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Biomedical subjects

P Roche

Publications and source records attributed to P Roche.

At least 55 records · Page 3Linked to original sources
PubMed1998

Progress in research towards a world without leprosy. Report of a WHO meeting in Ethiopia, February 1998.

A UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases meeting to discuss the future role of biomedical research in leprosy, was held at the Armauer Hansen Research Institute in Addis Ababa, on February 27 and 28, 1998. This was attended by more than 20 scientists from 10 countries, who met to discuss progress towards a world without leprosy.

Ethiopia↗
PubMed1997

Bilateral macular holes resulting from septic embolization.

PURPOSE: To report a previously undescribed cause of bilateral macular hole formation. METHOD: Case report. RESULTS: Septic emboli were noted at the center of the macula in both eyes of a 32-year-old man with acute bacterial endocarditis. Bilateral full-thickness macular holes later developed at the site of these retinal lesions. CONCLUSION: This case represents the first report of fundus lesions in septicemia resulting in full-thickness macular hole formation.

Adult↗
PubMed1997

Human glandular kallikrein 2 (hK2) expression in prostatic intraepithelial neoplasia and adenocarcinoma: a novel prostate cancer marker.

OBJECTIVES: We describe the expression of a potentially new tumor marker, human glandular kallikrein 2 (hK2), that may be useful as an adjunct to prostate-specific antigen (PSA) in the diagnosis and monitoring of prostate cancer. METHODS: We evaluated 257 radical prostatectomy specimens removed at the Mayo Clinic with pathologic Stage 12 adenocarcinoma to compare the cytoplasmic expression of hK2, PSA, and prostatic acid phosphatase (PAP) in benign tissue, high-grade prostatic intraepithelial neoplasia (PIN), and adenocarcinoma. Two monoclonal antibodies, hK2-A523 and hK2-G586, specific for hK2 were used, as well as antibodies against PSA (PSM-773) and PAP (polyclonal). RESULTS: Intense epithelial cytoplasmic immunoreactivity was observed in every case for hK2-A523, hK2-G586, PSA, and PAP (100% of cases, respectively). The intensity and extent of hK2 expression for both antibodies were greater in cancer than high-grade PIN; furthermore, high-grade PIN was greater than benign epithelium. Cases of Gleason primary grade 4 and 5 cancer showed hK2 staining in almost every cell, whereas there was greater heterogeneity of staining in lower grades of cancer. In marked contrast to hK2, PSA and PAP immunoreactivity was most intense in benign epithelium and stained to a lesser extent in PIN and carcinoma. The number of immunoreactive cells for hK2 and PSA was not predictive of cancer recurrence. CONCLUSIONS: hK2 was expressed in every cancer, and the expression incrementally increased from benign epithelium to high-grade PIN and adenocarcinoma. PSA and PAP displayed inverse immunoreactivity compared with hK2. The expression of hK2 and PSA was not predictive of cancer recurrence in patients with Stage T2 carcinoma. Expression of hK2 indicates that this kallikrein antigen is both prostate localized and tumor associated. Tissue expression of hK2 appears to be regulated independently of PSA and PAP. Further studies are needed to determine whether tissue immunoreactivity of hK2 will prove clinically useful in the diagnosis and monitoring of prostate cancer.

Acid Phosphatase↗
PubMed1996

The common nodABC genes of Rhizobium meliloti are host-range determinants.

Symbiotic bacteria of the genus Rhizobium synthesize lipo-chitooligosaccharides, called Nod factors (NFs), which act as morphogenic signal molecules on legume hosts. The common nodABC genes, present in all Rhizobium species, are required for the synthesis of the core structure of NFs. NodC is an N-acetylglucosaminyltransferase, and NodB is a chitooligosaccharide deacetylase; NodA is involved in N-acylation of the aminosugar backbone. Specific nod genes are involved in diverse NF substitutions that confer plant specificity. We transferred to R. tropici, a broad host-range tropical symbiont, the ability to nodulate alfalfa, by introducing nod genes of R. meliloti. In addition to the specific nodL and nodFE genes, the common nodABC genes of R. meliloti were required for infection and nodulation of alfalfa. Purified NFs of the R. tropici hybrid strain, which contained chitin tetramers and were partly N-acylated with unsaturated C16 fatty acids, were able to elicit nodule formation on alfalfa. Inactivation of the R. meliloti nodABC genes suppressed the ability of the NFs to nodulate alfalfa. Studies of NFs from nodA, nodB, nodC, and nodI mutants indicate that (i) NodA of R. meliloti, in contrast to NodA of R. tropici, is able to transfer unsaturated C16 fatty acids onto the chitin backbone and (ii) NodC of R. meliloti specifies the synthesis of chitin tetramers. These results show that allelic variation of the common nodABC genes is a genetic mechanism that plays an important role in signaling variation and in the control of host range.

Acylation↗
PubMed1996

Wastewater from the manufacture of rubber vulcanization accelerators: characterization, downstream monitoring and chemical treatment.

The content of wastewater resulting from the manufacture of rubber antioxidants and accelerators by a factory situated in the Ebro basin (Spain) has been determined using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-flame ionization detection (GC-FID). The change in the pollutants was studied in the riverbed via two modules which continuously gathered pollutants on various solid supports (activated carbon and XAD-2 resins). These modules were located in Bocal Station, lying a further 100 km downstream from the factory, and from the Zaragoza water supply. Forty-six different compounds were identified at Bocal Station, the majority resulting from the production of rubber additives. Due to the immunity of different waste substances, and to the toxic nature of some, we studied their reaction when subjected to techniques of chemical oxidation using ozone.

Antioxidants↗
PubMed1996

The NodA proteins of Rhizobium meliloti and Rhizobium tropici specify the N-acylation of Nod factors by different fatty acids.

Rhizobia synthesize mono-N-acylated chitooligosaccharide signals, called Nod factors, that are required for the specific infection and nodulation of their legume hosts. The biosynthesis of Nod factors is under the control of nodulation (nod) genes, including the nodABC genes present in all rhizobial species. The N-acyl substitution can vary between species and can play a role in host specificity. In Rhizobium meliloti, an alfalfa symbiont, the acyl chain is a C16 unsaturated or a (omega-1) hydroxylated fatty acid, whereas in Rhizobium tropici, a bean symbiont, it is vaccenic acid (C18:1). We constructed R. meliloti derivatives having a non-polar deletion of nodA, and carrying a plasmid with either the R. meliloti or the R. tropici nodA gene. The strain with the R. tropici nodA gene produced Nod factors acylated by vaccenic acid, instead of the C16 unsaturated or hydroxylated fatty acids characteristic of R. meliloti Nod factors, and infected and nodulated alfalfa with a significant delay. These results show that NodA proteins of R. meliloti and R. tropici specify the N-acylation of Nod factors by different fatty acids, and that allelic variation of the common nodA gene can contribute to the determination of host range.

Acylation↗
PubMed1996

Hairy cell leukaemia and occupational exposure to benzene.

OBJECTIVES: The role of occupational exposures in hairy cell leukaemia (HCL) was investigated through a multicentre, hospital based, case-control study. This paper analyses the role of exposure to benzene in HCL. METHODS: A population of 226 male cases of HCL and 425 matched controls were included in the study. Benzene exposure was evaluated by expert review of the detailed data on occupational exposures generated by case-control interviews. RESULTS: No association was found between HCL and employment in a job exposed to benzene (odds ratio (OR) 0.9 (95% confidence interval (95% CI) 0.6-1.3)). The sample included 125 subjects, 34 cases (15%), and 91 controls (21%) who had been exposed to benzene, as individually assessed by the experts, for at least one hour a month during one of their jobs. Benzene exposure was not associated with a risk of HCL (OR 0.8 (0.5-1.2)). No trend towards an increase in OR was detected for increasing exposures, the percentage of work time involving exposure to > 1 ppm, or the duration of exposure. No findings suggested a particular risk period, when the OR associated with the time since first or last exposure, or since the end of exposure, were examined. CONCLUSIONS: In conclusion, with the low exposures prevalent in the sample, the study did not show any association between benzene exposure and HCL.

Benzene↗
PubMed1996

Treatment with growth hormone and dexamethasone in mice transgenic for human islet amyloid polypeptide causes islet amyloidosis and beta-cell dysfunction.

Islet amyloid derived from islet amyloid polypeptide (IAPP) is a well-recognized feature of type II diabetes. However, the mechanism of islet amyloidogenesis is unknown. In vitro studies suggest that amino acid residues 20-29 in human, but not mouse, IAPP confer amyloidogenicity consistent with the absence of spontaneous islet amyloidosis in mice. Several clinical and in vitro studies suggest that increased synthetic rates of IAPP predispose to IAPP-amyloidosis. In the present study, we sought to test the hypothesis that pharmacological induction of insulin resistance in a mouse transgenic (TG) for human IAPP would induce islet amyloid and beta-cell dysfunction. TG and non-transgenic (N-TG) control mice were treated with both rat growth hormone (12 micrograms/day) and dexamethasone (0.24 mg/day) (dex/GH) or received no treatment for 4 weeks, after which animals were killed to examine islet morphology. Treatment with dex/GH caused hyperglycemia (7.3 +/- 0.4 vs. 5.2 +/- 0.1 mmol/l, TG vs. N-TG, P < 0.001) associated with a decreased plasma insulin concentration (595 +/- 51 vs. 996 +/- 100 pmol/l, TG vs. N-TG, P < 0.05) in TG versus control mice. Islet amyloid was induced in treated TG mice but not in control mice. Islet amyloid was identified in both intra- and extracellular deposits, the former being associated with evidence of beta-cell degeneration. We conclude that dex/GH treatment in mice TG for human IAPP induces IAPP-derived islet amyloid, hyperglycemia, and islet dysfunction. The present model recapitulates the islet morphology and phenotype of type II diabetes.

Amyloid↗
PubMed1995

In Rhizobium meliloti, the operon associated with the nod box n5 comprises nodL, noeA and noeB, three host-range genes specifically required for the nodulation of particular Medicago species.

In Rhizobium meliloti, the genes required for nodulation of legume hosts are under the control of DNA regulatory sequences called nod boxes. In this paper, we have characterized three host-specific nodulation genes, which form a flavonoid-inducible operon down-stream of the nod box n5. The first gene of this operon is identical to the nodL gene identified by Baev and Kondorosi (1992) in R. meliloti strain AK631. The product of the second gene, NoeA, presents some homology with a methyltransferase. nodL mutants synthesize Nod factors lacking the O-acetate substituent. In contrast, in strains carrying a mutation in either noeA or noeB, no modification in Nod-factor structure or production could be detected. On particular hosts, such as Medicago littoralis, mutants of the n5 operon showed a very weak nodule-forming ability, associated with a drastic decrease in the number of infection threads, while nodulation of Medicago truncatula or Melilotus alba was not affected. Thus, nodL noeA and noeB are host-specific nodulation genes. By using a gain-of-function approach, we showed that the presence of nodL, and hence of O-acetylated Nod factors, is a major prerequisite for confering the ability to nodulate alfalfa upon the heterologous bacterium Rhizobium tropici.

Acetylation↗
PubMed1994

Human monoclonal autoantibodies specific for the bullous pemphigoid antigen 1 (BPAg 1).

Bullous pemphigoid (BP) is an acquired blistering skin disease associated with the production of IgG autoantibodies to the 230-kDa BP Ag (BPAg1). To better characterize the epitopes of BPAg1, we generated immortalized B cell lines secreting human mAbs (HumAbs) to BPAg1 from two BP patients whose sera reacted with native BPAg1 but not with a recombinant BP55 carboxyl-terminal peptide. Ab-producing B cell lines were established by EBV infection of CD40-activated PBMCs. Three independent clonal lines were obtained that secreted IgG HumAbs, including one IgG1 kappa (BP3) and two distinct IgG4 kappa (BP1 and BP2). These three HumAbs immunoprecipitated BPAg1. Blocking immunofluorescence experiments and phylogenetic studies showed that these Abs recognize different epitopes of BPAg1. This analysis with HumAbs further extends the serologic demonstration of the wide variety of epitopes recognized by BPAg1 autoantibodies which contrasts with the limited number of epitopes recognized by thyroid peroxidase monoclonal autoantibodies.

Antibodies, Monoclonal↗
PubMed1994

Immunohistopathological study of autoimmune pemphigus. Lack of strictly specific histological and indirect immunofluorescence criteria for paraneoplastic pemphigus.

Paraneoplastic pemphigus (PNP) is a form of pemphigus considered to bear characteristic immunohistopathological features (vacuolar-interface dermatitis, keratinocyte dyskeratosis and reactivity of patients' sera with transitional epithelia). The present study was undertaken in order to investigate whether these criteria are specific enough so as to allow the diagnosis of PNP in the absence of clinical data. A retrospective study of 66 biopsies of pemphigus revealed that one third of them comprised histological signs of PNP; one of the corresponding sera reacted with mouse bladder epithelium. However, no evidence of a neoplastic disease was present in any of the patients, and Western blotting further excluded the diagnosis of PNP. These results suggest that some of the features considered characteristic of PNP are not strictly specific for this variety of pemphigus; hence this diagnosis cannot be reliably established by histology or immunofluorescence but requires biochemical studies.

Acantholysis↗
PubMed1994

[Anatomic problems involved in the approach to the internal carotid artery].

The portion of the internal carotid artery (ICA) located above the line joining the tip of the mastoid and the angle of the mandible is in close relation with cranial nerves VII, IX, X, XI and XII as well as the middle ear at the beginning of its intrapetrous course. Several procedures have been described for exposure of the ICA at the base of the skull. Extension of the conventional sternocleidomastoid approach by mandibular subluxation associated with division of the posterior belly of the digastric muscle and the styloid apophysis or its attached muscles allows exposure of most of the ICA. To access the last centimeter of the ICA it is necessary ot drill through the mastoid apophysis and the vaginal apophysis of the tympanic bone. This approach preserves the middle ear and the facial nerve.

Aged↗
PubMed1993

A novel antigen of the dermal-epidermal junction defined by an anti-CD1b monoclonal antibody (NU-T2).

NU-T2 is a mouse monoclonal IgG1 antibody to the CD1b molecule, (cross-)reacting with an antigen of the dermal-epidermal junction (NU-T2 DEJ AG). Further immunohistochemical characterization of the NU-T2 DEJ AG showed it to display unique properties that differentiate it from other known antigens of the dermal-epidermal junction. Indeed, the NU-T2 DEJ AG is primate-specific and present only in epithelial basement membranes. In normal human skin it is expressed within the lowermost lamina lucida of the dermal-epidermal junction but not in the deep part of epidermal appendages nor in the deep part of epidermal appendages nor in the basement membrane of dermal vessels, smooth muscles or nerves. In diseases with intraepidermal or intradermal cleavage, NU-T2 reactivity was observed at the floor of the blister. In various skin specimens with a cleavage through the lamina lucida (NaCl--or dispase-split skin, bullous pemphigoid, junctional epidermolysis bullosa), NU-T2 immunoreactivity seemed reduced, being localized at the dermal side of the cleavage. These results suggest that the antigen recognized by NU-T2 is a novel component of the lamina lucida of the dermal-epidermal junction, that seems to be important for dermal-epidermal adhesion.

Adult↗