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Biomedical subjects

D Gil

Publications and source records attributed to D Gil.

At least 19 recordsLinked to original sources
PubMed2002

Turing patterns with pentagonal symmetry.

We explore numerically the formation of Turing patterns in a confined circular domain with small aspect ratio. Our results show that stable fivefold patterns are formed over a well defined range of disk sizes, offering a possible mechanism for inducing the fivefold symmetry observed in early development of regular echinoids. Using this pattern as a seed, more complex biological structures can be mimicked, such as the pigmentation pattern of sea urchins and the plate arrangements of the calyxes of primitive camerate crinoids.

Journal Article↗
PubMed2002

Regularity in irregular echinoids.

Using the mathematical concept of eutactic star, we prove that it is possible to define a morphospace for irregular echinoids by using a single parameter. In particular, we have found an extraordinary geometric property in the flower-like patterns of the five ambulacral petals of these animals. This property is fulfilled with great accuracy for a large collection of fossil specimens and provides new insights in the study of the viable skeletal designs of extinct and/or living organisms.

Animals↗
PubMed2001

Exploring the potential for subtype-selective muscarinic agonists in glaucoma.

Pilocarpine has been used to lower intraocular pressure (IOP) in glaucoma patients for more than 100 years. Since the identification of five muscarinic receptor subtypes, there has been an interest in separating the IOP-lowering effects from the ocular side effects of pupil constriction and lens accommodation. However, all these actions seem to be mediated by the M3 receptor. A novel muscarinic receptor agonist, AGN 199170, that has no activity on the M3 subtype was compared to pilocarpine in a monkey glaucoma model. This compound lowered IOP suggesting that muscarinic agonists targeted at muscarinic receptors other than the M3 subtype may be able to selectively lower IOP.

Animals↗
PubMed2001

Comparison of the lectin-binding pattern in different human melanoma cell lines.

Glycosylation is generally altered in tumour cells in comparison with their normal counterparts. These alterations are thought to be important because they contribute to the abnormal behaviour of cancer cells. Therefore, we have comparatively analysed the glycoproteins in cell extracts from human melanoma (primary site--WM35; metastatic sites-- WM239, WM9 and A375) cell lines using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and lectin staining. The glycoprotein pattern of the WM35 line differed from that of the other cell lines in having less proteins that reacted with Sambucus nigra, Maackia amurensis and Phaseolus vulgaris agglutinins. A glycoprotein of about 70 kDa had a significantly increased reaction with Sambucus nigra agglutinin in all the cell lines from metastatic sites. In the WM9, WM239 and A375 cell lines, additional bands (160-100 kDa) were stained with Phaseolus vulgaris agglutinin, suggesting that cells from metastatic sites contain more glycoproteins with beta1-6 branches. On the other hand, only minor changes in the reaction with Galanthus nivalis agglutinin, a mannose-specific lectin, were detected. Among the proteins showing different lectin staining, one, with an apparent molecular weight of 133 kDa, was recognized by antibodies as N-cadherin. The present results suggest that in human melanoma the expression of branched and sialylated complex type N-oligosaccharides consistently increased in cells from metastatic sites, and support the view that carbohydrates are associated with the acquisition of the metastatic potential of tumour cells.

Agglutinins↗
PubMed2001

An organizational model for a primary care program of home health care in Spain: a description of the program.

The National Institute of Health (INSALUD) in Spain has successfully used a model of home care that has two major components, each using the physician as part of the team that provides care at home. The first component is home health care that is provided to chronically ill, terminally ill and homebound patients, whereby professionals of primary care provide care for the patient at home, along with other professionals who provide specialized care as support elements. The second component is hospitalization at home, whereby care is provided to acutely ill patients or patients with a precocious medical or surgical discharge from the hospital. The professionals from the hospital provide the basis of care. and the primary health care professionals are the support elements. Both components incorporate a team of support.

Acute Disease↗
PubMed2001

Do fibrinolytic proteins of human bile derive exclusively from gall bladder?

BACKGROUND: In this study we addressed the issue of whether fibrinolytic proteins are presented in gall bladder bile only or in choledochus bile as well. MATERIAL AND METHODS: Gall bladder bile was obtained from 20 patients (Group I) undergoing laparoscopic cholecystectomy. Bile from common bile duct was aspirated after insertion Kehr drainage from 9 patients (Group II). The concentrations of t-PA, u-PA, PAI-1 and PAI-2 were measured by ELISA. RESULTS: We have shown that in cholecystectomized patients fibrinolytic proteins can be detected in bile both from gall bladder and from choledochus. Mean concentrations of t-PA, u-PA, PAI-1 were lower in Group II (5.69 ng/ml vs 15.7; 0.46 ng/ml vs 0.7; 16.82 ng/ml vs 26.16 ng/ml) or nearly equal for PAI-2 (343.53 ng/ml vs 341.02). All differences were insignificant (p > 0.05). CONCLUSIONS: Based on these results we concluded that the entire biliary tree produces the fibrinolytic proteins thus this production is not restricted to the gall bladder as it was earlier reported [1].

Bile↗
PubMed2000

Intracellular redistribution of nucleolin upon interaction with the CD3epsilon chain of the T cell receptor complex.

T cell activation through the antigen receptor (TCR) involves the cytoplasmic tails of the CD3 subunits CD3gamma, CD3delta, CD3epsilon, and CD3zeta. Whereas the biological significance of the cytoplasmic tails of these molecules is suggested, in part, by their evolutionarily conserved sequences, their interactions with signal transduction molecules are not completely understood. We used affinity chromatography columns of glutathione S-transferase fused to the CD3epsilon cytoplasmic tail to isolate proteins that specifically interact with this subunit. In this way, we identified the shuttling protein nucleolin as a specific CD3epsilon-interacting molecule. Using competition studies and affinity chromatography on peptide columns, we were able to identify a central proline-rich sequence as the nucleolin-interacting sequence in CD3epsilon. Transfection in COS cells of wild type CD3epsilon, but not of nonbinding mutants of CD3epsilon, resulted in redistribution of nucleolin from the nucleus and nucleoli to the cytoplasm. This property was transferred to a CD8 protein chimera by appending the cytoplasmic tail of CD3epsilon. We also found that nucleolin associated with the TCR complex. This association was increased upon TCR engagement, suggesting that the CD3epsilon/nucleolin interaction may have a role in T cell activation.

Amino Acid Sequence↗
PubMed2000

Rho regulates T cell receptor ITAM-induced lymphocyte spreading in an integrin-independent manner.

T cell receptor (TCR) engagement increases integrin-mediated adhesion to APC, resulting in the stabilization of the T cell : APC interaction and the close apposition of the two cell membranes. Here we show that engagement of either the TCR or CD3 chimeras with immobilized antibodies causes the rapid spreading of T cells in an integrin-independent fashion. This effect concurs with the polymerization of the actin cytoskeleton and is dependent on the integrity of the immunoreceptor tyrosine-based activation motifs of the CD3 subunits. Expression of a dominant negative mutant of RhoA, as well as the Rho-specific inhibitor C3 toxin, abolished TCR-induced spreading. In contrast, constitutively active or dominant negative forms of Rac and Cdc42 did not affect cell spreading. We conclude that signals emanating from the TCR can directly induce T cell spreading, independently of integrins, and via a Rho-dependent reorganization of the actin cytoskeleton.

Actins↗
PubMed2000

Expression of beta1-integrins and N-cadherin in bladder cancer and melanoma cell lines.

Changes in the expression of integrins and cadherins might contribute to the progression, invasion and metastasis of transitional cell cancer of the bladder and of melanomas. The expression of alpha5 (P < 0.001), alpha2 and beta1 (P < 0.05 - P < 0.001) integrin subunits in melanoma cells from noncutaneous metastatic sites (WM9, A375) were significantly increased as compared to cutaneous primary tumor (WM35) and metastatic (WM239) cell lines. These differences might be ascribed to the invasive character of melanoma cells and their metastasis to the noncutaneous locations. The significantly heterogeneous expression of beta1 integrin subunit in two malignant bladder cancer cell lines (T24 and Hu456) and nonsignificant differences in the expression of alpha2, alpha3, and alpha5 subunits between malignant and non-malignant human bladder cell lines do not allow an unanimous conclusion on the role of these intergrin subunits in the progression of transitional cancer of bladder. The adhesion molecule, expressed in all studied melanoma and bladder cell lines, that reacted with anti-Pan cadherin monoclonal antibodies was identified as N-cadherin except in the HCV29 non-malignant ureter cell line. However, neither this nor any other bladder or melanoma cell line expressed E-cadherin. The obtained results imply that the replacement of E-cadherin by N-cadherin accompanied by a simultaneous increase in expression of alpha2, alpha3 and alpha5 integrin subunits clearly indicates an increase of invasiveness of melanoma and, to a lesser extent, of transitional cell cancer of bladder. High expression of N-cadherin and alpha5 integrin subunit seems to be associated with the most invasive melanoma phenotype.

Antibodies, Monoclonal↗
PubMed1999

Male attractiveness and differential testosterone investment in zebra finch eggs.

Good-genes hypotheses of sexual selection predict that offspring fathered by preferred males should have increased viability resulting from superior genetic quality. Several studies of birds have reported findings consistent with this prediction, but maternal effects are an important confounding variable. Those studies that have attempted to control for maternal effects have only considered differential maternal investment after egg laying. However, female birds differentially deposit testosterone in the eggs, and this influences the development of the chick. This study shows that female birds deposit higher amounts of testosterone and 5alpha-dihydrotestosterone in their eggs when mated to more attractive males.

Animals↗
PubMed1999

Seasonal patterns of singing in the willow warbler: evidence against the fertility announcement hypothesis.

Males of many bird species use a variety of behaviour patterns that reduce their chances of being cuckolded. The 'fertility announcement' hypothesis (Møller 1991, American Naturalist, 138, 994-1014) proposes that song might be one such paternity guard. According to this hypothesis, paired males would announce their female's fertile status by singing. This has been interpreted as an honest signalling, evolutionarily stable strategy. Contrary to the predictions of this hypothesis, male willow warblers, Phylloscopus trochilus, sang very little when females were fertile. Intrusions by other males in the fertile period were not less common when males sang at higher rates. Mate guarding and singing are best interpreted as two conflicting behaviours during this period, the former being directed to the fertile female and the latter to attracting a second female, or an extrapair female. A survey of recent studies suggests that, in most passerine species studied, males do not sing during the fertile period of their females. The different conclusions of Møller (1991) are probably due to his use of population-wide estimates of the timing of singing behaviour and egg laying. Breeding asynchronies within populations would be responsible for the apparent matching between the peaks of singing activity and fertility. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗
PubMed1999

Elasticity of normal and cancerous human bladder cells studied by scanning force microscopy.

Scanning force microscopy was used for the determination of the elastic properties of living cells in their culture conditions. The studies were carried out on human epithelial cells. Two similar lines of normal cells (Hu609 and HCV29) and three cancerous ones (Hu456, T24, BC3726) were measured using the scanning force microscope in order to collect the force versus indentation curves. The BC3726 line originates from the HCV29 cell line which was transformed by the v-ras oncogene. To evaluate their elastic properties, Young's modulus values were determined. The present study has shown that normal cells have a Young's modulus of about one order of magnitude higher than cancerous ones. Such a change might be attributed to a difference in the organisation of cell cytoskeletons and requires further studies.

Biophysical Phenomena↗
PubMed1994

[Volvulus of the transverse colon: a rare cause of intestinal obstruction].

Volvulus of the transverse colon is rare, given its short and fixed mesentery and the normal fixation of the hepatic and splenic flexures of the colon. The case reported herein brings the total of reported cases to 72. Various predisposing factors have been identified, most notably congenital abnormalities, physiologic disturbances and mechanical obstruction; in our case these three factors were present. The possible role of colonoscopy in diagnosis and/or therapy is unclear. In our patient, colonoscopy proved to be of no use for diagnosis or treatment.

Adult↗
PubMed1991

ColE1-type vectors with fully repressible replication.

We have constructed two cloning vectors, pAM34 and pAM35, derived from pBR322, in which transcription of the replication primer RNA is under control of the lacZpo promoter/operator. These vectors contain a cloning cassette flanked by strong transcriptional terminators. They differ from each other by the presence (pAM34) or absence (pAM35) of gene lacIq. In the presence of repressor LacIq, replication is entirely dependent upon the addition of inducer. This feature allows the temporary maintenance of these plasmids, the construction of strains in which vector derivatives are stably integrated into the chromosome, and the recovery of nucleotide sequences adjacent to cloned fragments. Replication from the integrated plasmid can be adjusted to match the chromosome replication initiation rate required for cell growth in the absence of a functional origin, oriC.

Bacteriocin Plasmids↗
PubMed1988

Identification and sequence of gene dicB: translation of the division inhibitor from an in-phase internal start.

The dicA1 mutation, located in the replication termination region of Escherichia coli at 34.9 min, confers a temperature-sensitive, division defective phenotype to its hosts. Previous analysis had suggested that dicA codes for a repressor of a nearby division inhibition gene dicB. We show now that gene dicB is part of a complex operon. Five open reading frames (ORFs 1 to 5) preceeded by a promoter sensitive to dicA repression are found within a 1500 bp segment, and are organized into two clusters separated by a long untranslated region. Evidence for expression of these ORFs was obtained from in vitro or in vivo translation of plasmid-coded genes. IPTG-dependent cell filamentation was obtained when either the entire or the C-terminal part of the fourth ORF was placed under control of the lac promoter. In both cases, a 7 KD protein corresponding to translation from an in-frame ATG of ORF4 (dicB) was made. We propose that this C-terminal protein is the division inhibitor synthesized in dicA1 mutants.

Amino Acid Sequence↗
PubMed1988

Four methods for general anaesthesia in the rabbit: a comparative study.

The efficacy and safety of pentobarbitone, ketamine/xylazine, fentanyl/fluanisone/diazepam, and halothane/nitrous oxide anaesthesia were compared in 4 groups of six New Zealand White rabbits. Heart and respiratory rates, body temperature, reflexes, blood pressure and blood gases were measured. Pentobarbitone appeared to be unsuitable for anaesthesia in rabbits, as 5 of the 6 rabbits to whom it was administered, required artificial respiration or died. The combinations of ketamine/xylazine and fentanyl-fluanisone/diazepam both produced unpredictable levels of anaesthesia together with a substantial decline in arterial blood pressure and PO2. Despite a severe drop in blood pressure (up to 37.5%), anaesthesia with halothane and nitrous oxide was found to be superior to the other anaesthetic agents.

Anesthesia, General↗