 15-mer peptides may encompass several B-cell epitopes. These epitopes may lie in slightly different positions in different genotypes. Thirty-one percent of the 543 peptides were recognized by some of the 35 healthy donors. This may be a reflection of the large number of antigens to which they had been exposed, but it may also reflect a strategy of HCV to respond to immune pressure. After selection and modification, a set of 40 peptides was used to assess genotypes 1a, 1b, 1, 2 and 3 in the sera of HCV-infected patients, with sensitivities of 34.1, 48.5, 68.8, 58.3 and 48.9% and specificities of 100, 99.1, 97.1, 99.5 and 99%, respectively. The overall sensitivity and specificity for the assessment of genotypes 1, 2 and 3 were 64 and 98%, respectively.

Amino Acid Sequence↗

PubMed1999

Unmasking of the trigemino-accessory reflex in accessory facial anastomosis.

OBJECTIVE: To evaluate the possible blink reflex responses in facial muscles reinnervated by the accessory nerve. METHOD: Eleven patients with a complete facial palsy were submitted to a surgical repair by an accessory facial nerve anastomosis (AFA). In this pathological group, blink reflex was studied by means of percutaneous electrical stimulation of the supraorbital nerve and recording from the orbicularis oculi muscle. A control group comprised seven normal people and seven patients with a complete Bell's facial palsy; in this group, responses on the sternocleidomastoideus (SCM) muscles were studied after supraorbital nerve stimulation. RESULTS: All the patients with AFA showed a consistent degree of facial reinnervation. Ten out of the 11 patients with AFA showed reflex responses; in six, responses were configured by a double component pattern, resembling the R1 and R2 components of the blink reflex; three patients had an R1-like response and one patient showed a unique R2 component. Mean values of latencies were 15.2 (SD 4.6) ms for the R1 and 85.3 (SD 9.6) ms for the R2. In the control group, eight out of 14 people had evidence of reflex responses in the SCM muscles; these were almost exclusively configured by a bilateral late component (mean latency 63.5 (SD15.9) ms) and only one of the subjects showed an early response at 11 ms. CONCLUSION: The trigemino-accessory reflex response in the pathological group was more complex and of a significantly higher incidence than in the control group. These differences could be tentatively explained by a mechanism of synaptic plasticity induced by the impairment of the efferent portion of the reflex. This could unmask the central linking between the trigeminal and the accessory limbs of the reflex. The findings described could be a demonstration of neurobionomic function in the repairing process of the nervous system.

Accessory Nerve↗

PubMed1999

Effect of insulin-like growth factor I on in vivo intestinal absorption of D-galactose in cirrhotic rats.

Insulin-like growth factor I (IGF-I) bioavailability is reduced in liver cirrhosis, a condition frequently associated with malnutrition. We have analyzed in vivo absorption of D-galactose by jejunal loops in rats with CCl4-induced liver cirrhosis and the influence of IGF-I on intestinal sugar transport in this disease. Two different study protocols were followed. In protocol 1, healthy control rats or cirrhotic rats received saline or IGF-I (2 micrograms . 100 g body wt-1. day-1) for 2 wk. In protocol 2, control and cirrhotic rats received saline or IGF-I as a bolus injection of 1 microgram/100 g body wt followed by continuous infusion of the same dose for 100 min. In vivo D-galactose absorption was reduced in cirrhotic rats compared with healthy controls. IGF-I, as both a chronic (protocol 1) and acute treatment (protocol 2), was able to improve sugar transport in cirrhotic rats but had no effect on sugar absorption in healthy rats. A significant elongation of enterocyte microvilli was observed in cirrhotic animals; this alteration was totally or partially corrected by chronic or acute IGF-I administration. Our results show that in vivo jejunal sugar transport and microvilli structure are altered in liver cirrhosis and that IGF-I, among other effects, may correct these changes by modulating cytoskeletal organization in enterocytes.

Animals↗

PubMed1999

Does the degree of penicillin susceptibility of Streptococcus pneumoniae affect the bactericidal activity of co-amoxiclav versus oral cephalosporins at physiological concentrations? An in vitro pharmacodynamic simulation.

An in vitro model simulating amoxicillin-clavulanic acid (co-amoxiclav) versus oral cephalosporin serum concentrations was used to explore activity over time against penicillin-susceptible and non-susceptible Streptococcus pneumoniae. Initial inoculum reduction > 4 log cfu/ml (>99.9%) was obtained with co-amoxiclav against both strains. Cefuroxime, cefpodoxime and cefaclor achieved a similar reduction against the susceptible strain, but no reduction against the non-susceptible strain.

Amoxicillin-Potassium Clavulanate Combination↗

PubMed1999

In vitro bactericidal activity of peak serum concentrations of co-amoxiclav, amoxicillin and vancomycin against methicillin-resistant Staphylococcus aureus.

In order to explore the bactericidal activity of concentrations similar to the peak serum concentrations obtained after a single i.v. dose of 2,000/200 mg co-amoxiclav and 500 mg vancomycin, killing curves with co-amoxiclav (69/10 microg/ml), amoxicillin (69 microg/ml), clavulanic acid (10 microg/ml), and vancomycin (15 microg/ml) were performed against two isogenic (ss-lactamase positive and negative) methicillin-resistant Staphylococcus aureus strains in cation-supplemented Mueller-Hinton broth with 2% NaCl incubated at 35 degrees C. Colony counts were performed at 0, 1, 2, 3 and 4 hours in Mueller- Hinton plates supplemented with 4% NaCl and 25 microg/ml oxacillin to measure the resistant population. Similar initial inocula reductions were obtained for amoxicillin-clavulanic acid and vancomycin for both strains, and significant differences were found in comparison to the control. Clavulanic acid decreased the growth rate of the ss-lactamase negative strain when compared to control curves. The penicillin-binding protein 2a affinity of old ss-lactams in conjunction with clavulanic acid overcoming ss-lactamase resistance may explain these results.

Amoxicillin↗