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Biomedical subjects

G Palumbo

Publications and source records attributed to G Palumbo.

At least 91 records · Page 5Linked to original sources
PubMed1994

Interaction systems between heterochromatin and euchromatin in Drosophila melanogaster.

The constitutive heterochromatin is still one of the major unsolved problems in genetics. In Drosophila melanogaster three genetic systems involving specific interactions between heterochromatic and euchromatic genetic elements are known: the Segregation Distortion, the crystal-Stellate and the abo-ABO systems. The genetic and molecular analysis of each system will allow the identification of all the components and the elucidation of the mechanisms underlying their interactions. The results of this analysis should provide insights into the biological significance of heterochromatin and into the evolutionary forces that result in the maintainance and stability of this enigmatic genetic material.

Animals↗
PubMed1994

Nasal neutrophilia and eosinophilia induced by challenge with platelet activating factor.

BACKGROUND: It has been demonstrated that in vitro platelet activating factor-acether (1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphorylcholine; PAF) has the capacity to attract eosinophils and neutrophils. We investigated whether the same applies when human nasal airways are stimulated with PAF. METHODS: Symptom scores and cytologic changes in nasal lavage fluids were evaluated in 10 atopic and 10 nonatopic subjects after nasal challenge with PAF, its precursor and metabolite, 1-O-hexadecyl-sn-glycero-3-phosphorylcholine (lyso-PAF), or saline solution. RESULTS: Nasal obstruction was reported by all the atopic subjects and seven of the 10 nonatopic subjects after nasal challenge with PAF; other symptoms such as rhinorrhea, itching, and sneezing were generally mild. PAF induced neutrophilia, which appeared after 30 minutes in atopic subjects and after 1 hour in nonatopic subjects, and peaked at 3 hours in both. Less neutrophilia was found 3 hours after stimulation with lyso-PAF in both groups of subjects. PAF also induced eosinophilia, which appeared after 30 minutes in atopic subjects and only after 3 hours in nonatopic subjects. An increase in eosinophil counts was observed 3 hours after lyso-PAF stimulation in atopic but not in nonatopic subjects. CONCLUSION: PAF can attract neutrophils and eosinophils into human nasal airways; however, the recruitment of inflammatory cells is more rapid in atopic than in nonatopic subjects, suggesting a different degree of responsiveness to PAF challenge in the two groups of subjects.

Adult↗
PubMed1994

Laparoscopy diagnosis of chlamydial salpingitis using a tubal cytobrush.

This is a report of our nontraumatic technique using a tubal cytobrush for epithelial tubal cell recovery during laparoscopy diagnosis of C. trachomatis salpingitis. We performed a three-way laparoscopy in 95 women and inserted a long flexible fallopian tube brush through one of the trocars. This technique showed that it is possible to reach the infection site avoiding vaginal contamination and that sufficient tubal cells can be obtained for isolation of intracellular pathogens. The technique also allowed rapid antigen detection directly on tubal cells by IFA and C. trachomatis isolation on cell culture. Tubal scraping did not cause bleeding or adhesions as later observed in a matched group of women who underwent further laparoscopy during GIFT.

Biopsy↗
PubMed1994

Treatment of hirsutism with flutamide and a low-dosage oral contraceptive in polycystic ovarian disease patients.

OBJECTIVE: To evaluate the clinical and hormonal response of the antiandrogen flutamide (Eulexin, Schering Plough, Milan, SA, Italy) associated with a low dosage oral contraceptive (OC) in a group of hirsute women who were unresponsive to OC treatment. DESIGN: Twenty-two polycystic ovarian disease (PCOD) patients with hirsutism were treated with flutamide (250 mg twice/d) in association with ethinyl-E2 (0.030 mg/d) plus desogestrel (0.150 mg/d) (Practil 21; Organon, Rome, Italy) for 21 d/mo. SETTING: Patients were recruited in the Institute of Obstetrical and Gynaecological Pathology, St. Bambino Hospital, University of Catania, Italy. Hormonal assays were performed in the Hormone Laboratories of St. Bambino Hospital, University of Catania, Catania, Italy. MAIN OUTCOME MEASURE: Every 2 months the hirsutism score was evaluated using the Ferriman-Gallwey hair density index. Mean plasma concentrations of LH, FSH, E2, total T, dihydrotestosterone (DHT), androstenedione (A), sex hormone-binding globulin, DHEAS were determined. RESULTS: After 8 months treatment with flutamide and low dosage OC, the Ferriman-Gallwey score improved in all patients, mean values decreasing from 25.4 +/- 3.96 to 14.6 +/- 1.92. Plasma levels of total T and E2 were unchanged, whereas LH, FSH, A, and DHT values decreased significantly. Sex hormone-binding globulin levels showed a marked increase. CONCLUSION: Flutamide, associated with low dosage OC, favorably influence the hirsutism in PCOD women who are unresponsive to OC treatment alone.

Adolescent↗
PubMed1994

Genetic analysis of Stellate elements of Drosophila melanogaster.

Repeated elements are remarkably important for male meiosis and spermiogenesis in Drosophila melanogaster. Pairing of the X and Y chromosomes is mediated by the ribosomal RNA genes of the Y chromosome and X chromosome heterochromatin, spermiogenesis depends on the fertility factors of the Y chromosome. Intriguingly, a peculiar genetic system of interaction between the Y-linked crystal locus and the X-linked Stellate elements seem to be also involved in male meiosis and spermiogenesis. Deletion of the crystal element of the Y, via an interaction with the Stellate elements of the X, causes meiotic abnormalities, gamete-genotype dependent failure of sperm development (meiotic drive), and deposition of protein crystals in spermatocytes. The current hypothesis is that the meiotic abnormalities observed in cry- males is due to an induced overexpression of the normally repressed Ste elements. An implication of this hypothesis is that the strength of the abnormalities would depend on the amount of the Ste copies. To test this point we have genetically and cytologically examined the relationship of Ste copy number and organization to meiotic behavior in cry- males. We found that heterochromatic as well as euchromatic Ste repeats are functional and that the abnormality in chromosome condensation and the frequency of nondisjunction are related to Ste copy number. Moreover, we found that meiosis is disrupted after synapsis and that cry-induced meiotic drive is probably not mediated by Ste.

Animals↗
PubMed1994

Assessment of the relevance of zona pellucida antibodies in follicular fluid of in-vitro fertilization (IVF) patients.

The presence of anti-zona pellucida antibodies in the follicular fluid of 11 women who underwent in-vitro fertilization (IVF) and embryo transfer was analysed. Only infertile couples with tubal or unexplained pathologies were included in our study, which was aimed at investigating the relationship between anti-zona pellucida antibodies in follicular fluid and failed fertilization. Whether or not these antibodies were present in some or all follicles in the same patient was also investigated. Out of 55 follicular fluids analysed, 36.3% were positive to the test and no fertilization was observed in oocytes from these follicles, while 63.6% were negative, and the oocyte fertilization rate associated with these was 51.4%. The presence of anti-zona pellucida antibodies was positively correlated with the degree of fertilization failure (P < 0.001 chi 2 test).

Adult↗
PubMed1994

Oxygen radicals inhibit human plasma acetylhydrolase, the enzyme that catabolizes platelet-activating factor.

Platelet-activating factor (PAF) can exert profound inflammatory effects at very low concentrations. In plasma, PAF is hydrolyzed to lyso-PAF by acetylhydrolase, an enzyme that circulates bound to LDL. Previous studies suggest that oxygen radicals may act synergistically with PAF to potentiate tissue injury. However, mechanisms underlying this interaction have not been elucidated. In this study we investigated whether oxygen radicals may inactivate PAF acetylhydrolase. PAF acetylhydrolase activity was measured in human plasma and purified LDL before and after exposure to radicals (10-20 nmol/min per ml) generated by xanthine/xanthine oxidase. Oxygen radicals induced > 50% loss of PAF acetylhydrolase activity within 60 s and almost complete inactivation by 10 min. This phenomenon was irreversible and independent of oxidative modification of LDL. Inactivation occurred without changes in the affinity constant of the enzyme (Km was 17.9 microM under control conditions and 15.1 microM after exposure to oxygen radicals). Inactivation was prevented by the scavengers superoxide dismutase or dimethylthiourea or by the iron chelator deferoxamine. Thus, superoxide-mediated, iron-catalyzed formation of hydroxyl radicals can rapidly and irreversibly inactivate PAF acetylhydrolase. Since concomitant production of PAF and oxygen radicals can occur in various forms of tissue injury, inactivation of acetylhydrolase might represent one mechanism by which oxygen radicals may potentiate and prolong the proinflammatory effects of PAF.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1994

Interleukin-6 production induced in peripheral blood mononuclear cells by a serum factor from IgA nephropathy patients is inhibited in vitro by specific sugars.

The basal production of IL-6 by cultured peripheral blood mononuclear cells (PBMC) from patients with IgAN, is markedly higher (A, 109 pg/ml) as compared to that of PBMC of either patients without clinical signs (I, 39 pg/ml) or appropriate controls (C, 44 pg/ml). When PBMC from healthy subjects were incubated in the presence of sera from patients A, the IL-6 production was strongly enhanced. No such an effect was observed by stimulating PBMC with sera from the other two groups of subjects (I, C). In another experiment we observed that the IL-6 production stimulated by serum from patients A could be inhibited by addition of specific monosaccharides. The inhibitory effect was rapidly abolished when the sugar-containing medium was substituted with the original one. Finally molecular components from serum of A were grossly separated by gel column chromatography. Individual fractions were incubated with PBMC of C: fractions with Mr > 30,000 highly stimulated the release of IL-6 (up to 1320 pg/ml); fractions with lower molecular weight were inactive. The data suggest the presence of an IL-6 releasing factor in the serum of IgAN patients. Although the chemical nature of such a factor is not yet established, the observations reported focus our attention to the lectins family. Since this factor seems potentially important in the understanding of the pathogenesis of IgAN, both its isolation and structural/functional characterization deserve further efforts.

Biological Factors↗
PubMed1994

[Protection by blockers against human low density lipoprotein peroxidation induced by oxygen free radicals].

Previous studies in other systems have shown that beta-receptor blockers may effectively inhibit oxygen radical-induced lipid peroxidation. On the other hand, it has been recently proposed that oxygen free radicals can induce peroxidation of human low density lipoproteins (LDL), and that peroxidized LDL may be an atherogenic stimulus. Chemically modified LDL are internalized by macrophages via a specific cell surface receptor that was termed the scavenger receptor. This phenomenon may induce foam cells transformation in vivo. In the present study we investigated whether beta-blockers may reduce oxygen radical-mediated LDL peroxidation. Purified human LDL were oxidized by exposure to oxygen free radicals generated by xanthine (0.2 mM) and xanthine oxidase (100 mU) at 37 degrees C after a pre-incubation (30 min) in presence of different concentrations (from 1 to 30 microM) of acebutolol, metoprolol or propranolol, three agents with a different degree of lipophilicity. Peroxidation was measured from malonyldihaldehyde (MDA) production. Data have shown a significant percent inhibition of MDA formation in presence of beta-blockers (from 33 to 85%). Thus, beta-blockers reduced peroxidation of human LDL in vitro at clinically relevant concentrations. The order of potency appears to follow the degree of lipophilicity. These data suggest that, although beta-blockers are known to adversely effect lipid metabolism, these agents might on the other hand prevent atherogenesis via a mechanism of inhibition of LDL peroxidation in vivo and reduced foam cells formation.

Acebutolol↗
PubMed1994

[The peroxidation of human glycosylated low-density lipoproteins is mediated by the superoxide radical: the protective effects of superoxide dismutase].

Low-density lipoproteins (LDL) oxidized by oxygen radicals are a potent atherogenic stimulus. Chemically modified LDL are internalized by macrophages via a specific cell surface receptor that was termed the scavenger receptor, and could induce foam cell transformation. Post-translational nonenzymatic glycosylation of low density lipoprotein (LDL) occurs in vivo in diabetic patients. Glycosylated LDL (glcLDL) is degraded by macrophages in part by the classic LDL-receptor and in part by the scavenger receptor. This latter mechanism may contribute to the formation of foam cells and acceleration of atherosclerosis in diabetes mellitus. Oxygen free radicals (ORs) could induce LDL peroxidation and subsequent formation of foam cells. Glycosylation may alter protein conformation. A free radical is any chemical species that has an unpaired electron. This property renders it highly chemically reactive. When a radical reacts with a non radical another free radical is generated. This characteristic enables radicals to trigger chain reactions. Oxygen radicals are: superoxide anion (.O2-), hydroxyl radical (.OH) and hydrogen peroxide (H2O2). Thus, the aim of this study was to investigate whether glcLDL are susceptible to peroxidative modification by ORs. GlcLDL was prepared incubating LDL with 40 mM glucose in sterile phosphate-buffer-EDTA 1 mM for 10 days at 37 degrees C. Control LDL (cLDL) was similarly incubated with buffer but without glucose. After this preparation both forms of LDL were oxidized by CuSO4 (15 microM for 20 hours at 37 degrees C) or by xanthine/xanthine oxidase (X:2 mM/XO: 100 mU for 20 hours at 37 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)

Diabetes Mellitus↗
PubMed1993

Trypsin-resistant regions of thyroglobulin: possible relationship with intermonomeric contact site(s).

Upon incubation of bovine thyroglobulin with trypsin at high enzyme/substrate ratio, some fragments with apparent masses between 18 and 31 kDa resisted prolonged digestion. Their NH2-terminal sequences were determined. All fragments overlapped with some of the Cys-rich repeats that compose a large part of thyroglobulin and are predicted to have a rigid structure. Among the inserts that interrupt the cysteine-rich repeats, for which several data indicate a location at the surface of thyroglobulin, the insert of repeat 1.7 was unique because of its resistance to proteolysis. This insert, although exposed at the surface of the protein, may be hidden in a region of contact between thyroglobulin monomers.

Amino Acid Sequence↗
PubMed1992

The origin of the electrophoretic doublet of thyroglobulin.

Bovine and human thyroglobulin show two closely migrating bands in reducing SDS-PAGE. Limited digestion with chymotrypsin, trypsin and thermolysin converted the slower band of the doublet into a peptide identical to the faster band, with an apparent mass of 270 kDa, in both species. The starting point of the faster band of the doublet was established at Ileu 520 with native bovine Tg and at Ser 503 with native human Tg, and at Ser 503 and Ser 504 with chymotrypsin-digested bovine and human Tg, respectively. These data explain the electrophoretic heterogeneity of thyroglobulin and unveil a region highly susceptible to proteolysis at about 500 residues from the NH2-terminus of the molecule.

Amino Acid Sequence↗
PubMed1992

Diaper dermatitis: a study of contributing factors.

A 44-week clinical study was carried out on a large sample of the Italian infant population to measure the incidence of diaper (napkin) dermatitis and to identify the factors related to the development of diaper dermatitis. Factors such as age, sex, the presence of atopic dermatitis, the general state of health of the child, the use of drugs and the type of diaper used were recorded. At the end of the test, 2169 clinical dermatological examinations were performed. The frequency of episodes of diaper dermatitis was 15.2%. Statistical correlations between diaper dermatitis and age, presence of atopic dermatitis, and health conditions were found.

Age Factors↗
PubMed1992

[Calcium channel blockers inhibit human low-density lipoprotein peroxidation induced by oxygen free radicals in vitro].

Previous studies have shown that calcium-antagonists may reduce the development of experimental atherosclerosis, and that nifedipine may slow progression of coronary atherosclerosis in man. The mechanisms responsible for this effect are still unclear. It has been recently proposed that oxygen-free radicals can induce peroxidation of human low-density lipoproteins (LDL), and that peroxidized LDL may be an atherogenic stimulus. Chemical modified LDL are internalized by macrophages via specific cell surface receptor that was termed the scavenger receptor, and could induce foam cells transformation in vivo. Previous studies on other systems have shown that calcium-antagonists may effectively inhibit oxygen radical-induced lipid peroxidation. These drugs, though differing widely in their chemical structure, are lipophilic to various degrees and presumably would concentrate in the lipid domain of the phospholipid-rich membranes. Therefore, the aim of the present study was to investigate whether calcium-channel blockers may reduce human LDL peroxidation. Purified human LDL were exposed to oxygen radicals generated by xanthine-xanthine oxidase (18 hours) after a pre-incubation (30 min) in presence of different concentrations of nifedipine, diltiazem and verapamil. Peroxidation was measured from malonyldialdehyde production. The results show that calcium-antagonists prevent LDL peroxidation. Thus, calcium-antagonists may reduce peroxidation of human LDL in vitro, at clinically relevant concentrations. These data suggest that reduced formation of atherogenic peroxidized LDL may be an additional mechanism for the anti-atherosclerotic effects of calcium-antagonists in vivo.

Arteriosclerosis↗
PubMed1991

Direct photoaffinity labeling of tubulin with colchicine.

Ultraviolet irradiation of the [3H]colchicine-tubulin complex leads to direct photolabeling of tubulin with low but practicable efficiency. The bulk (70% to greater than 90%) of the labeling occurs on beta-tubulin and appears early after irradiation, whereas alpha-tubulin is labeled later. The labeling ratio of beta-tubulin to alpha-tubulin (beta/alpha ratio) is reduced by prolonged incubation, prolonged irradiation, urea, high ionic strength, the use of aged tubulin, dilution of tubulin, or large concentrations of colchicine or podophyllotoxin. Glycerol increases the beta/alpha ratio. Limited data with [3H]podophyllotoxin show that it covalently bound with a similar beta/alpha distribution. Vinblastine, on the other hand, exhibits preferential attachment to alpha-tubulin. The possibilities that colchicine binds at the interface between alpha-tubulin and beta-tubulin, that the drug spans this interface, and that both subunits may contribute to the binding site are suggested.

Affinity Labels↗
PubMed1991

Analytical procedure for the determination of rufloxacin, a new pyridobenzothiazine, in human serum and urine by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the quantification of rufloxacin in human serum and urine has been developed and validated. The compounds, rufloxacin and internal standard, are extracted from buffered serum and urine using dichloromethane. They are then separated on an anion-exchange column using 0.05 M phosphate buffer-acetonitrile (80:20, v/v). The eluate is quantified by measuring the ultraviolet absorbance at 296 nm. The lower limit of detection for the analyte is 0.1 microgram/ml in serum and 0.05 micrograms/ml in urine. The method is linear from 0.3 to 10 micrograms/ml for serum and 0.1 to 10 micrograms/ml for urine. The method has been applied in a pharmacokinetic study in volunteers.

4-Quinolones↗
PubMed1991

Fibrin-dependent fibrinolytic activity during extracorporeal circulation.

Cardiopulmonary By-Pass (CPB) Surgery may at times induce a haemostatic defect, at present not too well understood, causing severe bleeding from the operative site and chest tube drain. We present here some data on antigen increase in tissue Plasminogen Activator (tPA) and D 2 Dimer (D2D) detected during CPB and apparently not compensated by enhanced Plasminogen Activator Inhibitor type 1 (PAI 1) activity. tPA concentration (antigenic) ranged around 6.15 ng/ml (SD 5.6) before thoracotomy and 5.8 g/ml (SD 4.74) 5-10 minutes after a heparin 250 IU/Kg bolus injection. During CPB, tPA increased to 20.34 ng/ml (SD 9.17) before protamine infusion, and 16.93 ng/ml (SD 8.13) after heparin neutralization. As the D2D went up to 2000-4000 ng/ml (before/after protamine) and it was not correlated by fibrinogen consumption or FDP production, we find these observations suggestive of fibrin-dependent fibrinolytic activity, as an acquired haemostatic defect developed during CPB.

Adult↗