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Biomedical subjects

L Furci

Publications and source records attributed to L Furci.

29 records · Page 2Linked to original sources
PubMed1990

Molecular cloning, primary structure, and expression of the human platelet/erythroleukemia cell 12-lipoxygenase.

The major pathway of arachidonic acid metabolism in human platelets proceeds via a 12-lipoxygenase enzyme; however, the biological role of the product of this reaction, 12-hydro(pero)xyeicosatetraenoic acid [12-H(P)ETE], is unknown. Using a combination of the polymerase chain reaction and conventional screening procedures, we have isolated cDNA clones encoding the human platelet/human erythroleukemia (HEL) cell 12-lipoxygenase. From the deduced primary structure, human platelet/HEL 12-lipoxygenase would encode a Mr 75,000 protein consisting of 663 amino acids. The cDNA encoding the full-length protein (pCDNA-121x) under the control of the cytomegalovirus promoter was expressed in simian COS-M6 cells. Intact cells and lysed-cell supernatants were able to synthesize 12-H(P)ETE from arachidonic acid, whereas no 12-H(P)ETE synthesis was detected in mock-transfected cells. A single 2.4-kilobase mRNA was detected in erythroleukemia cells but not in several other tissues and cell lines evaluated by Northern blot analysis. Comparison of the human platelet/HEL 12-lipoxygenase sequence with that of porcine leukocyte 12-lipoxygenase and human reticulocyte 15-lipoxygenase revealed 65% amino acid identity to both enzymes. By contrast, the leukocyte 12-lipoxygenase is 86% identical to human reticulocyte 15-lipoxygenase. Sequence data and previously demonstrated immunochemical and biochemical evidence support the existence of distinct 12-lipoxygenase isoforms. The availability of cDNA probes for human platelet/HEL cell 12-lipoxygenase should facilitate elucidation of the biological role of this pathway.

Amino Acid Sequence↗
PubMed1989

Induction of prostacyclin receptor expression in human erythroleukemia cells.

We have identified both high-affinity (KD = 36 +/- 3 nM) and low-affinity (KD = 2.1 +/- 0.8 microM) prostacyclin (PGI2)-receptor sites on human erythroleukemia (HEL) cells using the radiolabelled prostacyclin analogue. [3H]iloprost. The addition of the phorbol ester, TPA, to the culture medium caused a 5-10-fold increase in the number of both the low- and the high-affinity sites, without any change in their affinity constants. Iloprost stimulated HEL cell membrane adenylate cyclase activity 5-fold. This stimulation was potentiated in the presence of GTP, indicating a conventional PGI2 receptor-G2-adenylate cyclase system. HEL cells represent a source of prostacyclin receptor mRNA which may be of value in expression cloning of this receptor.

Adenylyl Cyclases↗
PubMed1988

Increased urinary excretion of thromboxane B2 and 2,3-dinor-TxB2 in cyclosporin A nephrotoxicity.

Cyclosporin A (CsA) administration to rats is associated with a selective increase in urinary excretion of immunoreactive thromboxane B2 (i-TxB2), the stable breakdown product of TxA2. The exaggerated synthesis of TxA2 may play a role in the reduction of glomerular filtration rate (GFR) observed both in animals and humans undergoing CsA treatment. The present study was designed to get further insight into the origin of the abnormal i-TxB2 urinary excretion. Rats given orally CsA (50 mg/kg/day) for 30 days had a significant increase in the urinary excretion of both 2,3-dinor-TxB2 and TxB2 measured by technique of capillary column gas chromatography-negative ion chemical ionization mass spectrometry (HRGC-NICIMS). Urinary TxB2 is more likely to reflect the renal synthesis of the parent compound, whereas 2,3-dinor-TxB2 is considered to reflect the amount of TxB2 formed in the circulation. Experiments in isolated perfused kidney (IPK) taken from animals given CsA for 30 days showed a lower percentage increase in urinary TxB2 over vehicle treated animals. Moreover in IPK the ratio 2,3-dinor-TxB2/TxB2 was lower than in vivo. The amount of i-TxB2 detectable in serum of animals given CsA was not different from that of control animals. In contrast, isolated glomeruli taken from rats given CsA had an increase in their TxA2 synthesis measured as i-TxB2 in the supernatants. Ultrastructural studies on kidney specimens from animals given CsA showed a focal glomerular endothelial damage together with a marked infiltration of blood borne cells of monocyte-macrophage type in the glomerular tuft. In contrast, kidney specimens taken from IPK preparations were devoid of inflammatory cells. In vitro CsA did not interfere with platelet arachidonic acid (AA) metabolism as shown by a normal i-TxB2 generation in vitro by rat platelet-rich plasma (PRP) exposed to CsA and then challenged with AA or ADP. Similarly isolated glomeruli and isolated proximal tubules from normal rats when challenged with CsA in vitro converted AA into TxA2 normally. It is suggested that the cause of the increased urinary excretion of 2,3-dinor-TxB2 is the consequence of intrarenal platelet and macrophage activation, probably triggered by the endothelial damage. The parallel increase in the urinary excretion of unmetabolized TxB2 is likely to reflect a concomitant activation of resident renal cell AA metabolism induced by CsA.

Animals↗
PubMed1987

Prognostic factors and effectiveness of treatment in acute renal failure due to multiple myeloma: a review of 50 cases. Report of the Italien Renal Immunopathology Group.

We studied 50 patients with myeloma acute renal failure to investigate possible prognostic factors and to evaluate the effectiveness of the various treatment schedules used. Renal failure was reversible 1 month after the onset in 50% of the patients considered. The patients treated with chemotherapy and plasma exchange recovered renal function more frequently (61% of the cases) than those treated only with chemotherapy (27%). The most important clinical prognostic factors were total proteins, serum creatinine values and myeloma type. Considering the histological findings, the prognosis correlated with the severity of the lesions and number of tubular casts. Survival at 1 year was higher in the patients who regained renal function than in those in whom renal function did not improve.

Acute Kidney Injury↗
PubMed1986

Cyclosporin-induced endothelial cell injury.

The administration of Cyclosporin-A (CyA) to animals and humans may induce an arteriolar damage. It has also been reported that CyA in some instances may cause an hemolytic uremic-like syndrome. This is a syndrome of vascular damage with thrombotic occlusions of the microcirculation. Endothelial injury is considered the first event in the pathogenetic cascade leading to hemolytic-uremic syndrome. We have used bovine aortic endothelial cells in culture to address the issue of CyA-induced arteriolar damage. Exposure of endothelial cells to different concentrations of CyA induced a time- and dose-dependent cell injury in vitro. The damage induced by CyA was characterized by an early cell detachment from culture substrate followed by cell lysis as documented by the increase in lactate dehydrogenase (LDH) and 51Cr release. Both detachment and lysis were negligible after short-term incubation of 1 microM CyA with endothelial cells. One micromolar CyA only induced lysis if incubations were prolonged above 6 hours. Ten and 50 microM CyA both induced marked endothelial cell detachment and lysis; lysis started 3 hours after incubation of endothelial cells with CyA and was maximal at the end of 24 hours incubation. CyA-induced injury was associated with dose- and time-dependent increase in prostacyclin and thromboxane A2 release by endothelial cells exposed to CyA independently from the concentrations of CyA used. CyA-induced generation of prostacyclin and thromboxane A2 was inhibited when the incubations were performed in the presence of aspirin (500 microM). These studies indicate that CyA exerts a direct cytotoxic effect on endothelial cells and might help in understanding the pathogenesis of CyA-induced vascular damage.

Animals↗
PubMedDate not supplied

Absence of rejection in cryopreserved saphenous vein allografts for hemodialysis.

Since November 1987, a total of 16 dialysis patients in the authors' Center, received a cryopreserved saphenous vein allograft (CSVA) as "third choice" vascular access. ABO and HLA-A-B compatibilities were determined but not considered. Saphenous veins were cryopreserved in liquid nitrogen for variable periods (1-6 mo), so that there was the opportunity to choose the most suitable in dimension. In February, 1989, a total of 13 patients retained a well-functioning access site, whereas three had died from causes unrelated to CSVA. Because rejection of venous allografts still is debated among angiologists, recipient T lymphocyte subsets (CD3-CD4-CD8 and CD4/8) were examined, as were lymphocytotoxic antibodies, before and on days 15 and 30 after implantation. No evidence of immunologic activation was found. Moreover, in 10 of 16 patients the surgeons subcutaneously implanted a fragment of CSVA, and an immunohistochemical study was carried out using an alkaline phosphatase-antialkaline phosphatase (APAAP) technique and a panel of monoclonal antibodies. Minimal infiltration of the outer layer of adventitia was found, mainly caused by monocyte macrophages (Leu M3+) with few T lymphocytes (CD3+). The authors conclude that rejection is not a major cause of failure in CSVA in dialysis patients.

Aged↗
PubMedDate not supplied

Heterogeneity in exposed uninfected individuals.

In spite of repeated exposures to HIV, some individuals remain seronegative and apparently uninfected. A variety of mechanisms potentially able to confer resistance to HIV infection, including cell-mediated and (unconventional) humoral immune responses, as well as mutations affecting receptors for virus entry have been considered and analysed. In this article, we want to discuss recent reports on specific immune responses and genetic factors potentially involved in mechanisms of protection, and to present some of our data relative to a cohort of people sexually exposed to HIV-1, but persistently seronegative. These EU (exposed uninfected) individuals can be distinguished from "normal" unexposed controls on the basis of significantly increased frequencies of a number of immunological parameters that might be considered "unconventional" correlates of HIV infection/protection. However, EU individuals are highly heterogeneous since the various unconventional immune responses considered can be present in all possible combinations. Aim of future research will be to ascertain the role of such immune responses in the maintenance of the protection state, or their secondary nature as signals of a particular kind of infection.

Genetic Variation↗
PubMedDate not supplied

Increased plasma levels of the C-C chemokine RANTES in patients with primary HIV-1 infection.

To investigate the role played by chemokines in the natural history of human immunodeficiency virus (HIV) infection, we measured the plasma levels of RANTES. MIP-1 alpha and MIP-1 beta in a cohort of patients with primary HIV-1 infection (PHI) followed longitudinally. The cohort included 17 patients with well-documented history of acute HIV syndrome within two months of the first observation. The mean plasma concentration of RANTES, but not that of MIP-1 alpha or MIP-1 beta, was significantly higher in patients with PHI (192.3 ng/ml) than in five HIV-seronegative controls (8.0 ng/ml) studied during the same time period. Treatment of blood with a cocktail of drugs preventing platelet activation, followed by high-speed centrifugation, reduced the levels of RANTES by approximately 2 logs both in patients and in controls, indicating that the bulk of RANTES was released by platelets, which are known to store this chemokine in their alpha-granules, in the immediate aftermath of blood drawing. No correlation was seen between the levels of RANTES and the number of HIV genome equivalents in plasma. These data suggest that large amounts of pre-formed RANTES are stored in platelets and, possibly, in other blood cells during the early phases of HIV infection. The possible role of this HIV-suppressive chemokine in the control of viral replication during PHI remains to be established.

Chemokine CCL5↗