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Biomedical subjects

J Rodriguez

Publications and source records attributed to J Rodriguez.

At least 73 records · Page 4Linked to original sources
PubMed1998

Iron-binding catechols oxidating lignin and chlorolignin.

Iron-chelating low-molecular-weight compounds or catecholate siderophores have been suggested to be involved in wood biodegradation. To help in understanding the mechanism involved in the enzyme-like activity of catecholate siderophores, the oxidative properties of 2,3-dihydroxybenzoic acid (DHBA) and 3, 4-dihydroxyphenylacetic acid (DHPAA) chelated with iron were studied. The pH and catechol/Fe(III) ratios were optimized for o-dianisidine oxidation, obtaining a maximum at pH 7.0, in the absence of buffer, and a catechol/Fe(III) ratio of 1:2 to DHBA and 1:1 to DHPAA was found. Under these conditions, the catechols were able to reduce Fe(III) to Fe(II) acting like siderophore models. The Fe(III) complex of DHBA and of DHPAA degraded dioxane-lignin in 60% after 2 h and 85% after 24 h, respectively. DHBA/Fe(III) oxidized the bleaching effluent (E1) in 80% in 5 min under the studied conditions.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1998

Hydroxamate iron complex with phenoloxidase activity acting on lignin and chlorolignins.

The properties of a siderophore model, acetohydroxamic acid (AHA), of desferral were studied. The pH, ionic strength, and AHA/Fe(III) ratios for o-dianisidine oxidation were optimized. Phenoloxidase activity of hydroxamates/Fe(III) acting on o-dianisidine at pH 7.0 and pH 3.0 was observed. Under these conditions, AHA was able to reduce Fe(III) to Fe(II) followed by ferrozine complexation. AHA/Fe(III) complex degraded lignin and chlorolignins from kraft effluent E1 65% and 85%, respectively, after 24 h.

Biodegradation, Environmental↗
PubMed1998

Mucoepidermoid carcinoma ex pleomorphic adenoma: nonspecific preoperative cytologic findings in six cases.

BACKGROUND: In contrast to most major salivary gland malignancies, mucoepidermoid carcinoma has been rarely documented and tentatively accepted as carcinoma ex pleomorphic adenoma. The authors present the cytologic and clinical findings for six examples of these rare tumors. METHODS: The six examples were identified during an extensive review of the authors' salivary gland files, and all were high grade mucoepidermoid carcinomas on histologic evaluation. RESULTS: Overall, mucoepidermoid carcinomas cytologically presented as non-specific high grade malignancies and consisted of highly malignant cells, in clusters or isolated, that were rarely associated with intracellular and extracellular mucin. In only two cases, a background of cellular and stromal elements consistent with pleomorphic adenoma was identified. CONCLUSIONS: Although it is nearly impossible cytologically to distinguish these lesions from other high grade primary or metastatic carcinomas (such as poorly differentiated squamous cell carcinomas, adenosquamous carcinomas, and salivary duct carcinomas), this limitation is not dramatic, as a cytologic diagnosis of high grade malignancy per se allows for proper preoperative patient management.

Adenoma, Pleomorphic↗
PubMed1998

The corticostriatal system mediates the "paradoxical" contraversive rotation but not the striatal hyperexpression of Fos induced by amphetamine early after 6-hydroxydopamine lesion of the nigrostriatal pathway.

In rats with unilateral 6-hydroxydopamine (6-OHDA) lesion of the nigrostriatal pathway, amphetamine produces ipsiversive rotational behavior and activation of Fos in the intact striatum, but practically no activation of Fos in the denervated striatum. However, a seemingly paradoxical contraversive rotation, accompanied by intense striatal Fos activation in the lesioned striatum, has been observed during the first few days postlesion. In the present work, behavioral tests and immunohistochemistry for Fos protein and tyrosine hydroxylase (TH) were combined to study striatal changes 36 h after 6-OHDA lesion and particularly the possible involvement of glutamatergic corticostriatal afferents. Injection of amphetamine (0.5 mg/kg or 5 mg/kg) induced contraversive rotation and strong and evenly distributed Fos expression in the lesioned striatum; in the contralateral striatum, however, Fos density was lower than in nonlesioned rats. Pretreatment with the N-methyl-D-aspartate (NMDA) glutamate receptor antagonist MK-801 (either 0.5 mg/kg or 5 mg/kg) did not significantly affect the hyperexpression of Fos in the lesioned striatum, but suppressed the contraversive rotation. Similarly, rats that were subjected to corticostriatal deafferentation (confirmed by sensory neglect tests) and 6-OHDA lesion (1 week or 3 weeks later) showed no significant reduction in the striatal Fos hyperexpression induced by amphetamine (0.5 mg/kg or 5 mg/kg) and no significant rotational asymmetry. In conclusion, the present results indicate that glutamatergic corticostriatal afferents are essential for the contraversive rotational behavior but not the striatal hyperexpression of Fos observed in response to amphetamine early after 6-OHDA lesion, and suggest that intense dopaminergic stimulation of striatal neurons is sufficient for induction of Fos, but that concurrent glutamatergic stimulation is necessary for the motor response.

Afferent Pathways↗
PubMed1998

How, when, and why bile duct injury occurs. A comparison between open and laparoscopic cholecystectomy.

BACKGROUND: Bile duct injury (BDI) is a severe complication of laparoscopic cholecystectomy (LC). There is general agreement about the increase of this complication after LC vs open cholecystectomy (OC), but comparative studies are scarce. The aim of this paper has been to compare the incidence and clinical features of BDI after LC vs open procedures. MATERIALS AND METHODS: 3,051 OC, performed from June 1977 to December 1988 were retrospectively analyzed and compared with 1,630 LCs performed from June 91 to August 96, for which data were prospectively recorded. Age, sex, type of BDI, performance of intraoperative cholangiography (IOC), underlying biliary pathology, morbidity, mortality, and late morbidity were all analyzed. RESULTS: BDI incidence was higher in group II (LC) (N: 16, 0.95%) than in group I, (OC, N: 19. 0.6%). BDI incidence was also higher in the group of patients in which it was necessary to convert to an open procedure (3/109, 2.7%, p < 0.05). BDIs were more frequently diagnosed intraoperatively in group I (OC, 18/19) than in group II (LC, 12/16). In both groups, BDI was more prevalent in cases operated by staff surgeons than residents, mainly in complicated gallbladder patients, with a bile duct of less than 7-mm diameter. Morbidity, postoperative stay, mortality, and late morbidity were similar after a BDI in both types of approach. CONCLUSIONS: (1) BDI increases with LC. (2) BDI after LC carries a similar postoperative morbidity and mortality to those after OC. (3) Incidence of BDI in converted cases increases significantly and this constitutes a high-risk group.

Aged↗
PubMed1998

Occupational asthma caused by exposure to asparagus: detection of allergens by immunoblotting.

BACKGROUND: Vegetables of the Liliaceae family, such as garlic or onion, have been reported to cause occupational asthma. However, there are few data on adverse reactions to asparagus. We evaluated the role of asparagus as a cause of asthma in a patient with respiratory symptoms occurring at work (horticulture) and studied relevant allergens. METHODS: A 28-year-old man complained of rhinoconjunctivitis and asthma when harvesting asparagus at work. Eating cooked asparagus did not provoke symptoms. A positive skin test reaction was observed with raw asparagus, Alternaria alternata, and grass-pollen extracts. The methacholine test demonstrated mild bronchial hyperresponsiveness. The patient had an immediate asthmatic response after challenge with raw asparagus extract. Bronchial provocation tests with boiled asparagus, A. alternata, and control extracts were negative. Two unexposed subjects with seasonal allergic asthma did not react to the raw asparagus extract. RESULTS: The double-blind, placebo-controlled food challenge with raw asparagus was negative. Serum asparagus-specific IgE was 13.9 kU(A)/l. By SDS-PAGE immunoblot, at least six IgE-binding components, ranging from 22 to 73 kDa, were detected only in raw asparagus. CONCLUSIONS: We report a case of occupational asthma caused by asparagus inhalation, confirmed by specific bronchoprovocation. Immunoblot analysis showed that asparagus allergens are very labile and quite sensitive to heat denaturation.

Adult↗
PubMed1998

Reduced amide pseudopeptide analogues of a malaria peptide possess secondary structural elements responsible for induction of functional antibodies which react with native proteins expressed in Plasmodium falciparum erythrocyte stages.

A psi[CH2NH] isoster bond was introduced by replacing one peptide bond at a time within the 1513 malaria peptide KEKMV motif to obtain a set of five pseudopeptides. The motif belongs to a Plasmodium falciparum malarial peptide coded 1513, derived from the MSP-1 protein. This high-binding motif included in the 1513 peptide is involved in the attachment of the malarial parasite to human erythrocytes. The novel malaria 1513 psi[CH2NH] surrogates were analyzed using RP-HPLC and MALDI-TOF mass spectrometry techniques. Nuclear magnetic resonance experiments allowed definition of the five pseudopeptide analogues' secondary structural features. Such structures are present in only a very few molecules in the 1513 parent peptide. A molecular model demonstrating the solution of the three-dimensional structure of the 1 513 peptide Pse-437 analogue was constructed on the basis of 1H-NMR spectral parameters. Monoclonal antibodies were generated to the five 1513 malaria peptide pseudopeptide analogues. These antibodies not only recognize the native MSP-1 (195 kDa) and its 83 kDa and 42 kDa proteolytic processing proteins but also different SPf(66)n malaria vaccine batches containing the native sequence. In addition, the mAbs were able to modify the kinetics of Plasmodium falciparum parasites' intraerythrocytic development and their ability to invade new RBCs. The presented evidence suggests that peptide bond-modified peptides could reproduce a transient state in 1513's native sequence and represent useful candidates in the development of a second generation of effective malarial vaccines.

Amides↗
PubMed1998

Modeling of facet articulation as a nonlinear moving contact problem: sensitivity study on lumbar facet response.

A finite element (FE) based scheme for modeling facet articulation in a spinal motion segment is proposed. The algorithm presented models the facet articulation as a nonlinear progressive contact problem. This algorithm is used to perform a nonlinear FE analysis of a complete L3-L4 motion segment. The role of facets in load transmission through a motion segment and its sensitivity to facet geometric parameters (i.e., spatial orientation of the facets and the gap between the facet articular surfaces) on this load transmission are studied. Compression, flexion, extension, and torsion loads are used in this study. The effect of facetectomy on gross segment response and disk fiber strains is studied by comparing the response of FE models of motion segment with and without facets. Large facet loads are obtained when the motion segment is subjected to torsional and large extension rotations, whereas minimal facet loads are observed under compression and flexion loading. Removal of facets reduces the segment stiffness considerably in torsion and results in higher strain levels in disk fibers. The facet load transmission is sensitive to facet geometric parameters, i.e., spatial orientation and initial facet joint gap. The facet loads increase uniformly with decrease in initial gap between the facet articular surfaces under compression, extension, and torsional loads. The sensitivity to spatial orientation angles of the facet is, however, found to vary with the type of loading. This sensitivity may account for the wide variation in the facet response reported in literature.

Biomechanical Phenomena↗
PubMed1998

A leucine zipper-like domain is essential for dimerization and encapsidation of bluetongue virus nucleocapsid protein VP4.

The bluetongue virus (BTV) minor protein VP4, with molecular mass of 76 kDa, is one of the seven structural proteins and is located within the inner capsid of the virion. The protein has a putative leucine zipper near the carboxy terminus of the protein. In this study, we have investigated the functional activity of this putative leucine zipper by a number of approaches. The putative leucine zipper region (amino acids [aa] 523 to 551) was expressed initially as a fusion protein by using the pMAL vector of Escherichia coli, which expresses a maltose binding monomeric protein. The expressed fusion protein was purified by affinity chromatography, and its size was determined by gel filtration chromatography. Proteins of two sizes, 51 and 110 kDa, were recovered, one equivalent to the monomeric form and the other equivalent to the dimeric form of the fusion protein. To prove that the VP4-derived sequence was responsible for dimerization of this protein, a mutated fusion protein was created in which a VP4 leucine residue (at aa 537) within the zipper was replaced by a proline residue. Analyses of the mutated protein demonstrated that the single mutation indeed prevented dimerisation of the protein. The dimeric nature of VP4 was further confirmed by using purified full-length BTV-10 VP4 recovered from recombinant baculovirus-expressing BTV-10 VP4-infected insect cells. Using chemical cross-linking and gel filtration chromatography, we documented that the native VP4 indeed exists as a dimer in solution. Subsequently, Leu537 was replaced by either a proline or an alanine residue and the full-length mutated VP4 was expressed in the baculovirus system. By sucrose density gradient centrifugation and gel filtration chromatography, these mutant forms of VP4 were shown to lack the ability to form dimers. The biological significance of the dimeric forms of VP4 was examined by using a functional assay system, in which the encapsidation activity of VP4 into core-like particles (CLPs) was studied (H. LeBlois, T. French, P. P. C. Mertens, J. N. Burroughs, and P. Roy, Virology 189:757-761, 1992). We demonstrated conclusively that dimerization of VP4 was essential for encapsidation by CLPs.

ATP-Binding Cassette Transporters↗
PubMed1998

Health service use by African Americans and Caucasians with asthma in a managed care setting.

Managed care plan members provide a population for analysis that minimizes the financial barriers to routine medical care that have been linked to high rates of asthma-related hospitalization, emergency care, and mortality among urban African Americans. We examined patterns of asthma care among 464 African American (AA) and 1,609 Caucasian (C) asthma patients, age 15 to 45 yr, in a southeast Michigan managed care system during 1993. Compared with C, AA had fewer visits to asthma specialists (0.32 versus 0.50 visits/yr, p = 0.002), and filled fewer prescriptions for inhaled steroids (1.44 versus 1.74 Rx/yr, p = 0.038), while being more likely to visit the emergency department with asthma (0.71 versus 0.28 visits/yr, p < 0. 001), to be hospitalized with asthma (0.08 versus 0.03 admissions/yr, p = 0.002), or to have filled prescriptions for oral steroids (0.91 versus 0.59 Rx/yr, p < 0.001). AA were equally likely to have visited a primary care physician for asthma (0.95 versus 0.93 visits/yr, p = 0.81). Similar physician visit profiles and discrepancies in the use of oral steroids persisted when analyzing exclusively low socioeconomic status subgroups. These results suggest that ethnic differences in patterns of asthma-related health care persist within managed care settings and are only partially due to financial barriers.

Adult↗
PubMed1998

High-dose chemotherapy for relapsed and refractory diffuse large B-cell lymphoma: mediastinal localization predicts for a favorable outcome.

PURPOSE: This study was performed to evaluate the outcome of high-dose chemotherapy and autologous transplantation in patients with diffuse B-cell large-cell lymphoma, and, specifically, to evaluate the impact of primary mediastinal localization on the outcome of high-dose chemotherapy. PATIENTS AND METHODS: A retrospective review was performed of all patients with diffuse large B-cell lymphoma who underwent autologous marrow or peripheral-blood stem-cell transplantation at our institution between January 1 986 and December 1995. RESULTS: Ninety patients were identified, of whom 31 (34%) had a primary mediastinal B-cell large-cell lymphoma (PML). Cumulative probabilities of disease-free survival, overall survival, and disease progression are 40% (95% confidence interval [CI], 29 to 51), 42% (95% CI, 31 to 53), and 52% (95% CI, 40 to 64), respectively. By univariate analysis, low lactate dehydrogenase (LDH) level and low Ann Arbor stage at transplant were associated with improved survival and disease-free survival. There was a trend for improved disease-free survival and survival for patients with PML. Multivariate stepwise Cox regression analysis showed that LDH level, Ann Arbor stage, and primary mediastinal localization were independent favorable prognostic factors for disease-free survival and survival. LDH level and Ann Arbor stage were also predictive for the risk of disease progression. CONCLUSION: Our results indicate that patients with PML may display an increased susceptibility to high-dose chemotherapy compared with other types of B-cell large-cell lymphoma. These findings, if confirmed, may have implications for the initial management of patients with PML.

Adolescent↗
PubMed1998

Determinants of prognosis in late chronic-phase chronic myelogenous leukemia.

PURPOSE: Since interferon alfa (IFN-A) became an established treatment in chronic myelogenous leukemia (CML), more patients are referred to tertiary centers in late chronic phase (ie, > 12 months after diagnosis). Trials conducted in this phase cannot be evaluated precisely unless the features that determine prognosis in late chronic-phase CML are identified. The purpose of this study is to define the prognostic determinants of late chronic-phase CML. PATIENTS AND METHODS: From 1980 to 1997,257 consecutive CML patients referred in late chronic phase were studied. Their clinical characteristics at the time of referral and their association with survival were investigated. A staging model was designed. RESULTS: The median survival from time of referral was 43 months. Pretreatment characteristics associated with worse outcome included older age, poor performance status, splenomegaly, low albumin level, high percentage of blasts or basophils in peripheral blood (PB) or bone marrow, longer duration of chronic phase, and poor-risk group as defined by the Synthesis model. Prior exposure to IFN-A was not associated with worse outcome. By multivariate analysis, characteristics associated with shorter survival were age of 60 years or older, time from diagnosis of 3 years or greater, performance status of 1 or greater, PB basophils of 7% or greater, spleen 10 cm or greater, PB blasts 3% or greater, and albumin level less than 4 g/dL. A model that included age, duration of chronic phase, performance status, and PB basophils was generated. Patients with no, one, two, or three or greater adverse factors had median survivals of 71, 49, 26, and 19 months, respectively. CONCLUSION: A staging model for late chronic-phase CML can stratify patients in four groups with significantly different outcomes. If confirmed in independent populations, such a model could be considered in the analysis of future trials of treatment strategies in late chronic-phase CML.

Adolescent↗
PubMed1998

Treatment of chronic Chagas' disease with itraconazole and allopurinol.

Four hundred four patients with chronic Chagas' disease were treated with itraconazole (6 mg/kg of body weight/day for 120 days), allopurinol (8.5 mg/kg of body weight/day for 60 days), or with a placebo of pure starch. Patients were monitored over a period of four years by clinical examination, serology, xenodiagnosis, hemoculture, and electrocardiogram. Drug tolerance was good, with only four treatments discontinued due to side effects that subsided after suspension of treatment. Parasitologic cure was evident in 44% of the those treated with allopurinol and 53% of those treated with itraconazole, and the electrocardiographic evaluation showed normalization in 36.5% and 48.2%, respectively, of patients with chronic or recent cardiopathy.

Adolescent↗
PubMed1998

Disseminating multimedia protocols over Internet for emergency and catastrophe management.

Over the last years we have developed various computing methods to assist specialized personnel on various aspects of catastrophe and emergency management. New models can address tasks such as patient triage; stabilization, resource coordination and hospital alertness and techniques based on information technologies. In this paper we present various tools (written on Java and C+2) that we created to store, represent, and disseminate practice guidelines and protocols over the World Wide Web. Guidelines and protocols are stored using a standard database program (e.g., Microsoft Access), and represented in a flowchart format linked to multimedia information such as text, pictures, sound, video or external sources of data. Using our JAVA tool, protocols can be disseminated over the Web and viewed with any browser with JAVA compliance. We have implemented 15 emergency protocols that we developed in collaboration with specialized military personnel from the Ministry of Defense, Spain. Users can access remotely those electronic protocols comparing their procedures and methods. Our goal is to enhance agreement and consensus among remote medical centers regarding emergency and catastrophe management, establishing discussions over the network. Our tools have also a potential for training medical and paramedical personnel for emergency situations.

Clinical Protocols↗
PubMed1998

A concept model for the automatic maintenance of controlled medical vocabularies.

A controlled medical vocabulary is a fundamental requirement in a range of medical informatics applications. Large vocabularies development and maintenance is labor intensive and costly. Maintainers of medical vocabularies need appropriate tools to do their work correctly. In this paper, we describe our concept model for a controlled medical vocabulary. We present how this model can check vocabulary consistency. We propose a set of tools in a distributed environment, which permits edition, visualization and maintenance of medical terminologies.

Humans↗
PubMed1997

Transformation of primary chick embryo fibroblasts by Marek's disease virus.

Marek's disease virus (MDV) is an alphaherpesvirus, which can mediate the malignant transformation of lymphocytes to form lymphomas in chickens. In this study, we demonstrate that MDV can transform primary chick embryo fibroblasts (CEF). The cell line derived from primary CEF infected with the GA strain of MDV was called CEM(MDV). The fibroblast nature of CEM(MDV) was verified by absence of cytokeratin type II. The CEM(MDV) phenotype differed from either primary CEF or MDV-infected CEF. CEM(MDV) were extensively vacuolated, with unusual multilamellar structures in the cytoplasm, The nuclei were considerably larger than those in primary CEF and were uniformly positive for proliferating cell nuclear antigen. The cell line was subcultured for more than 10 generations; however, CEM(MDV) did not support a fully productive MDV infection, because complete nucleocapsids were not detected and infectivity assays showed that cell line produced no infectious virus. PCR analyses demonstrated that this cell line carried both polypeptide 38 (pp38) and Meq DNA, MDV-specific genes associated with transformation. In addition, examination by laser scanning confocal microscopy revealed that CEM(MDV) constitutively produced MDV MEQ protein in nuclei and pp38 as well as glycoprotein B in the cytoplasm and on the plasma membrane. Growth in soft agar assay demonstrated that CEM(MDV) formed colonies, similar to HeLa and human melanoma cells. Retroviral insertion was not detected in DNA from the CEM(MDV) line.

Animals↗