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Biomedical subjects

L Maestri

Publications and source records attributed to L Maestri.

65 records · Page 4Linked to original sources
PubMedDate not supplied

Medroxyprogesterone-acetate reverses the MDR phenotype of the CG5-doxorubicin resistant human breast cancer cell line.

In malignant cells multidrug resistance (MDR) is frequently associated with the expression of a 170 KDa P-glycoprotein (P-gp) in the plasma membrane. P-gp acts as an ATP-dependent efflux pump causing a decreased intracellular accumulation of structurally unrelated natural anticancer agents such as anthracyclines. Doxorubicin (DX) resistance is mostly related to the multidrug resistance gene product P-gp. In our experiments the revertant activity of medroxyprogesterone acetate (MPA) in comparison to that of the well known revertant agent verapamil (VRP) was investigated. In vitro tests were carried out on a DX-resistant variant (CG5/DX) obtained in our laboratory from the parental CG5 human breast cancer cell line by continuous exposure to the drug. The ability of MPA to modulate intracellular DX accumulation and to reverse MDR was evaluated. MPA appeared more active than VRP in reversing MDR, suggesting a possible role of this synthetic progestin as chemosensitizing agent in the clinical management of anthracycline-resistant breast cancer.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

[Determination of low levels of urinary trans,trans-muconic acid].

A method is described which allows determination of urinary t,t-muconic acid (MA) by means of HPLC with UV detection even at micrograms/l concentrations. The clean-up procedure of samples involves the use of strong anionic-exchange cartridges (SAX) for solid phase extraction (SPE). In order to improve the reproducibility of the retention time of MA (CV < 1%) and to obtain an adequate separation of MA from interferents, a high performance reverse-phase column (250 x 4.6 [I.D.] mm, 3 microns) is used and a careful control of the temperature (25 degrees C) is made. Also, a column-switching technique is applied to the chromatographic system in order to eliminate the highly retained peaks from the analytical column. The isocratic run is performed at a constant flow rate of 0.7 ml/min; the mobile phase consists of water: methanol: acetic acid (93.5:5.5: 1, v/v) and the UV detector is set at 259 nm. Under these conditions, MA elutes at 21.5 min and a single analysis takes 25 min; the detection limit (at a signal-to-noise ratio of 3) is 3 micrograms/l in urine, when a 200 microliters aliquot of the extract is injected in the analytical apparatus. The recovery of the clean-up procedure is > 90%; both the intra-assay and the inter-assay coefficients of variation are < 4%. The method has been applied to smokers and nonsmokers, subjects occupationally unexposed to benzene; the results showed a statistically significant difference between the two groups. Also, a close correlation was found between urinary excretion of MA measured with this method and environmental concentration of benzene in a population of workers occupationally exposed to low levels of this solvent.

Air Pollutants, Occupational↗
PubMedDate not supplied

[Polythelia as a sign of other congenital malformations: a clinical example].

The authors describe the clinical history of a girl with severe chronic constipation due to anterior ectopic anus, associated with supernumerary nipples. The authors underline the importance of possible associations between supernumerary nipples and other congenital anomalies.

Abnormalities, Multiple↗
PubMedDate not supplied

[Intestinal resection in children: personal experience and suggested follow-up. Preliminary results].

In the paediatric field cases of patients subjected to massive intestinal resection (M.I.R.) are more and more frequent; this survival of individuals with a small intestine shorter than 30 centimeters is not to be considered exceptional. Without going as far as such extreme limits of short residual intestine, intestinal resections contributed to create a new pathology represented by those patients who, once they have been subjected to particularly extended intestinal resections, need a particularly responsible nutritional therapy, sometimes with very long hospitalizations. The present study is to appraise the nutritional parameters and the residual absorption capacity of a group of patients in pediatric age subjected to intestinal resection, in order to draw up a record enabling to monitor, as time goes on, the intestinal functionality of those patients and to observe as early as possible the consequences of an alteration of intestinal physiology while creating the premisis for appropriate measures of nutritional supplementing.

Anthropometry↗
PubMedDate not supplied

[Massive intestinal resection in the newborn: nutritional and feeding problems].

Authors present their experience about nutritional treatment of short bowel syndrome in newborns. Their results seem to demonstrate that right approach to this problem is to start enteral nutrition as soon as possible, using mainly human milk and polimeric nutritional solutions. There are several experimental evidences that this kind of nutritional approach promote intestinal adaptation following massive intestinal resections.

Female↗
PubMedDate not supplied

[The measurement of a benzene metabolite, urinary S-phenylmercapturic acid (S-PMA), in man by HPLC].

Benzene is a widely used solvent, currently present in the industrial environment at concentrations in the order of ppm. A valid method of biological monitoring that is easy to perform is needed for assessing occupational exposures. Benzene is metabolized in the body by microsomal cytochrome P-450 mono-oxygenase system into benzene epoxide. Benzene epoxide is metabolized along three different pathways which end in the excretion of trans, trans muconic acid, S-phenyl-mercapturic (S-PMA) and different phenols. A new method has been developed to evaluate urinary S-PMA of subjects exposed to benzene. Human urine is acidified with HCl to PH 1 and passed through a Sep-Pak C18 cartridge. The cartridges are washed with diluted HCl and a mixture of water/methanol/acetic acid and then eluted with acidified chloroform. The eluate is dried and reconstituted with a buffer phosphate, then passed through an anionic exchange cartridge (SAX) which is washed with diluted buffer and diluted HCl. S-PMA is recovered by eluting with concentrated buffer and is transformed into S-phenyl-cysteine. Finally, S-phenyl-cysteine is detected by HPLC connected with a fluorescence detector (wavelengths: excitation 330 nm, emission 440 nm) after derivatization with o-phthalaldehyde (OPA) and 2-mercapto-ethanol (MCE). The detection limit of the method is about 0.5 micrograms/l, the recovery of S-PMA is 90.0% and the variation coefficient is 3.8%. The method was checked on urine samples of 8 male non-smokers and 10 smokers: median values of 1.3 and 9.2 micrograms/g creatinine respectively of S-PMA were obtained. A further analysis on urine samples of 66 occupationally exposed workers (smokers and non-smokers) revealed a median value of S-PMA of 46.6 micrograms/g creatinine, compared with a median environmental benzene exposure of 1.99 mg/m3. These results suggest that S-PMA can be regarded in the future as a useful indicator for monitoring individual and collective low-level benzene exposure.

Acetylcysteine↗
PubMedDate not supplied

[Syncopal fainting episodes and gastroesophageal reflux].

Fainting syncopal events are caused by a transient functional neuronal paralysis. Reflex syncope happens for brainstem involving mediated by peripherical afferents. Sometimes gastroesophageal reflux (GER) has been implicated in the development of obstructive apnea. Gastroesophageal reflux, despite the absence of a clinical history of vomiting and regurgitation, is observed in a significant proportion of infants presenting with ALTE (Apparent Life Threatening Event): an episode characterized by some combination of apnea, color change, marked change in muscle tone, choking or gagging. Though a cause-and-effect relationship between GER and the development of ALTE remains to be established a possible direct relationship between oesophageal acidification and the onset of alterations in cardiopulmonary function and impairment of consciousness can be hypothesized. We refer the case of two female infants that developed recurrent ALTE(s) characterized by paleness, change in muscle tone and loss of consciousness. The infants resulted affected respectively by a mild and severe gastroesophageal reflux (score: 40, > 50); in one case an episode of GER was recorded by the intraoesophageal pH-monitoring during a syncopal episode. The treatment with antiacid drugs was effectual and the infants did not present ALTE(s). The cases presented are in favour of a routine search of gastroesophageal reflux in infants presenting with one or recurrent ALTE(s). The identification of these infants will permitt to develop a correct strategy of treatment.

Age Factors↗
PubMedDate not supplied

CG5/Dx human breast cancer cell line: characterization of a new doxorubicin-resistant variant.

By continuous exposure of CG5 human breast cancer cell line to increasing doxorubicin (Dx) concentrations, a multidrug-resistant (MDR) subline (CG5/Dx) was obtained. The resistant variant showed P-glycoprotein (P-gp) expression and a lower intracellular doxorubicin level than the parental cells. CG5/Dx cells were 19.4 fold more resistant to Dx than CG5 cells and showed a cross-resistance to some structurally related and unrelated compounds. Differences in kinetics, biological and ultrastructural features between the two cell lines were investigated. The CG5/Dx cells grew more slowly, produced higher CEA levels and showed a reduced progesterone receptor (PgR) content than the parental cells. Ultrastructural studies revealed differences involving, polyribosomes, rough endoplasmic reticulum, [mitochondria] and cytoskeleton.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

[Indoor pollution and biological monitoring of volatile organic compounds (VOC)].

Indoor air is a complex mixture of chemicals and airborne particles. Volatile Organic Compounds (VOC), a broad class of chemicals including diverse compounds such as Aldehydes, Terpenes, Aromatic and Aliphatic Hydrocarbons and Halogenated Volatile Organics, are an important category of indoor air pollutants. The evaluation of exposure to low doses of Chloroform and Benzene through the measurement of Chloroform and Benzene in urine was performed. Results show that biological monitoring may be helpful in indoor environmental studies in non occupational situations.

Air Pollution, Indoor↗
PubMedDate not supplied

[Technical note: proposal of a routine method of accurate measurement of urinary trans,trans-muconic acid].

A method for routine measurement of urinary trans,trans-muconic acid. A method is proposed which allows the accurate determination of urinary trans,trans-muconic acid (Ma) by HPLC with UV detection. Sample pretreatment consists of a first purification on strong anionic exchange (SAX) cartridges followed by extraction on "end capped" reversed-phase (C18-EC) ones. Purified samples are directly injected onto a chromatographic column (C18, 150 x 4.6 mm I.D., 3 microns) which is eluted with water: methanol: acetic acid (97:2:1, v/v) mixture followed by a "spike" of acetonitrile. The retention time of MA is 15 min, the coefficient of variation is lower than 3%, the limit of detection is 7 micrograms/l. The method seems suitable for accurate biological monitoring of subjects exposed to benzene.

Chromatography, High Pressure Liquid↗