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Biomedical subjects

F Guerrini

Publications and source records attributed to F Guerrini.

At least 19 recordsLinked to original sources

Chemical and biochemical parameters of cultured diatoms and bacteria from the Adriatic Sea as possible biomarkers of mucilage production.

Bacteria and diatom strains from the Adriatic Sea were investigated, under standard and altered environmental conditions, for carbohydrate production and for the presence of specific biomarkers. Algae from P-depleted cultures showed an increase in extracellular carbohydrate production, a significantly lower chlorophyll a content and unchanged total lipid levels. However, the fatty acid composition of algal cultures was severely affected by low P levels, in that, total saturated and monounsaturated fatty acids increased and total polyunsaturated fatty acids decreased. Marine heterotrophic bacteria resulted enriched by 4 to 6 orders of magnitude in mucilage samples respect to surrounding seawater, unlike other groups of bacteria such as the non-halophylic heterotrophs. The major fatty acids detected in bacteria were 16:0 and 18:1n-7; the uneven fatty acids 17:0i, 17:0 and 17:1 also constituted an important component of various strains and, as a result, the total monounsaturated fraction represented the main component of total fatty acids. All the mucilage samples analysed shared the same general fatty acid composition features with a high amount of saturated components, especially 16:0; typical marine polyunsaturated fatty acids, such as 20:5n-3 and 22:6n-3, were found at very low levels. With regard to the sterol composition, the analysed algal species and bacteria showed that different compounds prevailed in the different species, and under P-deprivation sterol distribution resulted differently affected in the various algal species. In mucilage samples an overall prevalence of cholesterol was observed and, among 4alpha-methylsterols, constantly present, dinosterol prevailed in all samples. Vibrational IR spectroscopic analyses confirmed the main results obtained with the GC analysis: a higher unsaturation degree in nutrient replete diatom cultures than in P-depleted ones, a lower amount of P-containing compounds in the latter, bacterial lipid profiles with a high amount of free carboxylic acids and/or ketones and a low unsaturation degree and, finally, mucilage samples with a very low unsaturation degree. All these results allowed some speculations on the involvement of the various microbial and phytoplankton components in mucilage genesis.

Bacteria↗

Significant co-expression of WT1 and MDR1 genes in acute myeloid leukemia patients at diagnosis.

A high expression of Wilms' tumor gene (WT1) in acute myeloid leukemia (AML) seems to correlate with a poor outcome and its increased levels can be predictive of an impending relapse. WT1 has been shown in vitro to interact with the promoter of the MDR1, a gene involved in the multidrug resistance phenomenon. The aim of this study was to measure, by real-time polymerase chain reaction, levels of WT1 and MDR1 expression, in order to find a possible association between these genes, in a series of 50 newly diagnosed AML cases. Twenty-five percent of patients carried very high (>75 degrees percentile) MDR1- and 23.3%WT1-mRNA levels. Interestingly, high levels of WT1 were significantly correlated with correspondent high levels of MDR1 gene. Nevertheless, the co-expression of these genes did not significantly influence the complete response rate to the induction therapy. Reported data confirm the existence of a co-expression of WT1 and MDR1 genes even in vivo; this may be relevant because one consequence could be the positive selection by chemotherapeutic regimens of cells with higher MDR1 levels already present before treatment. Thus, the association between these genes could suggest avoiding the use of drugs involved in the multidrug resistance (MDR) phenomenon in patients carrying high levels of WT1 at diagnosis.

Adult↗

Quantitative molecular evaluation in autotransplant programs for follicular lymphoma: efficacy of in vivo purging by Rituximab.

The main aim of this paper was to compare results of Genescan and real-time PCR methods in order to detect contamination in harvests from patients with follicular lymphoma. The secondary goal was to evaluate the efficacy of Rituximab as an in vivo purging agent. A total of 23 patients had been treated with CHOP followed by either high-dose therapy (12 patients) or high-dose plus Rituximab (11 patients), both followed by autologous transplantation. Results show that 86% of harvests from patients treated with Rituximab were PCR-negative compared to 14.3% from controls. Real-time PCR was more sensitive than Genescan PCR; quantitative analysis revealed a correlation between the amount of contamination in the harvests and relapse after transplantation. Whereas all patients reinfused with negative aphereses achieved complete remission and showed a significantly better 5-year PFS (100%) compared to those reinfused with contaminated samples (41%), a very low amount of contamination does not appear to negatively affect outcome, suggesting that determination of a cutoff in the contamination level of harvests could be useful. Results suggest that real-time PCR is superior to Genescan PCR to select transplantable harvests and confirm the ability of Rituximab as an in vivo purging tool for follicular lymphoma.

Adult↗

The clinical relevance of the expression of several multidrug-resistant-related genes in patients with primary acute myeloid leukemia.

Multidrug resistance (MDR) is a complex phenomenon that includes the expression of many different genes regulating drug transport or metabolism, cellular repair or detoxification mechanisms. The co-expression of several genes could be at the basis of the resistant phenotype in vivo. In order to test a possible prognostic role of the expression and co-expression of several MDR-related genes (MDR1, topoisomerase IIalpha, topoisomerase IIbeta, MRP, GSTpi, LRP), 35 patients affected by acute myeloid leukemia (AML) were tested by RT-PCR assays. In our series, topoisomerase IIbeta was significantly co-expressed with MRP (p = 0.05), GSTpi (p = 0.017) and LRP (p = 0.005). GSTpi was co-expressed with LRP (p = 0.03) and MRP (p = 0.007); on the other hand, 53.8% of patients were LRP and MRP-positive (p = 0.02). The PCR-positivity did not differ according to biological/clinical characteristics of patients, including age; this latter was the only parameter conditioning the response and overall survival. Neither the expression nor the co-expression of the tested genes was significantly correlated with the response to the induction treatment and long-term outcome.

Adult↗

Surgical treatment of abdominal aortic aneurysms associated with aortic valve incompetence: strategies and outcomes.

BACKGROUND: The exact incidence of associated aortic valve incompetence (AVI) and abdominal aortic aneurysm (AAA) in the general population is not known. In recent years, we have observed this association with increasing frequency. This observation is probably due to the extensive preoperative screening of the cardiac and vascular status of patients who are candidates for surgical procedures. The choice of the optimal surgical strategy is needed to achieve low operative morbidity and mortality. The present study reviews our experience with a subset of patients suffering the association of AVI and large AAA. Surgical strategy, clinical management and outcome are presented. METHODS: Between January 1982 and May 2000, 76 patients with the association of AAA and AVI have been evaluated in our institution. Forty-four patients have been treated for both AAA and aortic valve (AV) regurgitation. These patients have been divided into three groups on the basis of the surgical strategy adopted. Group 1: combined procedure (16 patients); group 2: AAA repair prior to AV surgery (nine patients); group 3: AV surgery prior to aneurysm repair (19 patients). RESULTS: Hospital mortality was 4.5% (two patients); overall mortality was 6.8% (three patients). CONCLUSIONS: In patients with AAA and AVI, an accurate and complete preoperative evaluation is essential. Surgical strategy should be individualized on the basis of the cardiac preoperative status.

Adult↗

Noninvasive tests for risk stratification in major vascular surgery.

BACKGROUND: The predictive values of noninvasive tests versus perioperative cardiac events in patients undergoing major vascular surgery has not been definitively established. PATIENTS AND METHODS: According to clinical markers and left ventricular function at rest, 188 patients were assigned to the following groups: 40 low, 115 moderate and 33 high risk. They were then randomly submitted to dipyridamole (n = 64), dobutamine (n = 63) stress echocardiography and dipyridamole perfusion scintigraphy (n = 61). RESULTS: No events were observed in low-risk patients, whereas 12 (10.4%) and 8 (24%) events in moderate- and high-risk categories occurred, respectively. Only the high-risk category, as a predictive variable, was significantly related to the onset of cardiac complications (p < 0.05). A positive dipyridamole/dobutamine stress test was related to cardiac events, but multivariate analysis showed that only severity and extent of ischemia were the best predictors of events (p < 0.01 for dipyridamole and p < 0.005 for dobutamine). The presence of reversible, but not fixed, perfusion defects at scintigraphy was significantly related to perioperative events; at multivariate analysis, only > 3 reversible perfusion defects represented a strong predictor of events (p < 0.05). CONCLUSIONS: Among subjects undergoing major vascular surgery, severity and extent of ischemia during dipyridamole/dobutamine stress echocardiography and presence of > 3 reversible perfusion defects are strong predictors of cardiac events, particularly in moderate-risk category of patients.

Aged↗

The role of molecular monitoring in autotransplantation for non-Hodgkin's lymphoma.

Seventy-two patients with non-Hodgkin's lymphoma were evaluated for the presence of molecular markers (IgH, bcl-1, bcl-2 rearrangement) on bone marrow, at diagnosis and after PBSCT, and on harvests in order to find a possible predictive role of minimal residual disease on treatment outcome. At diagnosis, 41 (59%) out of 69 available bone marrows showed molecular involvement. Fifty-six percent of leukaphereses were involved, mainly indolent lymphoma (P = 0.001) or advanced disease (P = 0.01). Ex vivo purging cleared only one stem collection out of 31 PCR-positive leukaphereses. Aggressive lymphomas showed both a longer overall survival (OS) (P = 0.03) and relapse-free survival RFS (P = 0.02) when transplanted with unpurged stem cells, whereas indolent NHL survival was not influenced by ex vivo purging. Twenty out of 26 samples taken during follow-up had bone marrow involvement at diagnosis. Of these, 15 cleared their bone marrow; both OS and RFS were significantly longer in the PCR-negative cases (P = 0.05 and P = 0.005). At 1 year after PBSCT, 75% of patients were PCR negative, with 50% molecular remissions; the relapse rate was 55% for patients still PCR positive vs 29% for those who were PCR negative. Thus, after high-dose chemotherapy, close molecular monitoring of MRD using qualitative PCR techniques seems to represent a reliable prognostic indicator.

Adolescent↗

Prognostic value of dipyridamole stress echocardiography in hypertensive patients with left ventricular hypertrophy, chest pain and resting electrocardiographic repolarization abnormalities.

BACKGROUND: Hypertension is a major cardiovascular risk factor in the development of coronary artery disease (CAD); therefore, evaluating the presence of CAD is a primary clinical goal. However, the noninvasive tests that are commonly used have poor diagnostic specificity, particularly in patients with left ventricular hypertrophy. OBJECTIVES: To assess the prognostic value of dipyridamole stress echocardiography (DET) for ischemic events in a subset of patients with hypertension with left ventricular hypertrophy, chest pain and resting electrocardiographic repolarization abnormalities. PATIENTS AND METHODS: Eighty-two patients (48 men and 34 women; average age 65+/-7.2 years with left ventricular hypertrophy documented echocardiographically (left ventricular mass index greater than 50 g/h(2.7)), and resting ST segment shift of 0.1 mV or more from baseline at 80 ms after J point in at least two contiguous leads, were submitted to DET according to high-dosage protocol and coadministered with atropine. RESULTS: The follow-up period was 25.11+/-8.3 months. The stress test produced positive results in 30 patients (36.5%); 16 (53%) and three (5%) cardiac events occurred in positive and negative stress test groups, respectively. At multivariate analysis, only positive DET response (P=0.000002), left ventricular mass index (P=0.028) and a family history of CAD (P=0.037) were independent predictors. The two-year event-free survival rates were 95% and 47% (log-rank 21.093, P=0.00001) for negative and positive stress test results, respectively. CONCLUSIONS: DET is a useful tool in the prognostic assessment of coronary events in this particular subgroup of patients with hypertension.

Aged↗

A primary intracavitary right atrial neurilemoma.

Primary cardiac neurilemoma, a benign tumor, is extremely uncommon. To our knowledge only eight cases have been reported in the literature. We report a case of a 72-year-old man who presented with complaints of progressive shortness of breath and chest pain, seven years after a right nephrectomy for renal adenocarcinoma. An intra-right atrial tumor was surgically removed; the lesion was found to be a neurilemoma of the right atrium. This case report describes the surgical removal and rarity of neurilemomas, their predisposition to be right-sided in the heart and their coincidental association with other types of cancer.

Adenocarcinoma↗

Correlation between left atrial size, prothrombotic state and markers of endothelial dysfunction in patients with lone chronic nonrheumatic atrial fibrillation.

Atrial fibrillation is associated with a prothrombotic state and endothelial dysfunction. To understand whether the prothrombotic state was correlated with endothelial dysfunction and whether the latter was related to atrial dimension (endocardial damage), we studied systemic hemocoagulative activity and markers of endothelial dysfunction in 45 patients with chronic nonrheumatic atrial fibrillation and in 35 controls. We assessed fibrinogen, antithrombin III, protein C, markers of platelet activation (platelet factor 4 and beta-thromboglobulin) as markers of fibrinolysis, and D-dimer, tissue plasminogen activator, plasminogen activator inhibitor, von Willebrand's factor and soluble thrombomodulin as endothelial dysfunction. Plasma fibrinogen (P<0. 005), platelet factor 4 (P<0.001), thromboglobulin (P<0.001), D-dimer (P<0.03), tissue plasminogen activator (P<0.006), plasminogen activator inhibitor (P<0.04) and both von Willebrand's factor (P<0.0001) and soluble thrombomodulin (P<0.03) were significantly higher in the patients than in the controls. Positive significant linear correlations were found between fibrinogen and markers of endothelial dysfunction and left atrial volume and fibrinogen or markers of endothelial dysfunction. These findings confirm that chronic nonrheumatic atrial fibrillation is associated with a prothrombotic state but also suggest that there is a correlation between endothelial dysfunction, coagulation factors and left atrial dimension.

Aged↗

High sensitivity bioassay of paralytic (PSP) and amnesic (ASP) algal toxins based on the fluorimetric detection of [Ca(2+)](i) in rat cortical primary cultures.

A high sensitivity bioassay able to recognise small amounts of paralytic and amnesic toxins in algal acetic extracts is described. The method is based on the measure of intracellular [Ca(2+)](i) in primary cultures of rat cortical neurones preloaded with Fura-2 and submitted to electrical field stimulation. Under normal conditions the basal [Ca(2+)](i) level was about 50-100 nM and was nearly doubled during the peaks induced by trains of electrical pulses at 10 Hz for 10 s. Saxitoxin (STX) 3.5 nM and tetrodotoxin (TTX) 24 nM halved the peaks height without affecting basal [Ca(2+)](i). Conversely, domoic acid increased the basal [Ca(2+)](i) (EC(50)=3. 7 microM) and decreased the calcium peaks (EC(50)=7.3 microM). CNQX (a competitive antagonist of AMPA/KA receptors) at 10 microM shifted to the right by a factor of 3 the concentration-response curves of domoic acid. The extracts of non-toxic algae were well tolerated by up to 10 microg protein/ml, whereas extracts of Alexandrium lusitanicum at 1-4 microg protein/ml reduced [Ca(2+)](i) peaks and increased basal calcium levels. This toxic effect of A. lusitanicum was unexpected since parallel HPLC analysis showed only the presence of gonyautoxins, known to act like saxitoxin. Therefore, the bioassay on rat cortical neurones revealed a complex composition of the toxins present in A. lusitanicum. The relevance of fluorimetric detection of [Ca(2+)](i) in primary neuronal cultures in the evaluation of algal risk is stressed.

Algal Proteins↗

Rana/Pol III: a family of SINE-like sequences in the genomes of western Palearctic water frogs.

The highly repetitive Rana/Pol III family consists of short, tandemly arrayed sequences, scattered throughout the genomes of Palearctic green water frogs. The repeat unit is about 250 bp in length and is a composite element: it contains a SINE-like retroposon with a tRNA structure, flanked by two short direct repeats, and the occurrence of two internal repeats gives evidence that an additional transposition event may have inserted a segment within the already transposed element. Rana/Pol III family is present in the genomes of Rana lessonae, R. ridibunda, and their hybrid form R. esculenta, as well as in R. shqiperica. R. epeirotica, R. cretensis, and the Italian taxon. These sequences are also present in the Iberian R. perezi, although less abundant, but appear to be lacking in the north African species R. saharica. The distribution of Rana/Pol III in the genomes of Palearctic green frogs is in agreement with the phyletic history based on genetic data. The evolutionary pattern proposed for the genus Rana enables us to suppose that the hybridogenetic mechanism is one of the factors accounting for the possible horizontal transfer of Rana/Pol III elements from the central-north Europe species to R. perezi.

Africa, Northern↗

Genetic analysis of leishmania parasites in Ecuador: are Leishmania (Viannia) panamensis and Leishmania (V.) Guyanensis distinct taxa?

In the course of an epidemiologic survey in Ecuador, the following collection of Leishmania stocks was isolated: 28 from patients with clinical signs of leishmaniasis, 2 from sloths, 1 from a dog, and 4 from sand flies. For genetic characterization of these stocks, multilocus enzyme electrophoresis (MLEE) and random amplified polymorphic DNA (RAPD) were used. Twenty six of the 35 stocks were identified as either Leishmania (V.) panamensis or L. (V.) guyanensis, 2 stocks were identified as L. (V.) braziliensis, the 2 stocks from sloths showed specific genotypes, and 5 stocks were characterized as hybrids between L. (V.) braziliensis and L. (V.) guyanensis. These data show that genetic diversity of Leishmania in Ecuador is high and that L. (V.) panamensis/guyanensis is the dominant group in this country. The genetic analysis questioned the distinctness between the two species L.(V.) panamensis and L. (V.) guyanensis, since MLEE and RAPD data did not indicate that L. (V.) panamensis and L. (V.) guyanensis correspond to distinct monophyletic lines. Population genetic analysis performed on the L. (V.) panamensis/guyanensis group favors the hypothesis of a basically clonal population structure.

Animals↗

Genomes of two water frog species resist germ line exclusion in interspecies hybrids.

Abundant natural interspecies hybrids between the European water frog Rana ridibunda and at least three other taxa reproduce hemiclonally, by hybridogenesis: the non-ridibunda genome is excluded in the germ line before meiosis, and the unrecombined ridibunda genome is transmitted to haploid gametes. In contrast, natural hybrids between Rana ridibunda and either of two Balkan species (Rana shqiperica and Rana epeirotica) do not show such genome exclusion. This plausibly results from failure of Balkan Rana ridibunda genomes to "induce" such exclusion in the germ line of hybrids, from "resistance" of Rana shqiperica and Rana epeirotica genomes to such exclusion in hybrids with an "inducing" Rana ridibunda genome, or both. We tested the second hypothesis by examining lampbrush chromosome patterns in oocytes of hybrids that in the soma contain one "inducing" ridibunda genome and one genome of either of the two Balkan species. Several lampbrush chromosome markers (e.g., presence and location of certain giant loops and conspicuousness and width of centromeres) discriminate sets of Rana ridibunda chromosomes from those of Rana shqiperica and Rana epeirotica. Based on such markers, nine diploid female hybrids between Rana ridibunda or Rana esculenta from natural hybridogenetic lineages (Rana ridibunda x Rana lessonae, making ridibunda gametes) from central Poland and either Rana shqiperica or Rana epeirotica each contained both parental genomes in primary oocytes; the bivalents showed reduced numbers of chiasmata compared with parental species. It follows that none of these hybrids was hybridogenetic. This conclusion is confirmed, for two hybrids between Rana epeirotica and either Rana ridibunda or Rana esculenta, by protein electrophoretic comparison of somatic tissues with primary oocytes, all of which evidenced allelic markers of both parental species. Because Rana ridibunda genomes that are known to induce germ line genome exclusion when combined in hybrids with Rana lessonae genomes were used, these data provide the first compelling evidence for resistance of Rana shqiperica as well as Rana epeirotica genomes to such exclusion.

Animals↗

Molecular characterization of a centromeric satellite DNA in the hemiclonal hybrid frog Rana esculenta and its parental species.

Hybrid water frogs Rana esculenta reproduce by hybridogenesis: one parental genome (of Rana lessonae) is excluded in the germ line, the other (of Rana ridibunda) is clonally transmitted to haploid gametes. The two parental species differ in that the amount of centromeric heterochromatin revealed by differential staining is much higher in Rana ridibunda. An abundant, tandemly arrayed, centromeric satellite DNA, designated RrS1, is revealed in Rana ridibunda genomes by the restriction endonuclease Stul, which generates a major repetitive sequence fragment of 300 and a minor one of 200 bp. This AT-rich (68%) satellite family is located at the centromeres of the five largest chromosomes (1-5) and of a medium to small heterobrachial one (8 or 9); it thus constitutes only part of the centromeric heterochromatin that characterizes all Rana ridibunda chromosomes. RrS1 represents about 2.5% of the genome of Rana ridibunda; it may represent as little as 0.2% of the genome of Rana lessonae, and cannot be detected in Xenopus laevis frogs or Salamandra salamandra and Triturus carnifex salamanders. Segments of the satellite sequence are similar to sequences of yeast centromeric DNA element CDEIII and of the mammalian CENP-B box. A role for RrS1 and other centromeric satellite DNAs in the germ line genome exclusion of the hybridogenetic frog hybrids, although suggested, has not yet been demonstrated.

Animals↗