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Biomedical subjects

A Lopez

Publications and source records attributed to A Lopez.

At least 163 records · Page 9Linked to original sources
PubMed1994

Comparison of a standard and a sensitive thromboplastin in monitoring low intensity oral anticoagulant therapy.

The greater precision in prothrombin time monitoring obtained using thromboplastins with low international sensitivity index (ISI) values are believed to result in improved patient care. The authors conducted a blinded prospective study of 84 random patients on low-intensity warfarin therapy who were monitored with either a sensitive (ISI, 1.3) or standard (ISI, 1.9) thromboplastin. For the patients monitored with standard and sensitive thromboplastins, respectively, no difference was found in the degree of anticoagulation (standard thromboplastin mean INR, 2.4 vs. 2.5, P = .37; sensitive thromboplastin mean INR, 2.6 vs. 2.6, P = .74; mean daily warfarin dose, 5.1 vs. 4.7 mg, P = .28) or efficacy (warfarin dosage adjustments, 117 vs. 116; clinic visits, 362 vs. 378; percentage of therapeutic INR determinations, 47% vs. 48%). In addition, no difference was found in bleeding prevalence or severity (.22 vs. .27 events per person-year observation). The authors concluded that monitoring anticoagulant therapy in the INR range of 2-3 with a standard thromboplastin may be comparable to monitoring with a more sensitive thromboplastin with respect to efficacy, safety, and degree of anticoagulation achieved.

Administration, Oral↗
PubMed1994

BUILD: a program generator for modelling experimental biological data.

BUILD is a program generator acting at source code level. The generated code corresponds to a whole application in order to model a biological process of interest using an iterative adjustment of experimental data. The program is designed to be executed in command line mode for processing of multiple data files with an individual execution control for each file. The results are completed by modular statistical and graphical functions. This approach has been shown to reduce the time and the amount of work needed for program development, debugging and maintenance. To date, BUILD has been successfully used in mathematical analysis of phenomenological approaches, but other fields of activity, such as educational software, are also conceivable.

Algorithms↗
PubMed1994

Interleukin 4 and human immunodeficiency virus stimulate LFA-1-ICAM-1-mediated aggregation of monocytes and subsequent giant cell formation.

The effects of recombinant interleukin 4 (IL-4) on cell cluster and multinucleated giant cell (MGC) formation from human immunodeficiency virus (HIV)-infected and uninfected monocytes were examined. Human blood monocytes were isolated by centrifugal elutriation and monoclonal antibody-complement-dependent lysis of residual T cells, and infected with low passage HIV strains. Monocytes were exposed to recombinant IL-4 (1 to 20 ng/ml), continuously after inoculation with HIV. Monocyte expression of ICAM-1 but not LFA-1 was significantly enhanced by IL-4 although substrate adherence was a more potent stimulus. Monocyte cluster and MGC formation was quantified after fixation and staining with Giemsa. Clusters of HIV-infected and uninfected monocytes were consistently and significantly increased at 4 to 7 days after IL-4 stimulation. The combination of HIV and IL-4 was more stimulatory than either treatment alone. In two out of five uninfected and three out of seven HIV-infected monocyte cultures, MGC formation was also markedly increased at 10 to 14 days after stimulation. Incubation with anti-LFA-1 (anti-CD11a, anti-CD18) and anti-ICAM-1 (anti-CD54) monoclonal antibodies reduced IL-4-stimulated aggregation in HIV-infected and uninfected monocytes and subsequently reduced MGC formation. Anti-ICAM-1 was not as effective as anti-CD11a or anti-CD18 in inhibiting aggregation of HIV-infected monocytes and in these cultures anti-ICAM-2 was also inhibitory. Extracellular HIV antigen concentrations were not consistently reduced by anti-CD11a or anti-ICAM-1. Hence IL-4 markedly enhanced monocyte aggregation in both HIV-infected and uninfected monocytes, probably through enhanced LFA-1-ICAM-1 interactions in all cultures and LFA-1-ICAM-2 interactions in infected monocytes, leading subsequently to MGC formation in some cultures.

Antibodies, Monoclonal↗
PubMed1994

Lectin typing of beta-haemolytic streptococci of groups A and B.

Patterns of agglutination of 124 clinical isolates of beta-haemolytic streptococci (30 group A and 94 group B isolates) by 21 commercial lectins are reported. Cell suspensions were untreated. Nine (30%) of the group A isolates, and 23 (24%) of the group B isolates, were agglutinated by at least one of the lectins. Ten different patterns of agglutination were observed with group A and 15 with group B streptococci. No pattern, except that of non-agglutination by any lectin, was common to group A and group B isolates. In view of the growing interest in the use of lectin typing there is a need for standardisation of assay procedures to enable meaningful comparison of the results of different research groups.

Agglutination Tests↗
PubMed1994

Acute lymphoblastic leukemia (ALL): detection of minimal residual disease (MRD) at flow cytometry.

In the present study the usefulness of a method combining multiple staining direct immunofluorescence technique together with flow cytometry in order to predict relapse in ALL is analyzed in a group of 47 patients (11 T-ALL and 36 B-ALL). Results show that this method can be applied to at least two-thirds of all ALL patients being specially useful for the T-ALL cases (100% vs 56%) as this corresponding to the incidence of "aberrant" phenotypes. The detection of an increase in the percentage of bone marrow cells displaying "aberrant" phenotypes in two consecutive samples from the same patient is of great help on predicting relapse (sensitivity of 92% and specificity of 75%).

Adolescent↗
PubMed1994

Chymotrypsin and trypsin sensitivities of avian reoviruses.

Experiments were undertaken to examine the chymotrypsin sensitivity and trypsin sensitivity of 13 avian reoviruses, and to determine if there was any correlation with pathogenicity of some chicken reoviruses. A wide variation in the degree of sensitivity of avian reoviruses to chymotrypsin and trypsin was observed. Overall, the infectivity of the 13 avian reoviruses for Vero cells was markedly reduced by treatment with 0.01% chymotrypsin (the lowest concentration tested) while 0.5% trypsin significantly reduced the infectivity of 9 of 13 strains. Comparison of four avian reoviruses, three resistant and one sensitive to trypsin, for pathogenicity in day old chicks following oral inoculation showed the strains that were resistant to trypsin to be more pathogenic. Tenosynovitis and virus persistence in intestines, liver, heart and hock joint tissues occurred only in chickens inoculated with the trypsin resistant strains. It is concluded that the degree of sensitivity to chymotrypsin and trypsin among avian reoviruses is heterogenous. Sensitivity to trypsin influenced the development of tenosynovitis based on microscopic lesions and virus persistence in tissues.

Animals↗
PubMed1994

CD4 enumeration in HIV infected individuals.

In the present study, two alternative methods for the enumeration of PB CD4+ lymphocytes are compared with conventional flow cytometry (FCM): the TRAX CD4 tm enzyme immunoassay test kit and a new method using an internal biological standard (liophilized lymphocytes) for the direct enumeration of total PB CD4+ T-cells. Both methods showed an overall high degree of correlation with conventional FCM. However, the TRAxCD4 tm enzyme immunoassay showed a significant overestimation of PB CD4+ T-cells that was not only due to monocyte-derived CD4 molecules and the use of liophilized lymphocytes as an internal biological standard showed a low level of correlation for patients displaying low CD4 counts.

CD4 Lymphocyte Count↗
PubMed1993

Effects of prolactin on explant cultures of rat ventral prostate: morphological and immunohistochemical study.

Specimens derived from rat ventral prostate were cultured by an explant culture technique using differents concentrations of ovine prolactin. Sacrificed explants embedded on paraffin were sectioned for morphologic and immunocytochemical studies using antibodies against prostatic acid phosphatase, prostatic specific antigen, and wide-spectrum monoclonal keratin. Prolactin significantly stimulated the growth of these cells in the concentration range of 1 x 10(-2) ui/ml, but was inhibitory at a concentration of 1 and 0.1 ui/ml. The 1 x 10(-3) and 1 x 10(-4) ui/ml prolactin concentrations demonstrated the preservation of a glandular epithelium with a columnar shape, similar to the normal appearance of ventral prostate from rats.

Acid Phosphatase↗
PubMed1993

Structure/function analysis of the sea urchin sperm adhesive protein bindin.

The functional domain structure of bindin, an adhesive protein component of the acrosomal granule of sea urchin sperm, has been analyzed using a series of carboxyl- and amino-terminal deletion analogs of recombinant bindin expressed in Escherichia coli. Bindin, which self-associates to form macromolecular aggregates, mediates the species-specific attachment of sperm to the egg surface as well as egg-to-egg agglutination in vitro by binding to egg surface-sulfated fucose-containing glycoconjugates. Cross-species egg agglutination activity and sperm adhesion were determined for two sea urchin species, Strongylocentrotus purpuratus and S. franciscanus. We found that S. franciscanus sperm bindin agglutinates both S. franciscanus and S. purpuratus eggs whereas S. purpuratus sperm bindin displays a much more restricted specificity for homologous S. purpuratus eggs. Consistent with this result, cross-species sperm adhesion experiments demonstrate that S. franciscanus sperm also bind more efficiently to S. purpuratus eggs in comparison to S. purpuratus sperm attachment to S. franciscanus eggs. Recombinant S. purpuratus bindin demonstrates the same species-specific egg agglutination properties observed for sperm bindin. Deletion mutants of S. purpuratus bindin were tested for their ability to species specifically agglutinate eggs. We found that residues 1-74 or residues 122-236 can be deleted without a loss of the species-specific agglutination properties of bindin. Comparison of the bindin amino acid sequences from the two species reveals that all of the active deletion analogs have a central segment in common corresponding to residues 75 through 121 of S. purpuratus bindin, where the sequences are identical except for a single amino acid, Arg 77, which is an Ala residue in S. franciscanus. However, substitution of Arg 77 for Ala does not alter the species specificity of recombinant bindin, suggesting that the more divergent amino- and carboxy-terminal sequences flanking the conserved central domain determine the species specificity of bindin and either end is sufficient to impart specificity. The amino- and carboxyl-terminal thirds of S. purpuratus bindin each contain two repeats of the sequence M G G P P/V. This sequence does not occur in S. franciscanus, which instead has five repeats of the sequence M G G A/V/Q F/V/P. It is conceivable that these repeats, which vary in sequence in bindins from different species, constitute an important part of the species recognition mechanism.

Agglutination↗
PubMed1993

A survey of different high resolution visualization modes of a volumetric object with applications.

In view of the variety of 3D representation techniques, a clinical study was carried out in order to evaluate their respective usefulness. It appears that a single technique cannot be claimed to be valid for all clinical situations and that a combination of representations brings more relevant information. Among the different techniques a clear delineation must be established between those which allow the accurate definition of landmarks (multiplanar reformation, surface representation), and those which do not (integral shading, reconstructed radiology). The main point is the possibility to recognize anatomical landmarks on these latter modes and to choose oblique cut planes in relation to them. Visualization quality is strongly dependent upon the acquisition protocol which must provide a spatial resolution as isotropic as possible.

Arachnoid Cysts↗
PubMed1993

Evaluation of short research experiences in cancer.

For the past 5 years, the Cancer Education Committee of Louisiana State University Medical School (LSUMS) has selected premedical and medical students to participate in cancer research during the summer months. The students' participation is funded through a NCI R-25 training grant. Each year, LSUMS faculty from both the clinical and basic science departments provide opportunities for the students to participate in cancer research. The students also attend weekly seminars on cancer-related topics and biweekly multi-disciplinary Tumor Conferences. At the end of the summer, the students are required to submit and present a summary of their research project and to complete an evaluation form of the program. The overall evaluation of this experience has been favorable. Seventy-nine percent of the students agreed that the experience exceeded their expectations, and 83% responded that they would be willing to repeat the program. However, when asked if they planned to pursue a career in cancer research or medical oncology, 84 and 62%, respectively, were undecided. These findings raise the following questions: (1) When is the most appropriate time period in the student's education for this experience to take place? and (2) How can students' future career decisions be influenced?

Career Choice↗
PubMed1993

Interaction of lectins with Cryptosporidium parvum.

Cell surface carbohydrates from four clinical isolates of Cryptosporidium parvum were analyzed by agglutination assays using a battery of 20 highly purified lectins with affinity for receptor molecules containing N-acetyl-D-glucosamine (GlcNAc), N-acetyl-D-galactosamine, galactose, mannose, glucose, fucose, and N-acetyl-neuraminic acid. Tomentine, a lectin from the green seaweed Codium tomentosum, and UEA-II lectin, from Ulex europeus, both of them GlcNAc-specific lectins, agglutinated the oocysts. Subsequent inhibition assay confirmed the presence of this sugar on the surface of Cryptosporidium parvum oocysts. Codium fragile lectin, from another green seaweed, also exhibited agglutination activity against the oocysts. This is the first published demonstration of such an interaction between a human coccidian and lectins from seaweeds.

Animals↗
PubMed1993

C-fms protein expression by B-cells, with particular reference to the hairy cells of hairy-cell leukaemia.

Although the hairy cells (HCs) of hairy cell leukaemia (HCL) are now thought to be a form of activated B cell, they have long been known to possess certain monocytoid characteristics. Since the proto-oncogene c-fms is a feature of cells of the monocyte/macrophage lineage, we examined HCs for c-fms expression. We found that approximately 80% of peripheral blood HCs expressed the c-fms protein (8/8 cases). Expression of the 150 kD protein by HCs was shown using three different techniques, APAAP, immunofluorescence and immunoprecipitation, using two different antibodies. Other mature B cell lymphoproliferative disorders examined (PLL, CLL and multiple myeloma) did not express c-fms. We also examined the c-fms expression of normal B-cells: both the in vivo activated (low density) fraction of tonsil B cells and tonsil B cells activated in vitro with SAC plus IL-2 expressed the c-fms protein. As in the case of monocytes c-fms expression by HCs was shown to be down regulated by its ligand M-CSF, and by TNF alpha, both caused a decrease in the receptor expression from 80% to 30% and in the intensity of staining from 6 to 3 x 10(4) molecules/cell. However, as for monocytes, GM-CSF treatment of HCs had no effect on the expression of c-fms; alpha IFN also had no effect. M-CSF treatment of HCs also induced phosphorylation of c-fms, and a number of other proteins, on tyrosine. However, M-CSF was unable to induce HC proliferation either alone or in combination with IL-2, IL-4 or IL-6; in addition it had no effect on HC proliferation induced by SAC, anti-mu or TNF alpha. In addition, M-CSF either alone, or in combination with the above cytokines, had no effect on the differentiated state of HCs as shown by both immunoglobulin secretion and surface antigen expression. M-CSF also had no effect on the morphology or long-term survival of HCs in culture. This study therefore demonstrates that both HCs and activated B-cells express c-fms, and that M-CSF binds to and activates its receptor on HCs. Although c-fms and several other proteins were shown to be phosphorylated in response to M-CSF, the functional consequences of this phosphorylation remain unclear.

B-Lymphocytes↗
PubMed1993

Endotoxin-induced pulmonary dysfunction is prevented by C1-esterase inhibitor.

In septic shock, hypotension, disseminated intravascular coagulation, and neutrophil activation are related to the activation of the blood coagulation contact system. This study evaluates in dogs the effect of the C1-esterase inhibitor (C1-INH), a main inhibitor of the blood coagulation contact system, on the cardiovascular and respiratory dysfunction associated with endotoxic shock. Two groups were included: controls, which received Escherichia coli endotoxin, and a C1-INH group in which C1-INH was infused before E. coli endotoxin administration. In both groups, endotoxin produced hypodynamic shock; however, the decrease in the systolic index and the ventricular systolic work indexes were greater in controls than the C1-INH group. In controls, the arterial O2 partial pressure decreased by 30% and the alveolo-arterial O2 difference increased by 625%, these parameters remained unchanged in the C1-INH group. Hypoxemia was associated with increased intrapulmonary shunt, decreased blood coagulation contact factors, and decreased C3c. In contrast, C1-INH administration prevented endotoxin-induced hypoxemia, the increase in intrapulmonary shunt, and the decrease in blood coagulation contact factors. This study shows that, in dogs with endotoxic shock, pulmonary dysfunction is associated with an activation of the blood coagulation contact phase system. An inhibition of this system by C1-INH prevented the hypoxemia induced by endotoxic shock.

Animals↗
PubMed1993

Impedance transfer: acoustic impedance of the annular ligament and stapedial tendon reconstruction in otosclerosis surgery.

The resistance rebuilt around the lower tip of the piston must be the same as that created by the annular ligament of the stapes footplate. Otherwise, the threshold at which an acoustic or barotrauma is able to damage the membranes and hair cells of the inner ear will be lowered. The elasticity reestablished around the lower tip of the piston plays a part in the quality and quantity of hearing for the low frequencies up to 3 kHz. To protect the ear against acoustic traumas, an attempt to rebuild the stapedial reflex is proposed.

Acoustic Impedance Tests↗