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Biomedical subjects

L Pardini

Publications and source records attributed to L Pardini.

At least 19 recordsLinked to original sources
PubMed2006

Modì: a new mobile instrument for in situ double-pulse LIBS analysis.

Laser-induced breakdown spectroscopy (LIBS) is a promising technique for in situ elemental analysis. A new mobile instrument for LIBS analysis, developed in a collaboration between Marwan Technology s.r.l. and the Applied Laser Spectroscopy Laboratory in Pisa, is presented, and some applications of it and results from it are outlined. The innovative experimental set-up, based on the use of two suitably retarded laser pulses and a standardless analysis procedure, which overcomes problems related to matrix effects, greatly improves the potential of this technique for accurate quantitative analysis.

Journal Article↗
PubMed2005

Human intestinal circadian clock: expression of clock genes in colonocytes lining the crypt.

Biological clock components have been detected in many epithelial tissues of the digestive tract of mammals (oral mucosa, pancreas, and liver), suggesting the existence of peripheral circadian clocks that may be entrainable by food. Our aim was to investigate the expression of main peripheral clock genes in colonocytes of healthy humans and in human colon carcinoma cell lines. The presence of clock components was investigated in single intact colonic crypts isolated by chelation from the biopsies of 25 patients (free of any sign of colonic lesions) undergoing routine colonoscopy and in cell lines of human colon carcinoma (Caco2 and HT29 clone 19A). Per-1, per-2, and clock mRNA were detected by real-time RT-PCR. The three-dimensional distributions of PER-1, PER-2, CLOCK, and BMAL1 proteins were recorded along colonic crypts by immunofluorescent confocal imaging. We demonstrate the presence of per-1, per-2, and clock mRNA in samples prepared from colonic crypts of 5 patients and in all cell lines. We also demonstrate the presence of two circadian clock proteins, PER-1 and CLOCK, in human colonocytes on crypts isolated from 20 patients (15 patients for PER-1 and 6 for CLOCK) and in colon carcinoma cells. Establishing the presence of clock proteins in human colonic crypts is the first step toward the study of the regulation of the intestinal circadian clock by nutrients and feeding rhythms.

ARNTL Transcription Factors↗
PubMed2004

Robust incremental compensation of the light attenuation with depth in 3D fluorescence microscopy.

Summary Fluorescent signal intensities from confocal laser scanning microscopes (CLSM) suffer from several distortions inherent to the method. Namely, layers which lie deeper within the specimen are relatively dark due to absorption and scattering of both excitation and fluorescent light, photobleaching and/or other factors. Because of these effects, a quantitative analysis of images is not always possible without correction. Under certain assumptions, the decay of intensities can be estimated and used for a partial depth intensity correction. In this paper we propose an original robust incremental method for compensating the attenuation of intensity signals. Most previous correction methods are more or less empirical and based on fitting a decreasing parametric function to the section mean intensity curve computed by summing all pixel values in each section. The fitted curve is then used for the calculation of correction factors for each section and a new compensated sections series is computed. However, these methods do not perfectly correct the images. Hence, the algorithm we propose for the automatic correction of intensities relies on robust estimation, which automatically ignores pixels where measurements deviate from the decay model. It is based on techniques adopted from the computer vision literature for image motion estimation. The resulting algorithm is used to correct volumes acquired in CLSM. An implementation of such a restoration filter is discussed and examples of successful restorations are given.

Algorithms↗
PubMed2000

Tumor development and cytokine production by human colon tissues and carcinoma cell lines.

BACKGROUND AND OBJECTIVES: Solid tumors evade the host immunologic responses they initiate by unknown mechanisms. The authors investigated patterns of cytokine content in human colon carcinomas, colon cancer cell lines in vitro, and nude mouse xenografts from those lines in order to clarify those mechanisms. METHODS: Epithelial tumor cell lines were developed from specimens of human colon adenocarcinoma. Aliquots of these cells were then xenografted into female heterozygous BALB/c nu/+ immunologically deficient mice and serially passaged. Original tumors, cell lines, and resultant xenografts were then analyzed for histology/cytology and for levels of TGF-beta and TNF-alpha by enzyme linked immunoassay. RESULTS: Cytokine levels were elevated beyond baseline mucosal levels in original tumors and xenograft mouse tumors but not detectable in extracts from epithelial cultures. CONCLUSIONS: While the precise source of cytokine production remains unclear, these data suggest tumor/host interactions not found in pure epithelial cancer cells in culture.

Adenocarcinoma↗
PubMed1997

Intervention of transplantable human mammary carcinoma MX-1 chemotherapy with dietary menhaden oil in athymic mice: increased therapeutic effects and decreased toxicity of cyclophosphamide.

We investigated the effects of dietary menhaden oil on cyclophosphamide (CP) antineoplastic activity and its protective effect against CP toxicity. We found that dietary menhaden oil (HMO, 20% menhaden oil + 5% corn oil) enhanced the CP antitumor effect at the lowest dose tested (50 mg/kg) compared with the control group (LCO, 5% corn oil). Dietary HMO and CP treatment had a significant effect on the activities of tumor and liver microsomal cytochrome P-450 (CYP) over the controls. Activity of one of the key CP activating enzymes, CYP2B1 (which is similar to human CYP2B6), was significantly enhanced in the liver and tumor by the HMO diet, which could result in the formation of more pharmacologically active CP metabolites and, therefore, increased CP antitumor response. Moreover, the HMO diet exhibited a very significant protective effect against CP acute toxicity. The activity of the CP detoxifying enzyme aldehyde dehydrogenase (ADH) was significantly increased in the liver after HMO feeding; thus the observed protective effect of HMO feeding against CP toxicity may be partially the result of induction of ADH activity in the liver. In summary, our findings suggested that dietary menhaden oil can modulate ADH and CYP activities in a manner that may alter the metabolism of CP and, therefore, improve its therapeutic index by increasing its therapeutic effect and decreasing its toxicity.

Animals↗
PubMed1995

Dietary menhaden oil enhances mitomycin C antitumor activity toward human mammary carcinoma MX-1.

In the present study, we investigated the effects of high levels of dietary fish oil on the growth of MX-1 human mammary carcinoma and its response to mitomycin C (MC) treatment in athymic mice. We found that high levels of dietary fish oil (20% menhaden oil + 5% corn oil, w/w) compared to a control diet (5% corn oil, w/w) not only lowered the tumor growth rate, but also increased the tumor response to MC treatment. We also found that high levels of dietary fish oil significantly increased the activities of tumor xanthine oxidase and DT-diaphorase, which are proposed to be involved in the bioreductive activation of MC. Since menhaden oil is highly unsaturated, its intake caused a significant increase in the degree of fatty acid unsaturation in tumor membrane phospholipids. This alteration in tumor membrane phospholipids made the tumor more susceptible to oxidative stress, as indicated by the increased levels of both endogenous lipid peroxidation and protein oxidation after feeding the host animals the menhaden oil diet. In addition, the tumor antioxidant enzyme activities, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPOx), and glutathione S-transferase peroxidase (GSTPx), were all significantly enhanced by feeding a diet high in fish oil. MC treatment caused further increases in tumor lipid peroxidation and protein oxidation, as well as in the activities of CAT, SOD, GPOx, and GSTPx, suggesting that MC causes oxidative stress in this tumor model which is exacerbated by feeding a diet high in menhaden oil. Thus, feeding a diet rich in menhaden oil decreased the growth of human mammary carcinoma MX-1, increased its responsiveness to MC, and increased its susceptibility to endogenous and MC-induced oxidative stress, and increased the tumor activities of two enzymes proposed to be involved in the bioactivation of MC, that is, DT-diaphorase and xanthine oxidase. These findings support a role of these two enzymes in the bioactivating of MC and indicate that the type of dietary fat may be important in tumor response to therapy.

Animals↗
PubMed1994

Enhancement of the antineoplastic effect of mitomycin C by dietary fat.

In the present study, we investigated the effects of high dietary fat on the growth of MX-1 heterotransplanted in athymic mice and its response to mitomycin C (MC) treatment. We found that high fat intake (25% corn oil, w/w) significantly increased tumor growth, but at the same time it also increased the tumor response to MC treatment compared to the control low fat diet (5% corn oil, w/w). In the tumors from mice fed either low (5% w/w) or high (25% w/w) fat, MC treatment induced oxidative challenge, indicated by significantly increased tumor total superoxide dismutase, catalase, glutathione peroxidase, and glutathione S-transferase peroxidase activities, as well as increased tumor lipid peroxidation. On the other hand, glutathione reductase activity was inhibited by MC treatment. Some of the enzymes which are known to activate MC, such as cytochrome b5 reductase and DT-diaphorase, were also induced in the tumor by high dietary fat intake. The enzyme activities in hepatic tissues were also altered by dietary fat and MC treatment but to a lesser extent. We conclude that high dietary fat intake could enhance the chemotherapeutic effect of MC by increasing MC-activating enzyme activities. The observed increase in lipid peroxidation after MC treatment in MX-1 human mammary carcinoma implanted in the nude mice could result from the observed inhibited glutathione reductase activity. It is tempting to speculate that this might be another antineoplastic mechanism for MC in addition to its known role as a bioreductive alkylating agent. Alternatively, glutathione reductase may be a target for bioreductive alkylation.

Animals↗
PubMed1989

Effects of dietary fish oil on human mammary carcinoma and on lipid-metabolizing enzymes.

The growth rate of a human mammary carcinoma, MX-1, was significantly reduced in athymic "nude" mice fed fish oil. Tumors from the fish oil-fed animals also showed a greater sensitivity to two anti-neoplastic agents, mitomycin C and doxorubicin. Mitochondria were isolated from control livers, host livers and tumors from fish oil- and corn oil-fed animals, and increased levels of 20:5n-3 and 22:6n-3 were found in mitochondrial lipids in all three tissues from the fish oil-fed animals. To investigate the effect of dietary n-3 fatty acids on lipid metabolism, the activity of the acyl-CoA:carnitine acyltransferase and three acyl-CoA desaturases were measured. Carnitine acyltransferase activity toward all four acyl-CoA substrates tested was markedly increased in mitochondria from liver by feeding fish oil. In mitochondria from tumors, feeding fish oil resulted in an increased activity toward only 18:3n-3. These data suggest that fish oil may induce an increase in the oxidation of fatty acids. The delta 9-desaturase activity was decreased in microsomes from liver and tumor from fish oil-fed animals. However, both the delta 6 and delta 5 desaturases were increased in tumor and in control liver as a result of feeding fish oil. The delta 5 desaturase was not altered in microsomes from the host animals. The effect of fish oil on the delta 5 and delta 6 desaturases may involve alterations to metabolism of specific polyunsaturated fatty acids especially in the tumor tissue.

Acyltransferases↗
PubMed1986

Quantification of the parameters of the acoustic reflex in normal ears.

Measurement of the acoustic stapedial reflex parameters has proved to be a useful tool for evaluating the function of the acoustic-facial reflex. However, there is no agreement about the definitions of the parameters; moreover, most of the data have been obtained by manual measurement methods. The authors describe a computerized analytical method which permits the parameters to be measured according to the definitions and methods suggested by others and according to the new analytical method described, which is performed on the basis of the derivative of the stapedial reflex curve. The two methods are compared in 40 normal subjects.

Adolescent↗
PubMed1983

[The occurrence of nystagmus in sustained sinusoidal stimulation].

Twenty normal subjects have been submitted to a set of vestibular sinusoidal stimulations, the maximal acceleration per hemiperiod being constant. However the nystagmic response (number of beats per hemiperiod) was not constant, but increased during every single trial. The clinical consequences of this observation are discussed. In particular authors suggest that the classical damped sinusoidal stimulation test should be considered a semi-quantitative test.

Adolescent↗