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Biomedical subjects

C Stella

Publications and source records attributed to C Stella.

At least 19 recordsLinked to original sources
PubMed2004

Development of a bioreactor based on trypsin immobilized on monolithic support for the on-line digestion and identification of proteins.

The preparation and characterization of a new trypsin-based bioreactor is here described for on-line protein digestion and peptide analysis. Trypsin was immobilized on an epoxy-modified silica monolithic support with a single reaction step and the amount of immobilized enzyme was found to be 66.07 mg (+/-11.75 S.D.)/column (n = 6). The bioreactor was coupled through a switching valve to an analytical column for the on-line digestion, peptide separation and identification of test proteins by ESI-MS-MS. The influence of various parameters (flow rate, temperature, buffer pH and molarity, etc.) on enzymatic activity was investigated by an experimental design and the mostly significant factor was found to be the flow rate. The efficacy of the reported on-line bioreactor for tryptic mapping is reported for somatostatin and myoglobin, selected as model compounds. Tryptic peptide maps obtained by on-line digestion of myoglobin were compared to those obtained by traditional off-line digestion. Sequence coverage obtained with the on-line protocol (21 peptides, 75.16% coverage of myoglobin sequence) was found to be comparable to the one obtained with the off-line protocol (18 peptides, 76.47% coverage). Sensitivity for myoglobin digestion and identification was 0.1 mg/ml. The reproducibily of the peptide maps in terms of retention time was from 1.53 to 4.31%, R.S.D.

Amino Acid Sequence↗
PubMed2000

Simultaneous stereoselective analysis of venlafaxine and O-desmethylvenlafaxine enantiomers in clinical samples by capillary electrophoresis using charged cyclodextrins.

Capillary electrophoresis (CE) was used for the simultaneous chiral determination of venlafaxine (Vx), a new antidepressant drug and its main active metabolite. O-desmethyl venlafaxine (ODV). Among the charged cyclodextrins (CD) tested, phosphated gamma-CD was the most appropriate. Resolution of Vx and ODV was obtained with 50 mM phosphate buffer (pH 2.5) containing 20 mg/ml of phosphated gamma-CD. After optimisation of the method (including robustness), validation was carried out. Vx and ODV concentrations, as well as the enantiomeric ratio, were investigated in clinical samples. Chiral determination of Vx and ODV was performed after a simple liquid-liquid extraction (LLE). In the tested concentration range (25-500 ng/ml), coefficients of correlation were superior to 0.996. Within-day and between-day accuracy and precision were determined at three different concentrations for each enantiomer. Analyses of clinical samples (n = 16) exhibited non-racemic ratios for Vx and ODV, which suggests a stereoselective metabolism in humans.

Antidepressive Agents, Second-Generation↗
PubMed2000

[Fibrinolytic system after laparoscopic cholecystectomy].

BACKGROUND: Deep-vein thrombosis (DVT) and pulmonary embolism (PE) are the most important causes of morbility and mortality in patients submitted to surgical intervention: some peculiar factors of laparoscopic surgery can modify their risk. The aim of this study is to evaluate possible variations of the fibrinolytic system after cholecystectomy. METHODS: Eighteen patients affected by symptomatic and non-complicated gallstones have been included in this study. They were divided into two groups of nine patients each: the first group was submitted to laparoscopic cholecystectomy (LC) and the second to open cholecystectomy (OC). Antitrombin III (ATIII), fibrinogen degradation products (FDP), tissue plasminogen activator (tPA), and plasminogen activator inhibitor (PAI) have been evaluated preoperatively and 6, 12, 24 and 48 hours after the operation. RESULTS: The levels of ATIII did not present significantly variations. The FDP in both groups were significantly increased 48 hours after open cholecystectomy. Levels of PAI instead were increased in comparison to the basal values at 6, 12, 24, 48 hours with p < 0.05; p < 0.01 and p < 0.05 respectively in patients submitted to OC, in the LC group no variations were observed; a comparison between the groups showed a significant modification (p < 0.05) only at the 12th hour. CONCLUSIONS: The early mobilization of patients in the postoperative course and the lower invasion of LC can oppose the prothrombotic effect in the lower limbs.

Cholecystectomy, Laparoscopic↗
PubMed1996

An in vitro method for evaluating vascular endothelial ADPase activity.

Some xenobiotics, known to promote the development of thrombotic phenomena, affect vascular endothelium ADPase, a regulatory enzyme that inactivates vaso- and platelet-active adenine nucleotides. This proposed new experimental approach represents an improved method of evaluation of vascular endothelial ADPase activity which is assessed by measuring, at pre-established times, the degradation rate of exogenous ADP incubated with aortic bovine patches. The ADP dosage was performed by using a spectrophotometric enzymatic assay. Statistical analyses showed that the method is capable of highlighting the linearity of the ADPase activity time-course, thus indicating that the slopes of time-degradation curves of ADP are a valid index for this endothelial ectoenzyme activity. Results obtained with ADPase inhibiting or stimulating agent confirm that this in vitro method is an efficient tool for estimating the ability of xenobiotics or drugs to modify the nonthrombogenic properties of vascular endothelium.

Adenosine Diphosphate↗
PubMed1993

Delta-aminolevulinic acid transport in Saccharomyces cerevisiae.

1. This work represents the first approach to characterize the transport system of haem pathway precursors, such as delta-aminolevulinic acid (ALA), in two strains of Saccharomyces cerevisiae, a wild type, D27, and a HEM R+ mutant. 2. ALA transport occurs unidirectionally by a sole active system with an apparent KM of 0.10 mM, at the optimum pH of 5.0. ALA uptake is influenced by both the carbon and nitrogen source; this suggests a rather complex regulation mechanism. 3. This transport is not mediated by the general amino acid permease (GAP). 4. ALA uptake is strongly inhibited by compounds harboring a methyl-amine terminus suggesting that this group is essential for ALA transport; however, the electric environment of the carboxylic group may be also important for the interaction between ALA and its transporter active site. 5. We have found differences in ALA transport which would indicate a different regulation mechanism for this system in both strain cells.

Aminolevulinic Acid↗
PubMed1992

Leuprorelin acetate depot vs danazol in the treatment of endometriosis: results of an open multicentre trial.

A national multicentre trial was organized in order to compare the efficacy and safety of leuprorelin acetate depot and danazol in the treatment of endometriosis. Sixty-seven patients with pelvic endometriosis of different severity at laparoscopy were included in the study and followed during the 24 weeks of treatment. Leuprorelin acetate depot 3.75 mg was injected every 24 days, while the daily dose of danazol was 600-800 mg. At the end of the study objective improvements induced by the two drugs were observed by a second laparoscopic examination. In addition, at regular intervals during the study semiquantitative evaluation of subjective symptoms were monitored. Scoring the final objective changes in the two patient groups revealed no significant difference, however the women treated with leuprorelin acetate depot registered significantly better control of pelvic pain. Due to its efficacy, tolerability and ease of use, leuprorelin acetate appears to be an excellent drug for the treatment of endometriosis.

Adult↗
PubMed1988

A statistical study on left ventricular peak filling rate in diabetes.

The importance of non-invasive evaluation of cardiac function in diabetes is well known and radionuclide angiocardiography has become an accepted diagnostic procedure. While the pathophysiological interpretation of systolic parameters is clear, the meaning and determinants of peak filling rate (PFR) remain rather speculative. In the present study, a "pattern recognition" approach, including principal component analysis and hierarchical cluster analysis, has been adopted in order to evaluate the determinants of PFR in a series of 48 non-selected diabetic patients. The results of the study show that: PFR is inversely dependent on age which is its main determinant when systolic function is preserved; PFR is inversely dependent on combined effects of left ventricular dimensions, angina and wall motion; and the duration of diabetes in itself does not influence PFR. These results lead to the following clinically relevant conclusions: (a) It is unlikely that a young diabetic patient without anginal symptoms will have a significant PFR impairment even if the diabetes has been present for a long time. If such impairment is however present, ventricular latent dysfunction is likely to be the cause even if systolic parameters are still normal; (b) A decrease of PFR in a middle-aged diabetic patient without symptoms and with normal systolic function cannot be equated with latent ventricular dysfunction as it may represent only an age-related physiological change without special diagnostic meaning.

Adolescent↗
PubMed1987

Effect of natural beta-interferon on cell proliferation and steroid receptor level in human breast cancer cells.

The effect of natural beta-interferon (beta-IFN) on cell proliferation and steroid receptor level was investigated in CG-5 human breast cancer cell line. beta-interferon determines an appreciable diminution of cell growth, at concentrations ranging from 100 to 1000 IU/ml, which is enhanced when serum content of the culture medium is lowered. Low concentrations of beta-IFN (10-100 IU/ml) produce, after a 5-day treatment, an increase in estrogen receptors (ER) and progesterone receptors (PR). No variation of ER and PR levels is observed when beta-IFN is added directly to the cell homogenate before the assay. Our data suggest that beta-IFN could affect hormone sensitivity through a modification of ER and PR in neoplastic mammary cells.

Breast Neoplasms↗
PubMed1987

[Carcinoembryonic antigen in a review of cases in the literature].

Literature analysis of CEA serum levels tested in 21,147 patients, with non neoplastic and neoplastic disease of various organs, are reported. The sensitivity, the specificity, the positive and negative prognostic trend and the effective value of test in different pathologic situations are evaluated on the basis of organ localization and embryological origin.

Biomarkers, Tumor↗
PubMed1985

Alpha 1-antitrypsin, transferrin, alkaline phosphatase, phosphohexoseisomerase and gamma-glutamyltransferase in breast cyst fluid.

The levels of alpha 1-antitrypsin, transferrin, alkaline phosphatase, phosphohexoseisomerase and gamma-glutamyltransferase were measured in 32 samples of breast cyst fluid, and a wide range of values was obtained. The levels observed in some samples for these parameters, being similar to those of normal serum, might suggest a mechanism of plasma exudation for the formation of breast cyst fluid. Nevertheless, a comparison with the maximum normal serum reference value revealed very high levels of gamma-glutamyltransferase in all of the samples; about 50% also exhibited high levels of phosphohexoseisomerase. These results indicate that the formation of breast cyst fluid takes place with a specific local production, in addition to the mechanism of selective plasma exudation. Moreover, elevated transferrin levels in some cyst fluids are probably the expression of a high biosynthetic activity and could be diagnostically useful in the course of breast gross cystic disease. The importance of these observations from the point of view of diagnostic and prognostic trends are discussed.

Adolescent↗
PubMed1985

[Differential diagnosis of rejection and cyclosporin nephrotoxicity in organ transplantation using exfoliative urinary cytology].

Although the successful results sealing with Cyclosporin therapy in organ transplantation, side effects such as nephrotoxicity due to drug administration, are still partially solved especially concerning differential diagnosis versus rejection in kidney allograft. On this basis the authors evaluated the application of urinary exfoliative cytology for the monitoring of 110 patients who underwent kidney transplant under Cyclosporin regimen. Among them 33 cases showed direct and/or indirect cytopathic signs of nephrotoxicity induced by Cyclosporin, never observed on over 6000 urinary specimens of renal graphed patients treated with conventional therapy. The authors conclude that urinary exfoliative cytology is a useful, safe and easily repeatable method for the differential diagnosis between rejection and Cyclosporin nephrotoxicity at early stage in kidney transplantation.

Cyclosporins↗
PubMed1984

[Clinical renal transplantation: exfoliative urinary cytology in the evaluation of nephrotoxicity induced by cyclosporin therapy].

Cyclosporine significantly improved the results in organ allograft, nevertheless the drug's potential nephrotoxicity is still causative of problems in differential diagnosis between rejection and graft failure due to Cyclosporine in patients who undergo kidney transplantation. The authors evaluate the effectiveness of a simple method as Urinary Exfoliative Cytology (UEC) in a group of 38 patients who received a kidney allograft and post operative treatment with Cyclosporine. The cytological parameters studied were the following: cytology: cellularity, background, urotelial cells, tubular cells, red cells, polinuclear cells, monocytes, histyocytes, lymphocytes, plasmacells, casts (from 0 to 4+). In all the patients was associated the immunological evaluation--lymphocytes subpopulation markers and function--and Cyclosporine serum levels, together with the hematochemical parameters. In 6 patients with a rise of serum creatinine level the UEC evidentiated intracytoplasmatic eosinophile inclusions in the proximal tubular cells, picture never observed in over 5000 UEC examination of patients treated with post-transplant steroids and azathioprine immunosuppressive regimen. Moreover a complete renal function recovery followed the Cyclosporine dose reduction. The authors conclude that the UEC in kidney allograft is a safe, simple and useful method to assess the early renal damage due to Cyclosporine and to make differential diagnosis between nephrotoxicity and rejection.

Cyclosporins↗
PubMed1984

[Cervicovaginal cytology in women wearing intrauterine devices].

Cervical and vaginal smears in 300 women using (a) intrauterine devices (IUD) and in 300 age matched control subjects (b), have been examined. In women using IUD, endometrial cells have been observed also in the second half of menstrual cycle, conversely these cells are present in women belonging to the control group, just in the first half of the cycle. Pattern of cervico-vaginitis due to Chlamydiae, Actinomyces and Eubacteria have been observed in higher percentage in women IUD wearers 58% of (a) group and 19.3% of (b) group (P less than 0.005). These patterns have often been characterized by the presence of repair cells. Implications in the evaluation of vaginal smears are discussed.

Actinomycosis↗
PubMed1984

[Cytology of breast cysts].

280 cytologic samples obtained by centrifugation of breast cyst fluids were studied. The results of the study on the cellular component and of the background are reported. The analysis was carried out on the cytomorphological aspects of the background, non epithelial cells, normal epithelial cells (foam, galactophoric, apocrine, papillary pictures) and malignant cells. Having described the single cytotypes, their diagnostic values in relation to other techniques are discussed.

Adolescent↗