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Biomedical subjects

F Polo

Publications and source records attributed to F Polo.

50 records · Page 3Linked to original sources
PubMed1988

Ribosomal protein interactions in yeast. Protein L15 forms a complex with the acidic proteins.

Protein L15 from Saccharomyces cerevisiae ribosomes has been shown to interact in solution with acidic ribosomal proteins L44, L44' and L45 by different methods. Thus, the presence of the acidic proteins changes the elution characteristics of protein L15 from CM-cellulose and DEAE-cellulose columns and from reverse-phase HPLC columns. Moreover, immunoprecipitation using anti-L15 specific monoclonal antibodies coprecipitates the acidic proteins, too. Conversely, antibodies raised against the acidic proteins immunoprecipitate protein L15. This coprecipitation seems to be specific since it does not involve other ribosomal proteins present in the sample. Similarly, plastic-adsorbed antibodies specific for one of the components in the L15--acidic-protein complex are able to retain the other component of the complex but cannot bind unrelated proteins. Moreover, protein L15 can be chemically cross-linked to the acidic proteins in solution. These results indicate that protein L15 might be equivalent to bacterial ribosomal protein L10 in forming a complex with the acidic proteins. Since, on the other hand, protein L15 has been shown to be immunologically related to bacterial protein L11 [Juan Vidales et al. (1983) Eur. J. Biochem. 136, 276-281] and to interact with the same region of the large ribosomal RNA as does protein L11 [El-Baradi et al. (1987) J. Mol. Biol. 195, 909-917], these results suggest strongly that protein L15 plays the same role in the yeast ribosome as proteins L10 and L11 do in the bacterial particles.

Chromatography, High Pressure Liquid↗
PubMed1988

Protein components of the erythromycin binding site in bacterial ribosomes.

Two derivatives of erythromycin have been prepared carrying either an aryl azide or a 4-nitroguaiacol as a photoreactive group. Both derivatives bind to the specific erythromycin ribosomal site as shown by saturation and competition studies. The derivatives were isotopically labeled either with tritium or with 125I, and radioactivity is covalently incorporated to the ribosome upon irradiation at the appropriate wavelength. The ribosomal proteins labeled were identified by either mono- and two-dimensional gel electrophoresis or high performance liquid chromatography. It has been found that protein L22 is the protein mainly, and under some conditions exclusively, labeled by the erythromycin derivatives. These results were confirmed using ribosomes from erythromycin-resistant mutants having a protein L22 with modified electrophoretical mobility. Protein L15 is also labeled in both cases, and the aromatic azide derivative labels to a lesser extent proteins L2 and L4. Competition experiments with erythromycin indicate that labeling in protein L22, and probably in L15, is specific, while the specificity of labeling in proteins L2 and L4 is questionable. These results indicate that the erythromycin derivatives label different ribosomal proteins than the spiramycin type of macrolides (Tejedor, F., and Ballesta, J.P.G. (1985) Biochemistry 24, 467) suggesting that the binding sites of both macrolide types are probably not identical.

Binding Sites↗
PubMed1988

Purification of Par j I, the major allergen of Parietaria judaica pollen.

A component of Parietaria judaica pollen extract, previously identified as the major allergen, then reported as Pj10 and hereafter denominated Par j I has been isolated by a combination of 65% ammonium sulphate salt precipitation and gel filtration and an Ultrogel AcA54 column. The purified allergen appeared essentially homogeneous on gel filtration HPLC. The mol. wt of Par j I was estimated by electrophoretic and chromatographic techniques. All results gave values in a range from 13 K to 25 K. Analysis in SDS-PAGE under reducing conditions revealed a broad band corresponding to a mol. wt of 10 K, which retained allergenicity when tested with a patients serum pool. CIE and CRIE patterns of the isolated Par j I displayed the two precipitating lines already reported as those exhibiting the highest IgE-binding ability. Par j I showed a specific allergenic activity about 10-fold higher than that of the whole extract and was demonstrated to be the major allergen of Parietaria judaica as assessed in 25 sensitive human sera.

Allergens↗
PubMedDate not supplied

Studies on the relationship between structure and IgE-binding ability of Parietaria judaica allergen I.

The main allergen of Parietaria judaica pollen, Par j I, is a glycopolypeptide with mol. wt about 10,000. It shows a considerable charge heterogeneity which is mostly due to the carbohydrate prosthetic groups, since treatment with trifluoromethanesulfonic acid yielded a deglycosylated protein with 8500 mol. wt that displayed only a few bands on IEF, in a narrow pH-region around 5.0. Deglycosylated Par j I exhibited a specific allergenic activity slightly lower than that of native Par j I; however, no allergenic determinants should be located on the sugar moiety since both native and deglycosylated Par j I inhibited up to a similar extent the binding of specific human IgE to P. judaica-coated wells in ELISA. The decrease of specific allergenic activity following deglycosylation could be ascribed to conformational changes evidenced by CD experiments. On the other hand, fluorescence spectroscopy showed that Par j I bears unidentified yellow-brown chromophores strongly linked to the polypeptide chain. These chromophores were not removed by TFMS treatment. Finally, reduction and alkylation caused the complete loss of allergenic activity, showing that disulphide bridges are essential for the IgE-binding ability of Par j I.

Alkylation↗
PubMedDate not supplied

Studies on the biochemical structure of the major cat allergen Felis domesticus I.

The major cat allergen, Fel d I, was purified to homogeneity from cat dander extract by sequential mAb affinity chromatography and HPLC size exclusion. The purity and allergenic activity of the preparation was demonstrated by different techniques such as HPLC, RAST inhibition, skin prick tests and CIE/CRIE. Fel d I showed a mol. wt of about 35,000 by HPLC gel filtration and of 18,000 by SDS-PAGE, confirming that it is a non-covalently linked dimer. However, SDS-PAGE analysis under reducing conditions as well as labelling experiments with 14C-iodoacetamide of 2-ME-reduced Fel d I showed that each mol. wt 18,000 monomer is comprised of two covalently S-S bound polypeptides with apparent mol. wt. of 4000 (alpha-chain) and 14,000 (beta-chain). Reduction and alkylation of Fel d I obliterated most of its allergenic activity, as determined by RAST inhibition and immunoblotting, suggesting that most of the IgE-binding sites are conformational. On the other hand, treatment of Fel d I by N-glycanase under reducing and non-reducing conditions indicated the presence of N-linked oligosaccharides in the beta-chain. Carbohydrate analysis data of the whole Fel d I molecule showed the presence of a relatively high carbohydrate content (approximately 20%). RAST inhibition experiments of native and deglycosilated allergen suggest that most IgE epitopes are located in the protein moiety of the molecule. However, the deglycosilated allergen showed a 2-4 fold reduction in its inhibition capacity of RAST as compared to the native allergen, suggesting that carbohydrates could have some role in keeping the active conformation of those epitopes. The N-terminal amino acid sequence of the beta-chain (20 residues) and most of the alpha-chain (40 residues) were determined. Both chain sequences showed no homology with other known protein sequences.

Allergens↗
PubMedDate not supplied

Cluster versus conventional immunotherapy in patients allergic to Dermatophagoides pteronyssinus: a controlled study of in vivo and in vitro parameters.

We designed a cluster schedule of immunotherapy for patients allergic to Dermatophagoides pteronyssinus which showed good safety and clinical efficacy. Here we compare the in vivo and in vitro changes with those of a conventional schedule in a controlled trial. Sixty-three patients were randomized as follows: 29 were treated with the cluster schedule, 15 with a conventional schedule and 19 received no immunotherapy. A standardized extract was used. Changes in in vivo parameters (skin prick test and conjunctival provocation test) and in in vitro parameters (IgE, IgG, IgG1 and IgG4 for the complete extract, Der p 1 and Der p 2) were measured before immunotherapy (T0), on reaching maintenance phase (T1), and after 6 (T2), 12 (T3) and 18 months of maintenance (T4). Cutaneous reactivity showed a significant decrease from T1 in both the cluster and conventional schedules, and conjunctival reactivity was also significantly lowered from T1 in these groups. Specific IgE decreased and specific IgG, IgG1 and IgG4 increased significantly from T1 in the cluster and conventional schedules. Neither of these parameters showed any changes in the group without immunotherapy. In conclusion, our cluster schedule induced changes in cutaneous and conjunctival reactivity and in immunological parameters that were similar to those achieved with the conventional schedule; these changes did not appear in patients who did not undergo immunotherapy.

Adolescent↗
PubMedDate not supplied

Immunotherapy with a mass unit Parietaria judaica extract: a tolerance study with evidence of immunological changes to the major allergen Par j 1.

Specific immunotherapy with Parietaria judaica pollen extract has been proven to be effective in the treatment of patients with respiratory allergy induced by this pollen. Nevertheless, there is some controversy about its tolerability. We conducted an open uncontrolled study to evaluate the tolerability of an aluminium adsorbed P. judaica pollen extract whose major allergen (Par j 1) content was known. Changes in immunological parameters to a complete P. judaica extract and to a purified Par j 1 preparation were monitored. Twenty-one patients (12 women, 9 men; mean age 30.2 years) suffering from rhinoconjunctivitis and/or asthma due to Parietaria pollen were enrolled. The maximum dose was established at 10 BU/ml (0.6 microgram Par j 1). Skin and conjunctival reactivity as well as serum levels of specific IgE, IgG, IgG1 and IgG4 were evaluated before therapy (T0), when 1 BU was given (T1), 2 weeks after the maintenance dose was reached (T2) and after the pollen season (T3). Four-hundred and fifteen doses were administered during immunotherapy. Only one systemic reaction (0.24% of doses) and two local reactions were registered. Reactions occurred during the administration of the highest concentrated vial. Before immunotherapy, purified Par j 1 accounted for 94.2% of the cutaneous response elicited by the complete extract. A statistically significant decrease in cutaneous response was detected after 8 weeks of treatment. There were no significant changes in conjunctival reactivity throughout the study. Specific IgG, IgG1 and IgG4 showed a pronounced and significant increase during the study, while specific IgE levels initially decreased and increased after the pollen season. The kinetics of specific antibodies to P. judaica complete extract and purified Par j 1 showed a parallel trend. The present study demonstrates that immunotherapy with P. judaica extract is well tolerated in patients suffering from rhinoconjunctivitis and/or asthma due to Parietaria pollen. This therapy induces specific changes in the immunological response to P. judaica and to purified Par j 1. These changes can be detected at very early stages of therapy.

Adolescent↗
PubMedDate not supplied

Importance of albumin in cross-reactivity among cat, dog and horse allergens.

Different allergenic proteins have been involved in cross-reactivity among animals. Albumins seem to be cross-sensitizing allergenic components. The aim of this study was to assess the importance of albumin as a cross-reactive allergen in patients sensitized to cat, dog and horse. One hundred and seventeen patients sensitized to cat were tested for IgE reactivity using skin prick tests and RAST assays with cat, dog and horse hair/dander extracts and their purified albumin extracts. RAST-inhibition studies were carried out to assess cross-reactivity among cat, dog and horse and among their purified albumins. It was found that 22% of patients exhibited specific IgE to cat albumin; 41% of patients sensitized to cat were also sensitized to dog and horse. Out of these patients, 21% had IgE to three albumins and 17% to two. Reciprocal inhibitions were observed among cat, dog and horse albumins and also among cat, dog and horse hair/dander extracts, using in the latter experiment sera from patients not sensitized to albumins. IgE binding to horse extract was inhibited 30% by its homologous albumin and IgE binding to cat and dog extracts in almost 15% by their respective albumins. It was concluded that albumins from these three animals share some epitopes that account for the cross-reactivity observed in around one-third of patients sensitized to cat, dog and horse. Nevertheless, more than 50% of specific IgE that cross-reacts among these three animals is directed to allergens other than albumin.

Albumins↗
PubMedDate not supplied

Factors influencing the clinical picture and the differential sensitization to house dust mites and storage mites.

Sensitization to house dust mites and storage mites has been studied in a number of papers, but several environmental factors and clinical conditions that differently affect sensitization to these mites are still controversial. The purpose of this study was to determine the influence of climatic conditions, occupation and patient age in the differential sensitization to house dust and storage mites, and also to search for possible different symptoms caused by each group of mites. Eighty patients sensitized to mites but not to other inhalant allergens were studied by case history and by skin prick test and serum IgE to Dermatophagoides pteronyssinus. Dermatophagoides farinae, Lepidoglyphus destructor and Tyrophagus putrescentiae. Home conditions, including content of the allergens Der p 1, Der f 1, Lep d 2 and Tp, were determined for all patients. Human activities, such as farming or similar occupations, and humidity are conditions for preferential sensitization to storage mites, while we found no difference between living in rural or urban areas. Mean age for the onset of sensitization was 6.7 years for house dust mites and 18.7 years for storage mites. Conjunctivitis was more frequent in patients allergic to storage mites, whereas perioral syndrome (itching of the tongue and swelling of the lips) was only seen in patients sensitized to T. putrescentiae. We concluded that climatic and damp conditions and human activity, but not urban or rural living environments, influence the differential sensitization to house dust mites and storage mites.

Adolescent↗
PubMedDate not supplied

[A case of lithiasis and stenosis of the urethra. Diagnostic and therapeutic problems].

The association of urethral stenosis and stones is not frequent. The urethral stenosis, particularly common in males, recognizes, as predisposing causes, urethritis, IPB, perineal trauma, neurogenic bladder and, last, but not the least important, endoscopic treatments or repeated catheterism. The authors report a case of a 42 year old man who underwent, for urolithiasis, several endoscopic examinations, which became urethral-stenosis with stones within four years. With responsible and critical behaviour, etiology, the diagnostic procedures and the therapy (invasive or not) of the urethral-stenosis are examined and evaluated. Diagnosis must be based on a non painful approach (clinical, bacteriological, ultrasonography, uro-dynamic studies); the invasive procedures must be limited as much is possible. Whatever treatment is used, which may always give sequences or complications, a prolonged follow-up is mandatory to have an objective evaluation of the results.

Adult↗