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Biomedical subjects

R Arroyo

Publications and source records attributed to R Arroyo.

At least 19 recordsLinked to original sources
PubMed1997

Combined effect of HLA-DRB1*1501 and interleukin-1 receptor antagonist gene allele 2 in susceptibility to relapsing/remitting multiple sclerosis.

Susceptibility to multiple sclerosis (MS) is associated with HLA-DRB1*1501. Many reports have suggested associations with other loci but these results remain unconfirmed. We studied the IL-1 receptor antagonist (IL-1ra) gene polymorphism and the HLA-DR and DQ allele frequencies by DNA-based methods in both the primary chronic progressive form (PP MS) and the relapsing/remitting form (R/R MS). The frequency of DRB1*1501 and IL-1ra allele 2 were significantly higher in R/R MS. Association was more marked in the female sex and in patients with benign forms of R/R MS. On the other hand DR4 subtypes carrying a Val at position 86 in the DR beta chain were increased in PP MS. The present study indicates that MS is genetically heterogeneous and shows a combined effect of HLA-DR and IL-1ra genes in susceptibility to the R/R form of the disease.

Alleles↗
PubMed1996

Hydrolysis of used frying palm olein and sunflower oil catalyzed by porcine pancreatic lipase.

The enzymatic hydrolysis of frying used vegetable oils with different degrees of alteration were measured using porcine pancreatic lipase (acylglycerol acylhydrolase EC 3.1.1.3). Successive frying of potatoes significantly increased the level of total polar lipid content in the palm olein from 9.3 +/- 0.1 mg/100 mg oil to 26.4 +/- 0.3 mg/100 mg oil after 90 fryings, and from 4.0 +/- 0.1 mg/100 mg oil to 27.7 +/- 0.3 mg/100 mg oil in sunflower oil after 60 fryings. Triacylglycerol polymers, triacylglycerol dimers, and oxidized triacylglycerols also increased 37-, 7.9-, and 7.5-times in palm olein, respectively, and 56-, 22-, and 4.7-times in sunflower oil, respectively. However, diacylglycerols and free fatty acid levels related to hydrolytic alteration did not increase with the number of fryings in both oils. The substrate concentration in the reactor was determined by calculating the molecular weight of each oil showing a different degree of alteration. We compared the methodology used by us and that used by other authors. The results show that the methods are reproducible and that the values obtained are in concordance with theoretical values. The kinetic parameters apparent Michaelis-Menten constant (KMapp) and apparent maximum velocity of hydrolysis (Vmaxapp) were different in unused palm olein (5.1 +/- 0.7 and 166 +/- 7.6, respectively) than in sunflower oil (2.2 +/- 0.3 and 62 +/- 2.2, respectively). However, changes in KMapp and Vmaxapp were not related to the degree of alteration of the oils.

Animals↗
PubMed1996

[Paramedian thalamo-mesencephalic infarct con triphasic waves].

Triphasic waves are usually associated with metabolic encephalopathies but have been reported in patients with other etiologies. The pathophysiology of this EEG pattern remains poorly understood, although they have been attributed to lesion in the connections between the thalamus and cortex. We report a case of top-of-the-basilar artery occlusion with selective paramedian thalamic-mesencephalic infarct in which triphasic waves were evident on the EEG during clinical hypersomnia. To our knowledge this is the first reported case of triphasic waves with selective paramedian thalamomesencephalic infarct. We conclude that triphasic waves are a nonspecific manifestation of diencephalic dysfunction, probably of the paramedian thalamomesencephalic reticular system.

Aged↗
PubMed1995

New model for microsurgical training and skills maintenance.

PracticeRat (Sharpoint, Reading PA) is a system containing a simulation vein, artery and nerve, designed as an alternative to live animal use in microsurgical training. We find PracticeRat to be more expensive than living models. However, it does decrease animal usage and provides a very convenient opportunity to practice microsurgical techniques and procedures in a fairly realistic manner. Trainees can practice anytime, for any length of time, wherever microscopes are available. In this regard we find PracticeRat+ to be a useful addition to microsurgical training programs and an excellent tool for skills maintenance.

Animal Testing Alternatives↗
PubMed1995

Relationship between chemical and physical indexes and column and HPSE chromatography methods for evaluating frying oil.

Standard chemical and physical indexes, such as color index, acid value, and K270 were compared with the polar content and the specific thermoxidative and hydrolytic compounds originated during 75 potato fryings with sunflower oil. The color index, acid value, K270 and total polar content showed a significant increase (p < 0.05) after the first 30 fryings, followed by a tendency of the last three indexes to reach a near-steady state. Triglyceride polymers and triglyceride dimers showed a significant increase (p < 0.05) after 30 fryings, while the oxidized triglycerides were not increased significantly after 30 fryings. The amount of diglycerides and free fatty acids related to hydrolytic alteration did not change significantly throughout the frying operations. The significant correlations between acid value and total polar content, triglyceride dimers, triglycerides polymers and oxidized triglycerides, or between color index and polar content and triglyceride polymers or between K270 and triglyceride polymers indicate that these simple and standard methods can be applied and they are as useful as more specific methods of evaluation in the monitoring of frying operations, provided that initial values of all of these indexes are available.

Color↗
PubMed1995

Cloning and molecular characterization of two genes encoding adhesion proteins involved in Trichomonas vaginalis cytoadherence.

Cytoadherence to the vaginal epithelium is a critical step in infection by the eukaryotic flagellate Trichomonas vaginalis. Four trichomonad surface proteins (AP65, AP51, AP33 and AP23) mediate cytoadherence. The cDNA encoding the AP65 adhesin was isolated from a phagemid cDNA expression library by screening with antiserum and monoclonal antibody (mAb) raised against the purified trichomonad AP65 protein. Two clones, F11.2 and F11.5, coded for immuno-crossreactive recombinant proteins that possessed functional properties equal to the T. vaginalis AP65 adhesin. Analysis of full-length sequences corresponding to the F11.2 and F11.5 cDNAs revealed that both contained 1701-base open reading frames (ORFs) that encoded proteins of 63 281 daltons and 83 087 daltons, respectively. Comparison of the full-length sequences showed 87% identity at the nucleotide level and 91% identity at the protein level. Restriction-enzyme mapping and Southern analysis reaffirmed the distinctness of the F11.2 and F11.5 cDNAs, indicating that two different AP65 genes (now called ap65-1 and ap65-2) are present in the T. vaginalis genome in at least two copies each. Northern analysis detected high levels of transcript of approximately 1.8 kb for both ap65-1 and ap65-2 genes in trichomonads grown only in high-iron medium, confirming the transcriptional regulation of adhesin synthesis by iron. Homology searches revealed significant similarity (38% amino acid identity and 54% nucleotide identity) to malic enzymes. However, purified malic enzyme and mAb to AP65 crossreactive with malic enzyme neither inhibited cytoadherence of T. vaginalis to host cells nor prevented binding of the trichomonad AP65 to HeLa cells in a ligand assay.

Amino Acid Sequence↗
PubMed1995

Frequency of CYP2D6 allelic variants in multiple sclerosis.

Recent reports have shown association between CYP2D6 polymorphism and neuronal degenerative diseases such as Parkinson's disease. We investigated the association between this polymorphism and the risk for developing multiple sclerosis (MS). Leucocyte DNA from 118 MS patients and a control group of 200 unrelated healthy individuals was studied for the occurrence of 8 different CYP2D6 allelic variants by using allele-specific PCR amplification, XbaI and EcoRI RFLP analyses. The frequencies for these allelic variants in the MS and control groups were, respectively: CYP2D6wt 75.0% and 79.3%, CYP2D6A 0.4% and 1.3%, CYP2D6B 11.4% and 12.0%, CYP2D6C 4.2% and 2.0%, CYP2D6D 3.0% and 2.3%, CYP2D6L 0.8% and 0.3%, CYP2D6L2 5.1% and 3.0%. The frequencies of subjects with high CYP2D6 activity (those carrying two or more functional genes) were 77.1% and 73.5% in MS and control groups. The frequencies of subjects with absent CYP2D6 activity (those lacking functional genes) were 3.4% and 4.5% in MS and control groups, respectively. These results indicate that mutations at the CYP2D6 gene do not seem to be a factor in determining susceptibility to MS.

Alleles↗
PubMed1995

Characterization of cDNAs encoding adhesin proteins involved in trichomonas vaginalis cytoadherence.

Trichomonas vaginalis cytoadherence is mediated by four adhesins (AP65, AP51, AP33 and AP23). Adhesin gene expression was previously shown to be up-regulated by iron. Therefore, a cDNA library was constructed from mRNA of T. vaginalis grown in a high-iron medium. Ten cDNA clones (three for AP65, one for AP51, and six for AP33) were recognized with polyclonal antiserum or monoclonal antibody raised against these adhesins. No cross-hybridization among cDNAs of the three adhesins was observed in Southern analysis, confirming restriction mapping analysis of representative cDNAs. Southern analysis probed with representative cDNAs of the adhesins indicated multiple copies for each of the three adhesin genes. Northern analysis showed transcripts of 1.8 kilobases (kb), 1.4 kb, and 0.9 kb for AP65, AP51 and AP33, respectively. Consistent with adhesin expression, mRNAs for these adhesins were detected only when parasites were grown in high-iron conditions. Specific antibodies eluted from E. coli expressing recombinant proteins reacted only with the respective parasite adhesins. Recombinant proteins bind to fixed HeLa cells and competed with radiolabeled trichomonad adhesins for binding. Although proteinase activity is required for cytoadherence, recombinant proteins show no detectable proteinase activity. These data show that recombinant proteins from these clones exhibited characteristics of the trichomonad adhesins.

Animals↗
PubMed1995

Two Trichomonas vaginalis surface proteinases bind to host epithelial cells and are related to levels of cytoadherence and cytotoxicity.

Recent reports strongly suggest that cytoadherence and cytotoxicity by Trichomonas vaginalis require cysteine proteinase activity. Because of the large number of cysteine proteinases synthesized by T. vaginalis, a ligand assay was used to identify specific proteinases which may selectively target host cells. Two cysteine proteinases from trichomonal extracts with relative molecular masses (Mr) of 65,000 daltons (65-kDa) and 30-kDa were found to avidly bind to HeLa cell and vaginal epithelial cell surfaces. The two proteinases were distinguished by differential inhibition with leupeptin and N-alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK). Leupeptin pretreatment of live organisms inhibited the 30-kDa proteinase, which concomitantly reduced or eliminated cytoadherence. The T. vaginalis isolates with low levels of cytoadherence also had diminished or no detectable 30-kDa proteinase activity. On the other hand, TLCK pretreatment inhibited both the 30-kDa and 65-kDa proteinases, which resulted in decreased levels of cytoadherence and totally abolished contact-dependent cytotoxicity. Furthermore, isolates capable of attachment but with little or no cytotoxicity toward HeLa cells had no detectable host cell-bound 65-kDa proteinase. Finally, antiserum generated to each proteinase reacted by indirect immunofluorescence with live organisms, suggesting a surface location for both proteinases. This strategy and use of the ligand assay may permit for the deliniation of the role of two specific T. vaginalis surface proteinases in the properties of cytoadherence and cytotoxicity.

Animals↗
PubMed1994

Small scale frying of potatoes in sunflower oil: thermooxidative alteration of the fat content in the fried product.

Sets of 500 g of potatoes were fried discontinuously 15 times in 31 of sunflower oil without addition of unused oil. The fat content of fried potatoes increased with the number of fryings. The quality of the extracted oil from the fried potatoes was evaluated by a combination of column and high performance size exclusion chromatography, and compared with their respective fryer oils. Total polar content (mg 100 mg oil-1) increased after 15 fryings from 6.2 +/- 0.35 to 18.7 +/- 0.81 in the oil in the frier and to 21.2 +/- 0.92 in the fries. Triglyceride polymers, triglyceride dimers and oxidized triglycerides (mg 100 mg oil-1) increased progressively and significantly with the number of fryings either in the fryer oil or in the extracted oil, being the content of triglyceride dimers significantly higher in the extracted oil than in the oil in the fryer. Potatoes from the 15th frying contained more total alteration-oil-products, triglyceride polymers, triglyceride dimers and oxidized triglycerides (g 100 g fresh matter-1) than potatoes from the 8th frying (all p < 0.01). This fact may be of special relevance for some people who usually eat large quantities of potatoes fried in oils with a null or low turnover of fresh oil.

Cooking↗
PubMed1994

Acetylator polymorphism in multiple sclerosis.

To elucidate whether any relationship exists between genetic polymorphic acetylation and the risk for multiple sclerosis (MS), we determined this polymorphism, using sulphamethazine, in 71 patients with definite MS and in 268 age-matched controls. Thirty-seven patients (52.1%) and 151 controls (56.3%) were classified as slow acetylators (not significant difference). No relation was found between acetylator polymorphism and age at onset of disease in MS patient's group. Our results do not support the existence of any relationship between acetylator polymorphism and the risk for MS.

Acetylation↗
PubMed1994

Proteins of Entamoeba histolytica trophozoites involved in the adhesion to target cells.

To identify the molecules involved in the adhesion of Entamoeba histolytica trophozoites to target cells we used monoclonal antibodies (MAbs) and adhesion-deficient mutants. Human red blood cells (RBCs) were also used as specific carriers to identify the ameba molecules with affinity to the target cell receptors. MAbs Adh-1 and Adh-2 inhibited adhesion of RBCs to the trophozoites and recognized a 112-kDa surface protein that was present in the wild type strain, but was absent or modified in adhesion-deficient mutants. In other experiments, live trophozoites were incubated with fixed-RBCs and after lysis of the trophozoites, proteins attached to the RBCs surface were separated by PAGE, electrotransferred to nitrocellulose membranes and detected by polyclonal antibodies. The 112 kDa protein was found attached to the RBCs. Other molecules identified as proteins involved in the target cell-parasite contact were the 210, 160, 90, 70, 50 and 24 kDa proteins. The 112, 90 and 24 kDa polypeptides were functionally altered in adhesion-deficient mutants.

Animals↗
PubMed1993

Signalling of Trichomonas vaginalis for amoeboid transformation and adhesion synthesis follows cytoadherence.

The cytoadherence of Trichomonas vaginalis, the sexually transmitted flagellated protozoan, to vaginal epithelial cells (VECs) is the key to infection. Electron microscopy revealed that in vitro-grown parasites having typical globular shape transformed rapidly after contact with VECs into thin, flat, amoeboid cells, maximizing the area of adhesion to the surface of VECs. Amoebic trichomonads formed filopodia and pseudopodia, which interdigitated at distinct sites on the plasma membrane of target cells. In contrast, the amoeboid transformation did not occur for T. vaginalis interacting with HeLa cells, the previously used in vitro host model cell. Initial parasitism of VECs by a single organism was followed by establishment of a monolayer of trichomonads on the host cell. Finally, parasites adhering to either VECs or HeLa cells were induced to synthesize greater amounts of the four previously described adhesins. Therefore, distinct signals after contact with either epithelial cell type leads to the morphological transformation and/or induction of adhesion synthesis by T. vaginalis.

Animals↗