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Biomedical subjects

G Guidi

Publications and source records attributed to G Guidi.

At least 73 records · Page 4Linked to original sources
PubMed1996

Effects of anticoagulants on lipoprotein(a) measurements with four commercial assays.

Lipoprotein(a) levels in plasma are considered an independent risk factor for atherosclerosis at different sites. Although Lp(a) measurements have recently gained interest in clinical laboratories, several problems are still unresolved. A potential source of pre-analytical variability lies in the treatment of the specimens, since it has been reported that values of several lipid quantities are lower when measured in plasma instead of serum. Lp(a) was measured in serum and in EDTA-treated, heparinised and citrated plasma from 15 healthy volunteers. Four analytical methods were used: two enzyme linked immunosorbent assays [ELISA] based on a polyclonal anti-apolipoprotein(a) antibody and a polyclonal anti-apolipoprotein B antibody, respectively; and two immunonephelo-metric assays [INA] based on a N antiserum to Lp(a) and on three monoclonal antibodies adsorbed on latex particles, respectively. Our measured Lp(a) values in plasma were lower than those found in serum, in particular for EDTA-treated (anti-apolipoprotein(a) ELISA: p < 0.01, anti-apolipoprotein B ELISA: p < 0.001 and Latex enhanced INA: p < 0.001) and citrated plasma (anti-apolipoprotein(a) ELISA: p < 0.05, anti-apolipoprotein B ELISA: p < 0.001 and INA: p < 0.001). Lp(a) values measured in heparinised plasma were also lower than those found in serum, but the difference was not statistically significant.

Antibody Specificity↗
PubMed1996

Modulation of osteoclast-activating factor activity of multiple myeloma bone marrow cells by different interleukin-1 inhibitors.

We have studied the effects of several interleukin-1 (IL-1) inhibitors--IL-1 receptor antagonist (IL-1ra), soluble IL-1 receptor (sIL-1R) types I and II, and neutralizing monoclonal antibody (mAb) specific for IL-1 receptor type I--on the osteoclast-activating factor (OAF) activity of recombinant IL-1beta and of culture supernatants of unfractionated bone marrow mononuclear cells from multiple myeloma (MM) patients. The latter activity sharply correlated with the IL-1 content of culture supernatants (r = 0.949; p < 0.001). IL-1ra and sIL-1R types I and II had a clear-cut modulating effect on the OAF activity of IL-1beta at saturating doses (2-10 ng/mL); their effect was evident at 2 ng/mL and was dose-dependent over a large range of concentrations. Similarly, the three reagents neutralized the OAF activities of all MM cell supernatants in a dose-dependent fashion and completely abolished them when tested at the fixed concentration of 5 nM. The bone-resorbing activity of tumor necrosis factor-alpha (TNF-alpha) or lymphotoxin (LT), tested alone or added to MM cell supernatants, was affected not at all by IL-1ra and only minimally by sIL-1R types I and II, suggesting that little or no endogenous IL-1 was produced by the rat cells in the assay under TNF-alpha or LT stimulation. Consistent with these findings, PGE2 production elicited by IL-1beta or IL-1-rich supernatants in the rat long-bone assay was abolished by each reagent. Also, mAbs to the IL-1R p80 (type I) chains could modulate the effects of IL-1--recombinant or plasma cell-derived--in the OAF assay, but their activity was markedly less pronounced when compared with the IL-1 inhibitors, since they could never completely abolish bone resorption. Taken together, these findings demonstrate that inhibition of IL-1 interaction with cognate surface receptors on bone cells effectively counteracts its biologic activity. The findings also strongly indicate that OAF activity in conditioned medium of unfractionated myeloma bone marrow cells is predominantly, if not solely, related to IL-1beta.

Animals↗
PubMed1995

Lipoprotein(a) immunoassays: comparison of a semi-quantitative latex method and two monoclonal enzyme immunoassays.

Lipoprotein(a) is considered an independent risk factor for atherosclerosis. A variety of analytical methods have been proposed for lipoprotein(a) measurement, the majority of which require dedicated instruments and are costly to perform, particularly when the aim is to screen for high lipoprotein(a) concentrations in large populations. We evaluated the sensitivity and specificity of a newly developed semi-quantitative latex method to assess its suitability for identifying subjects with high lipoprotein(a) levels. Based on clinical data, a sensitivity limit of 20 mg/dl of total lipoprotein(a) particle was selected for the latex method. Results obtained by the latex method on 204 subjects were compared with two enzyme immunoassays using two anti-apo(a) monoclonal antibodies with different specificities. In one assay, the detecting monoclonal antibody (MAb a-5) is directed against an epitope present in a variable number depending on the apo(a) size isoforms in lipoprotein(a), while the other assay the detecting monoclonal antibody (MAb a-40) is directed against an epitope present only once in lipoprotein(a) particles, irrespective of their apo(a) size. Both the latex method and the MAb a-5 assay demonstrated a 100% sensitivity, in that no false-negative results were found using the MAb a-40 assay as the gold standard. Eleven subjects (5.4%) were misclassified as false positive by MAb a-5 assay and 23 (11.3%) were misclassified by the latex method. Based on its 100% sensitivity and 89% specificity, we conclude that the lipoprotein(a) latex method is a cost-effective rapid approach for screening large populations.

Adult↗
PubMed1995

Improved blood velocity estimation using the maximum Doppler frequency.

In vessels whose diameter is smaller than the length of the range cell or measurement volume, the maximum blood velocity is often calculated from the maximum frequency of the Doppler spectrum, using the classical Doppler equation. It is shown that the accuracy of this procedure is significantly improved at large beam-to-flow angles, if a correction for transit time broadening is made. This finding is based on the demonstration that the maximum frequency of the Doppler spectrum depends only on the maximum velocity passing through the measurement volume, but in a manner which is a function both of the Doppler shift frequency as well as the transit time broadening associated with the passage of scatterers through the beam width.

Algorithms↗
PubMed1994

Urinary alpha-amylase and serum macroamylase activities in dogs with proteinuria.

Activities of urinary alpha-amylase and serum macroamylase; concentrations of serum creatinine, immunocomplexes, and urinary protein; and patterns of proteinuria were determined in 35 dogs with proteinuria. Urinary alpha-amylase activity ranged from 37 to 4,031 U/L. Macroamylasemia was detected in 77.14% of dogs and the percentage of alpha-amylase precipitated ranged from 4.68 to 61.63. Serum alpha-amylase activity after immunoglobulin precipitation ranged from 654 to 6,390 U/L in 51.42% of the dogs; the values were higher than the reference limits. Concentrations of serum creatinine and immunocomplexes were higher than reference limits for 25.71 and 60% of dogs, respectively. Urinary protein concentrations ranged from 0.1 to 8.9 g/L. All the patterns of proteinuria were represented. Linear regression indicated correlations between urinary alpha-amylase activities, serum creatinine concentrations (P < 0.01), and concentration of immunocomplexes (P < 0.05). Mann-Whitney test indicated significantly higher urinary alpha-amylase activity (P < 0.01) and percentage of alpha-amylase precipitated (P < 0.05) in dogs with renal insufficiency.

Amylases↗
PubMed1994

[High resolution computerized tomography in the study of the lung parenchyma. Possibility of a low-dose protocol].

High-resolution CT (HRCT) is a useful technique to investigate minimal diffuse lung disease. Two major limitations of HRCT are the higher radiation dose to the patient than in conventional CT of the chest and therefore the impossibility to study the lungs completely. These limitations can be partially overcome by using a low-dose protocol with mAs reduction. In our preliminary experience on 19 patients affected with various lung diseases, the low-dose protocol exhibited poorer image quality but almost equivalent anatomical detailing; the diagnostic yield was higher than that of conventional HRCT. Thus, in our experience, low-dose HRCT makes an interesting compromise in the study of lung parenchyma.

Adult↗
PubMed1993

Studies on the possible biological effects of 50 Hz electric and/or magnetic fields: evaluation of some glycolytic enzymes, glycolytic flux, energy and oxido-reductive potentials in human erythrocytes exposed in vitro to power frequency fields.

An attempt has been made to understand whether 50 Hz electric and magnetic fields (EMFs) are involved in producing bioeffects by exposing human erythrocytes in vitro. The study evaluated some key glycolytic enzymes, glucose consumption, lactate production, energy charge, 2,3-diphosphoglycerate, and reduced glutathione levels, all of which are biochemical parameters significant to erythrocyte function. Cells exposed to individual or superimposed EMFs have not shown any significant difference compared with the controls.

2,3-Diphosphoglycerate↗
PubMed1993

Transverse Doppler spectral analysis for a correct interpretation of flow sonograms.

The classic Doppler equation predicts that scatterers moving transversely to the ultrasound beam yield a zero frequency shift in the received echoes. An original theoretical approach, which has been developed in the last few years, has demonstrated that any focused beam leads to the generation of a Doppler spectrum with a nonzero bandwidth even for a transverse flow orientation. Based on this new theory, it is shown here that "transverse" Doppler spectral analysis can also be usefully applied in vivo. Experimental results obtained by observing normal and diseased carotid arteries at 90 degrees show that the information obtained with this approach is complementary to that provided by the mean frequency alone, which is given by the classic Doppler equation.

Blood Flow Velocity↗
PubMed1993

Renal involvement in feline immunodeficiency virus infection: a clinicopathological study.

Renal tissues from 15 cats naturally infected with feline immunodeficiency virus (FIV) were examined histologically, immunohistochemically and ultrastructurally. Renal function and urinary proteins were also studied. Kidney abnormalities were found in 12 cats and were characterized by mesangial widening with segmental to diffuse glomerulosclerosis and presence of IgM and C3, and scanty IgG deposits in the mesangium. Tubulointerstitial lesions were also present. In 6 cats the lesions were severe enough to cause marked increase in blood urea nitrogen and creatinine, and heavy glomerular nonselective proteinuria. These findings suggest that a renal involvement is a frequent occurrence in FIV-infected cats. As the histopathological features observed were similar to those described in HIV-infected patients, FIV-infected cats may represent a valuable model for a better understanding of HIV-associated nephropathy in humans.

AIDS-Associated Nephropathy↗
PubMed1993

Nimesulide as a downregulator of the activity of the neutrophil myeloperoxidase pathway. Focus on the histoprotective potential of the drug during inflammatory processes.

Neutrophils, recruited to tissue sites of inflammation, release a variety of oxidants and enzymes, which are responsible for tissue damage. Among the oxidants released are potent chlorinated compounds, such as hypochlorous acid and chloramines, which induce tissue cell damage and inactivate protease inhibitors, particularly alpha 1-antitrypsin, the specific inhibitor of neutrophil elastase. In studying a rational approach to the pharmacological control of neutrophil-mediated tissue injury, we investigated the activity of the anti-inflammatory drug nimesulide. This agent reduced the function of the myeloperoxidase pathway (which generates hypochlorous acid), by exerting a cell-directed inhibitory activity, as shown by measurement of superoxide anion and hydrogen peroxide production. Nimesulide also inactivated hypochlorous acid directly and protected alpha 1-antitrypsin from the neutrophil-mediated oxidation. Thus, neutrophil elastolytic activity may be attenuated by nimesulide-spared alpha 1-antitrypsin. The prevention of oxidative inactivation of alpha 1-antitrypsin by nimesulide strictly correlates with the drug's ability to suppress the extracellular availability of hypochlorous acid. Taken together, these data suggest that nimesulide may prevent tissue injury at sites of inflammation by maintaining natural host protective systems.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1993

Comparison of conventional and transverse Doppler sonograms.

When measuring flow velocity using the conventional ultrasonic Doppler effect, beam axis-to-flow angles approaching 90 degrees are avoided as the Doppler spectrum frequency shift is known to go to zero at this angle. In this paper, the conventional Doppler technique is compared with the transverse Doppler method, in which the Doppler spectrum bandwidth is used to estimate flow, allowing flow to be probed at 90 degrees. The comparison is made using a moving thread flow phantom capable of executing various velocity profiles. This technique may allow the probing of vessels that are inaccessible to conventional oblique probing, thus complementing the conventional Doppler technique.

Blood Flow Velocity↗
PubMed1993

Nimesulide, a sulfonanilide nonsteroidal anti-inflammatory drug, inhibits mediator release from human basophils and mast cells.

Nimesulide (NIM) is a sulfonanilide nonsteroidal anti-inflammatory drug (NSAID) used in the treatment of various inflammatory diseases and chemically unrelated to other acidic NSAIDs, such as acetylsalicylic acid (ASA) and indomethacin (INDO). We investigated the effects of NIM and of its in vivo metabolite, 4-hydroxy-NIM (OH-NIM), on the release of performed (histamine) and de novo synthesized mediators (sulfidopeptide leukotriene C4 [LTC4] and prostaglandin D2 [PGD2]) from human basophils and mast cells isolated from lung parenchyma (HLMC) and skin (HSMC). Histamine release from basophils challenged with rabbit anti-human IgE antibody (anti-IgE) was enhanced by preincubation with ASA or INDO (92.2 +/- 7.1% at 10(-3) M and 61.1 +/- 6.7% at 3 x 10(-6) M, respectively; P < .001). In contrast, NIM and its metabolite, OH-NIM (10(-6) to 10(-3) M), caused concentration-dependent inhibition (2.9 to approximately 60% and 3.7 to approximately 90%, respectively) of IgE-mediated histamine release from basophils. NIM and OH-NIM also inhibited histamine release from basophils induced by the Ca++ ionophore A23187 and different protein kinase C activators, such as 12-O-tetradecanoyl-phorbol-13-acetate, bryostatin 1 and bryostatin 5. NIM and OH-NIM also inhibited the IgE-mediated histamine release from HLMC (52.3 +/- 9.6% and 66.1 +/- 12.1% at 10(-3) M, respectively; P < .0001) and HSMC (67.3 +/- 3.7% and 77.7 +/- 12.0% at 10(-3) M, respectively; P < .0001) but had little or no effect on HLMC and HSMC activated by A23187. NIM (10(-6) to 10(-3) M) markedly inhibited the de novo synthesis of LTC4 from basophils, LTC4 and PGD2 from HLMC and PGD2 from HSMC. NIM and OH-NIM potentiated, whereas ASA and INDO reversed, the inhibitory effect of adenylate cyclase agonists, such as prostaglandin E1 and forskolin. In addition, NIM and OH-NIM reversed the enhancing effects of ASA and INDO on IgE-mediated histamine release from basophils.

Adolescent↗
PubMed1992

Selenium and glutathione peroxidase variations induced by polyunsaturated fatty acids oral supplementation in humans.

Serum and erythrocyte selenium, erythrocyte and platelet glutathione-peroxidase (GSH-Px) activities, and erythrocyte reduced glutathione (GSH) content were measured in 25 healthy adult individuals before and after daily supplementation with 20 ml of fish oil for 10 weeks. Serum-Se decreased from 0.83 +/- 0.01 mumol/l to 0.75 +/- 0.02 mumol/l (mean +/- S.E.M.) (P less than 0.01); erythrocyte-Se decreased from 4.39 +/- 0.17 nmol/g hemoglobin (Hb) to 2.83 +/- 0.15 nmol/g (P less than 0.001). GSH-Px activities increased both in erythrocytes (6.93 +/- 0.24 iu/g vs 8.18 +/- 0.27 iu/g Hb, P less than 0.01) and in platelets (69.2 +/- 2.8 iu/g vs 90.9 +/- 3.6 iu/g protein, P less than 0.001). The concentration of GSH in erythrocytes fell from 9.56 +/- 0.29 mumol/g Hb to 5.90 +/- 0.30 mumol/g Hb (P less than 0.001). The effects on plasma lipids were evident only for triglycerides (before 1.96 +/- 0.16 mmol/l, after 1.75 +/- 0.14 mmol/l, P less than 0.001). We hypothesise the enrichment of erythrocyte and platelet membranes with polyunsaturated fatty acids (PUFAs), following fish oil intake, can generate increased amounts of lipid peroxides and thus allosterically activate GSH-Px: with time this is harmful for the integrity of the enzyme molecule and Se release may result. We suggest that the Se status of individuals given PUFAs is assessed before and during intake; Se supplements should only be given when serum and/or erythrocyte Se are reduced.

Administration, Oral↗
PubMed1992

Behavioral effects of L-alpha-glycerylphosphorylcholine: influence on cognitive mechanisms in the rat.

The phosphorylcholine precursor, L-alpha-glycerylphosphorylcholine (alpha-GPC), was injected at the dose of 100 mg/kg/day for 20 days to aged male rats of the Sprague-Dawley strain, 24 months old, showing a deficit of learning and memory capacity. The drug was also administered to rats with amnesia induced pharmacologically with bilateral injections of kainic acid into the nucleus basalis magnocellularis (NBM). Learning and memory capacity of the animals, studied with tests of active and passive avoidance behavior, was improved after treatment with alpha-GPC in all experimental groups. These results indicate that this drug affects cognitive mechanisms in the rat through an involvement of central neurotransmission.

Animals↗
PubMed1992

Prevalence of feline immunodeficiency virus and other retroviral infections in sick cats in Italy.

Two hundred and seventy-seven sick pet cats living in Italy were tested for antibodies to feline immunodeficiency virus (FIV) and for feline leukemia virus (FeLV) antigen. Overall, 24% of the cats resulted positive for anti-FIV antibody and 18% for FeLV antigen. FIV was isolated from the peripheral mononuclear blood cells of ten out of 15 seropositive cats examined and from one out of eight saliva samples. No FIV isolations were obtained from six serum samples cultured. Feline syncytium forming virus (FeSFV) could be isolated from blood and/or saliva in ten out of 11 FIV seropositive cats examined, in six out of nine FeLV antigen positive cats, in two cats found positive for both infection markers, and in three out of 11 cats negative for both markers. Thus, the probability of isolating FeSFV was enhanced by infection with other exogenous retroviruses.

Animals↗
PubMed1991

Increased expression of C3b and C3bi receptors on human neutrophils and monocytes induced by a glycoprotein extract from Klebsiella pneumoniae (RU41740).

RU41740 is a glycoprotein extract from Klebsiella pneumoniae with immunomodulating properties under different experimental conditions. In particular the compound is able to stimulate several functions of human phagocytes in vitro and ex vivo. Using monoclonal antibodies and flow cytometry, in this work we assessed the effect of RU41740 on surface expression of receptors for C3b (CR1) and C3bi (CR3) in human phagocytic cells in vitro. The incubation of whole blood with varying RU41740 concentrations led to a dose-dependent increase in surface expression of CR1 and CR3 on both neutrophils and monocytes when compared with control samples incubated in buffer alone. The maximal drug-induced enhancement of complement receptors was: 291% +/- 13.4% for CR1 and 265% +/- 8.5% for CR3 in neutrophils; 117% +/- 4.5% for CR1 and 98% +/- 4.1% for CR3 in monocytes. These peak effects were observed using RU41740 at a final concentration of 10 micrograms/ml and were similar to those induced by optimal concentrations of the activating compound N-formyl-methionyl-leucyl-phenylalanine (10(-7)M). Polymyxin B did not modify the RU41740-induced enhancement of CR1 and CR3 expression on phagocytes, suggesting no role for endotoxin in this activity. These results define, at least in part, the mechanism of action of RU41740 on human phagocytes in vitro and could be relevant to in vivo events during RU41740 treatment.

Adjuvants, Immunologic↗