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D Domingo

Publications and source records attributed to D Domingo.

43 records · Page 3Linked to original sources
PubMed1996

Apical and basolateral endosomes of MDCK cells are interconnected and contain a polarized sorting mechanism.

We have evaluated transcytotic routes in MDCK cells for their ability to generate a polarized surface distribution of trafficking proteins by following the intracellular sorting of transferrin receptors (TRs). We find that the selective basolateral expression of TRs is maintained in the face of extensive trafficking between the apical and basolateral surfaces. Biochemical studies of receptors loaded with tracer under conditions approaching steady state indicate that TRs internalized from the two surfaces are extensively colocalized within MDCK cells and that both populations of receptors are selectively delivered to the basolateral surface. Tailless TRs in which the cytoplasmic domain has been deleted display an unpolarized cell surface distribution and recycle in an unpolarized fashion. We show by EM that wild-type receptors internalized from each surface are colocalized within endosomal elements distributed throughout the cytoplasm. By preloading endosomal elements directly accessible from the basolateral surface with transferrin (Tf)-HRP, we show that apically internalized TRs rapidly enter the same compartment. We also show that both transcytosing (apically internalized) and recycling (basolaterally internalized) TRs are delivered to the basolateral border by a distinctive subset of exocytotic, 60-nm-diam vesicles. Together, the biochemical and morphological data show that apical and basolateral endosomes of MDCK cells are interconnected and contain a signal-dependent polarized sorting mechanism. We propose a dynamic model of polarized sorting in MDCK cells in which a single endosome-based, signal-dependent sorting step is sufficient to maintain the polarized phenotype.

Amino Acid Sequence↗
PubMed1994

Nosocomial septicemia caused by Serratia plymuthica.

We report a case of nosocomial septicemia in a 79-year-old patient caused by Serratia plymuthica with no evident focus of infection. The patient was treated with gentamicin (40 mg every 8 h) during 10 days; clinical resolution of the infection was obtained after the 10-day treatment period.

Aged↗
PubMed1993

YTRF is the conserved internalization signal of the transferrin receptor, and a second YTRF signal at position 31-34 enhances endocytosis.

By functional analysis of mutant human transferrin receptors (TR) expressed in chicken embryo fibroblasts, we previously identified a tetrapeptide sequence, Y20TRF23, within the 61-residue cytoplasmic tail as the signal for high-efficiency endocytosis (Collawn, J. F., Stangel, M., Kuhn, L. A., Esekogwu, V., Jing, S., Trowbridge, I.S., and Tainer, J.A. (1990) Cell 63, 1061-1072). It has been inferred from other studies, however, that the TR internalization signal was localized to a much larger region, residues 7 through 26 (Girones, N., Alvarez, E., Seth, A., Lin, I-M., Latour, D.A., and Davis, R.J. (1991) J. Biol. Chem. 266, 19006-19012). Additionally, Tyr20 was reported to not be conserved in the Chinese hamster cytoplasmic tail sequence (Alvarez, E., Girones, N., and Davis, R.J. (1990) Biochem. J. 267, 31-35). In the studies reported here, we examined the effect of insertion of an extra copy of a YTRF sequence at three different locations within the human TR cytoplasmic domain and show that the insertion of another YTRF signal at position 31-34 in the wild-type TR, but not the other two locations, increases the rate of endocytosis 2-fold. Furthermore, introduction of YTRF at position 31-34 in an internalization-defective mutant receptor restores endocytosis to wild-type levels, indicating that YTRF signals at either positions 20-23 or 31-34 are necessary and sufficient to promote TR internalization and function in an independent and additive manner. We also report the complete primary structure of the Chinese hamster TR deduced from its cDNA sequence and show that the Tyr20 as well as the complete YTRF motif is conserved.

Amino Acid Sequence↗
PubMedDate not supplied

Selection and properties of a mouse L-cell transformant expressing human transferrin receptor.

Transferrin receptors are expressed in large quantities on tissues with high requirements for iron such as maturing erythroid cells and placenta. In addition, they are found in abundance on proliferating cells from other normal tissues as well as on a variety of tumours. Recent genetic analysis has shown that structural genes for the transferrin receptor, probably transferrin itself and for p97, a melanoma-associated antigen that exhibits primary sequence homology with transferrin and that can bind ferric iron, each map in man to chromosome 3 (refs 9-12). On this basis it has been suggested that there may be a region on chromosome 3 containing genes involved in Fe transport and that rearrangements in this region of chromosome 3 may in some circumstances be associated with malignant transformation. Furthermore, it is unresolved whether all cell types express structurally identical transferrin receptors. To study these problems, and as an initial step towards cloning the transferrin receptor gene, we describe here the derivation of mouse L-cell transformants expressing the human transferrin receptor.

Animals↗
PubMedDate not supplied

[The Helicobacter pylori adhesion gene: relation with the origin of the isolates and associated disease].

BACKGROUND: The adhesion gene (hpaA) of Helicobacter pylori isolates from different Spanish regions was studied by PCR-RFLP in order to group the strains according to the origin of the strains and to relate it with ulcer or gastritis production. METHODS: One hundred and forty three Helicobacter pylori clinical isolates were obtained from the culture of gastric biopsies (29 from Ibiza, 39 from Madrid, 36 from Almería and 39 from Avilés). After DNA extraction, a PCR was performed to amplify a 375 pb fragment of the hpaA gene which was digested with Hinfi and SauIIIa. RESULTS: The gene was detected in all of the strains studied. After digestion with Hinfi and SauIIIa, three and four patterns called 1, 2 and 3 and A, B, C and D were obtained, respectively. Strains from Madrid and Almería showed the highest hpaA genetic variability. In the relationship with the pathology, patterns 1 and A were the most prevalent in strains obtained from patients with ulcer and with gastritis. CONCLUSIONS: The results of hpaA gene study show the genetic variability of Helicobacter pylori and slight differences according to the origin were found.

Adhesins, Bacterial↗
PubMedDate not supplied

[Evaluation of a western blot technique (Helicoblot 2.0) fpr the detection of specific Heliocobacter pylori antigens in children)].

BACKGROUND: The aim of this study was to evaluate the diagnosis usefulness of antibodies detection against different specific antigens of H. pylori (Hp) in children by a Western-blot commercially available (Helicoblot 2.0). MATERIAL AND METHODS: 96 symptomatic paediatric patients in two groups were studied. Group 1: 48 patients Hp positive by culture and/or histology (mean age, 10.19 +/- 3.40 years; 27 boys and 21 girls) and group 2: 48 patients Hp negative by both culture and histology (mean age, 9.31 +/- 3.15 years; 34 boys and 14 girls). Qualitative IgG detection against the protein antigens of 19.5 kD (urease E), 26.5 kD (urease D), 30 kD (urease H), 35 kD, 89 kD (vacuolating toxin VacA) and 116 kD (cagA protein) was determined by a Western-blot assay (Helicoblot 2.0, Genelabs, Singapore). RESULTS: A specificity of 100% was obtained when reactivity against 19.5 kD protein (urease E) was considered alone. However, the best accuracy levels were observed with 26.5 kD (urease A) and 30 kD (urease H) antigens. An accuracy of 88.5% was observed when the manufacturer's recommended criteria was used (positivity of at least 116, 89 or 35 kD single bands or positivity of at least 2 bands of the 30, 26.5 or 19.5 kD). CONCLUSIONS: Helicoblot 2.0 is a good method to diagnosis Hp infection in children. A criteria combining IgG against 2 urease antigens (preferentially urease A) or one urease antigen and a virulence associated protein (CagA o VacA) is recommended.

Adult↗