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Biomedical subjects

A Puig

Publications and source records attributed to A Puig.

At least 19 recordsLinked to original sources
PubMed1995

Simple concentration method for bacteriophages of Bacteroides fragilis in drinking water.

A membrane of inorganic material with a honeycomb pore structure was used to concentrate phages infecting Bacteroides fragilis from drinking water. Phages were removed from the membrane with 0.25 M glycine buffer pH 9.5. Phages were not inactivated by storage in this buffer neutralized to pH 7.0 for at least 9 days at 4 degrees C. The method allows recovery of around 50% in drinking water. When the turbidity of the water increased, the efficiency of the concentration decreased markedly. The efficiency of concentration was evaluated versus a presence/absence test in 317 water samples with turbidity level below the threshold of drinking water. Results obtained by concentration of 11 provided data which were significantly more informative than the presence/absence tests carried out on 100 ml. A number of additional tests carried out with both somatic and F-specific coliphages indicated that these conclusions can be extended to these groups of bacteriophages.

Bacteriophages↗
PubMed1994

Anti-chaperone behavior of BiP during the protein disulfide isomerase-catalyzed refolding of reduced denatured lysozyme.

Folding catalysts of the endoplasmic reticulum (ER), such as protein disulfide isomerase (PDI), accelerate the slow chemical steps, such as disulfide bond formation, that accompany protein folding. Molecular chaperones of the ER, notably the heavy chain-binding protein, BiP (grp78), bind and release unfolded proteins in an ATP-dependent fashion. In vitro, the fate of reduced, denatured lysozyme is dependent on whether the substrate interacts first with BiP or PDI. Depending on the ratio of PDI to substrate and order in which the components of the reaction are mixed, PDI can exhibit a foldase/chaperone activity, which increases the rate and extent of lysozyme refolding, or it can function as an anti-chaperone that promotes the formation of inactive, disulfide-linked lysozyme aggregates (Puig, A., and Gilbert, H.F. (1994) J. Biol. Chem. 269, 7764-7771). Reduced, denatured lysozyme, but not the native protein, interacts with BiP and efficiently stimulates its peptide-dependent ATPase activity. When present at substoichiometric amounts, BiP, like PDI, facilitates the formation of large, inactive lysozyme aggregates that are non-covalently associated with BiP. BiP and PDI compete for a limited number of sites in these insoluble aggregates. If BiP is present at a high molar excess, the chaperone binds unfolded lysozyme and inhibits its aggregation by maintaining it in a soluble, yet inactive, conformation, both in the presence or absence of ATP. Increasing concentrations of BiP decrease the extent, but not the initial rate, of refolding, suggesting that BiP and PDI compete for unfolded lysozyme and that the BiP-lysozyme complex is not a very good substrate for PDI either in the presence or absence of ATP. Depending on the BiP and PDI concentrations, unfolded lysozyme may either be efficiently refolded into the native conformation in a PDI-catalyzed reaction, or it may form both soluble and insoluble BiP-lysozyme complexes. In vitro, PDI- and BiP-facilitated aggregation, as well as the competition of the two proteins for substrate, reproduces many of the features of the quality control system of the ER.

Adenosine Triphosphate↗
PubMed1994

The role of the thiol/disulfide centers and peptide binding site in the chaperone and anti-chaperone activities of protein disulfide isomerase.

The complexity of protein folding is often aggravated by the low solubility of the denatured state. The inefficiency of the oxidative refolding of reduced, denatured lysozyme results from a kinetic partitioning of the unfolded protein between pathways leading to aggregation and pathways leading to the native structure. Protein disulfide isomerase (PDI), a resident foldase of the endoplasmic reticulum, catalyzes the in vitro oxidative refolding of reduced, disulfide-containing proteins, including denatured lysozyme. Depending on the concentrations of foldase and denatured substrate and the order in which they are added to initiate folding, PDI can exhibit either a chaperone activity or an anti-chaperone activity (Puig, A., and Gilbert, H. F. (1994) J. Biol. Chem 269, 7764-7771). PDI's chaperone activity leads to quantitative recovery of native lysozyme. Its anti-chaperone activity diverts substrate away from productive folding and facilitates disulfide cross-linking of lysozyme into large, inactive aggregates that specifically incorporate PDI. A mutant PDI (NmCm-PDI), in which both the N- and C-terminal active site cysteines have been changed to serines, loses all chaperone activity and behaves as an anti-chaperone at all substrate and PDI concentrations tested. The dithiol/disulfide sites of PDI are essential for the chaperone activity observed at high PDI concentrations, but they are not required for the anti-chaperone activity found at low PDI concentrations. Inactivation of PDI's peptide/protein binding site by a specific photoaffinity label (Noiva, R., Freedman, R. B., and Lennarz, W. J. (1993) J. Biol. Chem. 268, 19210-19217) inhibits the disulfide isomerase and chaperone activity, but the protein still retains its anti-chaperone activity. In a glutathione redox buffer, lysozyme-PDI aggregates are disulfide cross-linked; however, disulfide cross-linking is not required for aggregate formation or for the incorporation of PDI into the aggregates. Although both the peptide binding site and the catalytic active sites of PDI are required for chaperone and disulfide isomerase activity, neither of these sites are involved in PDI's anti-chaperone activity. PDI's anti-chaperone activity could serve as a quality control device by providing an efficient mechanism to retain misfolded proteins in the endoplasmic reticulum (Marquardt, T., and Helenius, A. (1992) J. Cell. Biol. 117, 505-513).

Animals↗
PubMed1994

Protein disulfide isomerase exhibits chaperone and anti-chaperone activity in the oxidative refolding of lysozyme.

Reduced, denatured lysozyme tends to aggregate at neutral pH, and competition between productive folding and aggregation substantially reduces the efficiency of refolding (Goldberg, M.E., Rudolph, R., and Jaenicke, R. (1991) Biochemistry 30, 2790-2797). Protein disulfide isomerase (PDI), a catalyst of oxidative protein folding, has a variety of effects on the yield of native lysozyme during the oxidative refolding of the reduced, denatured protein. Depending on the concentration of lysozyme, the concentration of PDI, and the order in which lysozyme and PDI are added to initiate folding, PDI can produce a substantial increase or a substantial decrease in the recovery of native lysozyme, when compared with the uncatalyzed reaction. In the presence of a glutathione redox buffer, denatured lysozyme (1-10 microM) partitions almost equally between productive folding leading to native lysozyme (50-63%) and non-productive fates including the formation of disulfide cross-linked aggregates. At the higher lysozyme concentrations examined (5-10 microM), substoichiometric concentrations of PDI (0.5-1 microM) exhibit "anti-chaperone" activity; PDI actively diverts most of the denatured lysozyme away from productive folding so that only 17 +/- 9% of the lysozyme is recovered as native enzyme. PDI's anti-chaperone activity results in extensive intermolecular disulfide crosslinking of lysozyme into large, inactive aggregates. On the other hand, if PDI is initially present at a large molar excess (5-10-fold) when denatured lysozyme is diluted to initiate folding, PDI demonstrates a chaperone-like activity that prevents aggregate formation and promotes correct folding. When PDI's chaperone activity is dominant, virtually all of the denatured lysozyme is correctly folded. The schizophrenic chaperone/anti-chaperone nature of PDI activity accounts for a number of observations on in vivo protein folding, including the necessity for maintaining a high concentration of PDI in the endoplasmic reticulum and the formation of disulfide cross-linked aggregates in the endoplasmic reticulum during the expression of disulfide-containing proteins (deSilva, A., Braakman, I., and Helenius, A. (1993) J. Cell. Biol. 120, 647-655).

Animals↗
PubMed1994

New alleles at microsatellite loci in CEPH families mainly arise from somatic mutations in the lymphoblastoid cell lines.

In the analysis of 40 CEPH families, under the EUROGEM project, with a total of 29 microsatellites (26 CA-repeats, a TCTA-repeat within the vWFII-3 gene, a TTA-repeat within the PLA-2 gene, and an AAAT-repeat intragenic to the NF1 gene) from human chromosomes 12, 17, and 21, we have detected 21 cases of abnormal segregation of alleles in 16 pedigrees for a total of 14 markers (48%). In 11 cases, the abnormal transmissions were of somatic origin, 10 of which (91%) occurred in the lymphoblastoid cell lines. In 9 other cases, it was not possible to determine if the origin of the new alleles was somatic or germline, and in one case hemizygosity in several family members was observed, so its origin was germline. The 20 new mutations detected in the 22,852 meioses analysed represent a mutation frequency of 8.7 x 10(-4) per locus per allele. The germline mutation rate could be as high as 3.9 x 10(-4) per locus per gamete (from 0 to 3.9 x 10(-4)), but the rate of somatic mutations detected in the study was much higher (4.8 x 10(-4) to 8.7 x 10(-4) per locus per allele). Individual mutation rates ranged from 0 to 3.8 x 10(-3). Among the markers analysed, all three that were tri- or tetranucleotide repeats showed one or two new alleles, compared to only 10 of the 26 (38%) CA-repeats showing mutations. Three CEPH families (102, 45 and 1333) each had several mutational events, and one individual (10210) had somatic mutations for two microsatellites from different chromosomes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

[Hepatitis C virus infection in patients with porphyria].

Hepatitis C virus antibodies were studied in sera coming from 39 patients with porphyria (cutanea tarda in 17, variegate in 8, intermittent acute in 4, coproporphyria in 2 and protoporphyria in 8). Nine of 17 patients with porphyria cutanea tarda had positive antibodies, but none of the patients with other types of porphyria. All subjects with porphyria cutanea tarda had histological or laboratory liver abnormalities. There was no relationship between the presence of antibodies and frequency of alcoholism, diabetes, or carbohydrate intolerance. Family background of porphyria was significantly less frequent among patients with positive hepatitis C virus antibodies. In 13 patients, a liver biopsy was performed, always showing signs of chronic hepatitis, whose magnitude was higher in those with positive antibodies. It is concluded that, as reported previously, hepatitis C virus may be an activating factor for porphyria cutanea tarda or may potentiate its accompanying liver disease.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

[Report of a new case of small cell carcinoma of the oat-cell type in the bladder and review of the literature].

We report an additional case of small cell carcinoma of the bladder with oat cell features in a 67-year-old male patient. This tumor, recently described at this site, has clinico-pathological features that make it distinct from other bladder tumors. Histologically, it closely resembles its pulmonary counterpart with positive results for epithelial markers and neuroendocrine differentiation. The latter has been confirmed by the observation of the typical neurosecretory granules at ultrastructural level. It generally presents in the elderly male patients. It is extremely aggressive and responds poorly to the commonly used treatment. The histogenesis of this rare tumor of the bladder has, as yet, not been elucidated. The different hypotheses that have been put forward are discussed.

Aged↗
PubMed1989

[Signet ring cell adenocarcinoma of the bladder].

A case of primary signet-ring cell adenocarcinoma of the urinary bladder is described. The etiopathogenesis, pathological and clinical features, prognosis and treatment of this tumor type are discussed and the literature reviewed.

Adenocarcinoma, Mucinous↗
PubMed1988

Diaper dermatitis. Value of vitamin A topically applied.

The role of vitamin A in preventing diaper dermatitis was evaluated in a double-blind, randomized, prospective study in which 114 newborns were enrolled over an 11-month period. Patients in Group A (58 infants) were treated with a cream that contained 1,000 IU/g of vitamin A, whereas patients in Group B (56 infants) were treated with a cream that had the same composition, but it did not contain vitamin A. Each participant returned once every 15 days for six follow-up visits.

Administration, Topical↗
PubMed1984

Poland-Möbius syndrome associated with dextrocardia.

A newborn male with Möbius syndrome, Poland anomaly, and dextrocardia is described. This is the second case reported of Poland-Möbius syndrome associated with dextrocardia. The patient presented with strabismus, facial diplegia, difficulty in swallowing, hypoplasia of the left pectoralis major muscle, partial absence of the upper costal cartilages, absence of the left areola, hypoplasia of the left forearm and hand, and dextrocardia without murmurs.

Abnormalities, Multiple↗