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Biomedical subjects

C Lopez

Publications and source records attributed to C Lopez.

At least 19 recordsLinked to original sources
PubMed1992

Induction of host cell protein synthesis by human herpesvirus 6.

We observed an increase in host cell protein synthesis in human cord blood lymphocytes (CBL) infected with human herpesvirus 6 relative to uninfected cultures. The magnitude of this effect could not be explained by a smaller decrease in cell number in the infected cultures. The induction of host cell protein synthesis by HHV-6 does not appear to be mediated by a stable soluble factor present in the infected cell culture supernatant. When CBL were infected with virus that had been exposed to ultraviolet irradiation (UV) for various intervals, we found that the level of increase in cell number, host protein synthesis, viral DNA and viral antigen was inversely proportional to the length of time of virus exposure to UV. No increase in cell number or host cell protein synthesis was seen in CBL infected in the presence of 50 micrograms/ml phosphonoacetic acid, an inhibitor of HHV-6 DNA replication. These results indicate that components of input virions do not induce the increased protein synthesis and that the induction is dependent on viral DNA replication.

Biological Factors↗
PubMed1991

[Cancer of the ovary].

Explore the source record for details and available documents.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1991

Decentration of intraocular lenses implanted after intercapsular cataract extraction (envelope technique).

Pseudophakos decentration produces symptoms such as glare, halos, and other visual aberrations. We have reviewed 161 eyes of patients who had an intercapsular cataract extraction with intraocular lens (IOL) implantation with a follow-up of at least six months. Mean decentration was 0.54 mm. It was 0.46 mm for the lenses implanted symmetrically in the bag, 0.65 mm for those implanted in the sulcus, and 0.91 mm for those implanted asymmetrically (bag-sulcus). The differences between the lenses fixated in the bag and those asymmetrically situated were statistically significant (P less than .001). Circular looped lenses (360-degree encircling loop) decentered less (mean 0.28 mm) than modified C-loop lenses (mean decentration 0.63 mm) and modified J-loop lenses (mean decentration 0.60 mm). These differences were statistically significant (P less than .001). The differences were also significant if we considered only the lenses implanted in the bag (mean decentration 0.20 versus 0.59 and 0.54, respectively) (P less than .0001).

Aged↗
PubMed1991

Immediate-early gene expression is sufficient for induction of natural killer cell-mediated lysis of herpes simplex virus type 1-infected fibroblasts.

Herpes simplex virus type 1 (HSV-1)-infected human fibroblast (HSV-FS) targets are susceptible to lysis by natural killer (NK) cells, whereas uninfected FS are resistant to lysis. Studies were undertaken to determine the mechanism of this preferential susceptibility. HSV-FS were not intrinsically less stable than FS, as determined by a 51Cr release assay under hypotonic shock in the presence of rat granule cytolysin and by sensitivity to anti-human leukocyte antigen class I antibody plus complement. Single-cell assays in agarose demonstrated that although similar numbers of large granular lymphocytes bound to the HSV-FS and FS targets, the conjugates with HSV-FS were lysed at a much higher frequency than those with FS. These results suggested that both targets are bound by the NK cells but only the HSV-FS were able to trigger lysis. The requirement for active virus expression was demonstrated by failure of emetine-treated HSV-FS targets or targets infected with UV-inactivated HSV to be lysed by NK effectors. To evaluate the role of viral glycoproteins in conferring susceptibility to lysis, Fab were prepared from HSV-1-seropositive sera; these Fab were unable to block lysis of the HSV-FS. Furthermore, incubation in phosphonoacetic acid failed to reduce NK(HSV-FS) activity despite sharp reductions in viral glycoprotein synthesis. Finally, targets infected with tsLB2 at the nonpermissive temperature were lysed as well as or better than targets infected with wild-type virus, indicating that HSV immediate-early gene product expression is sufficient for conferring susceptibility to lysis. We conclude that expression of nonstructural viral proteins or virally induced cellular gene products early in the course of infection rather than structural glycoproteins is required for NK lysis of HSV-FS targets.

Animals↗
PubMed1991

[Lymphaticovenous communication in the mammary gland of the female dog].

Lymphaticovenous Communications were searched in the mammary glands of 24 bitches. Injections of indian ink into the interstice of living animals were followed after death by the filling of the veins with latex and barium sulphate. Afterwards, the used techniques were: microdissection, angiography, clarification and histological section. The results obtained would seem to prove the existence of Lymphovenous Anastomoses. The roles of these communications in the canine mammary gland neoplasia are discussed.

Animals↗
PubMed1990

Thermodynamic study of the interaction of methotrexate, its metabolites, and new antifolates with thymidylate synthase: influence of FdUMP.

A microcalorimetric method was used for the direct study of the interaction of methotrexate, its metabolites, and new antifolates N10-propargyl-5,8-dideazafolate (CB 3717) and 2-methyl,2-desamino N10-propargyl-5,8-dideazafolate (CB 3819), with thymidylate synthase. We show that 7-hydroxymethotrexate and dideazafolates require the prior binding of dUMP or its fluorinated derivative FdUMP to bind to thymidylate synthase, as does methotrexate. Conversely, we show that methotrexate-G2 can interact directly with the enzyme alone. On the other hand, both dUMP and FdUMP exhibited a large cooperative effect on the affinity for thymidylate synthase of the inhibitors, and surprisingly, no significant difference was shown at this level between the natural substrate dUMP and its fluorinated derivative. It was demonstrated that this cooperative effect had an enthalpic origin. In the presence of FdUMP or dUMP, all the studied compounds except 7-hydroxymethotrexate exhibited a large negative enthalpy variation when binding to thymidylate synthase (from -44 to -91 kJ/mol). CB 3717 and methotrexate-G2 are competitors for the same protein binding site. Polyglutamation of methotrexate lead to compounds with higher affinity (association constants were 6.6 x 10(3) M-1 and 2.3 x 10(6) M-1 for methotrexate and methotrexate-G2 respectively) while hydroxylation has an unfavourable effect (association constant of 7-hydroxymethotrexate inferior to 500 M-1). Evidence for the influence of polyglutamation was also provided by the relatively low affinity of dideazofolates for thymidylate synthase (association constant equal to 1.4 and 1.7 x 10(7) M-1 for CB 3717 and CB 3819, respectively), whereas these compounds are known to be strong inhibitors of the enzyme in cells in their polyglutamated forms.

Calorimetry↗
PubMed1990

Lack of correlation between human herpesvirus-6 infection and the course of human immunodeficiency virus infection.

Human herpesvirus-6 (HHV-6) and human immunodeficiency virus (HIV) are both tropic for CD4+ lymphocytes. To determine whether HHV-6 infection affects the susceptibility to or the course of HIV infection, HHV-6 titers were measured by an anticomplement immunofluorescence assay in serum of three groups of homosexual or bisexual men: (1) those with AIDS (n = 78), (2) those with HIV-associated lymphadenopathy (LAS; n = 81), and (3) those who were HIV-seronegative (n = 55). Early and late serum samples were available for 45 men with LAS (median interval 49 months). Men with early LAS did not differ from HIV-seronegative men in either the percentage that were HHV-6-seropositive or in the distribution of titers. There was a significantly lower percentage of seropositives in AIDS patients than in the other two groups (P less than .01). LAS patients who progressed to AIDS did not differ in percentage seropositivity or distribution of titers from nonprogressors. HHV-6 titers tended to decrease over time. HHV-6 titers late in LAS were similar to those in AIDS patients. These findings suggest that it is unlikely that previous exposure to HHV-6 either predisposes to or affects the course of HIV infection.

AIDS-Related Complex↗
PubMed1990

[Topography of the lymphatic collecting ducts of the mammary glands of the dog].

The topography of the lymph drainage was examined by in vivo injections of india ink into the mammary parenchyma of 73 female dogs. Only one gland was injected at a time on each side. Only the cranial abdominal mammary gland had direct drainage to the axillary as well as to the superficial inguinal nodes. The principal routes of drainage differ for each gland. The glands on each side are completely independent as regards their lymph drainage. The cranial thoracic mammary glands on each side had their own collecting duct which led to the sternal lymph nodes. The results of this study suggest to develop a new model for the surgical extirpation of mammary tumors in the bitch.

Animals↗
PubMed1990

Identification of a nucleocapsid protein as a specific serological marker of human herpesvirus 6 infection.

Enveloped whole virions and nucleocapsids of human herpesvirus 6 (HHV-6) strain Z29 were purified from supernatant fluids of infected human cord blood lymphocytes by filtration through polyvinylpyrrolidone-treated filters, banding on a Nycondenz step gradient, and centrifugation through two successive continuous sucrose gradients. More than 20 proteins ranging in molecular weight from less than 30,000 to more than 200,000 were identified in preparations of purified whole virions labeled with [35S]methionine and [35S]cysteine. Immunogenic virion proteins of HHV-6 were identified in immunoblot assays with human immune sera, immune sera generated from mice immunized with purified whole virions or purified nucleocapsids, and a monoclonal antibody generated from a mouse immunized with purified nucleocapsids. The sera and the monoclonal antibody reacted strongly with a 101-kilodalton protein in the immunoblots, suggesting that the protein is a component of the nucleocapsid. Human sera lacking HHV-6-specific antibodies and seropositive for one or more of the other human herpesviruses failed to react with this protein, indicating that it is a specific serologic marker for HHV-6 infection.

Antibodies, Monoclonal↗
PubMed1990

Effect of acidosis on PTH-dependent renal adenylate cyclase in phosphorus deprivation: role of G proteins.

These studies examine the regulation of adenylate cyclase in renal cortical membranes from phosphate-deprived and phosphate-deprived acidotic dogs. Enzyme stimulation by parathyroid hormone (PTH) was decreased in phosphate deprivation [Vmax 1,578 +/- 169 vs. 2,581 +/- 219 pmol adenosine 3',5'-cyclic monophosphate (cAMP).mg protein-1 x 30 min-1 in controls, P less than 0.01]. Metabolic acidosis further decreased PTH-stimulated activity. Membranes from phosphate-deprived dogs showed a decrease in Gs alpha-content by cholera toxin-dependent ADP-ribosylation (174 +/- 18 arbitrary units vs. 266.4 +/- 13.6 in controls, P less than 0.01). Metabolic acidosis further decreased Gs alpha-content, P less than 0.01. Gi content by pertussis-dependent ADP-ribosylation was also lower in phosphate-deprived and phosphate-deprived acidotic animals. Gs function was examined by its property to protect the catalytic unit from inactivation by N-ethylmaleimide when preincubated with GTP gamma S. In controls, protection of inactivation was 80% of the maximal activity, whereas in phosphate deprivation protection was less than 50%. In conclusion, metabolic acidosis enhances adenylate cyclase resistance to PTH in phosphate deprivation. These alterations are associated with a decrease in the content and function of Gs alpha, suggesting a role of Gs in the renal adaptation to phosphate depletion and acidosis.

Acidosis↗
PubMed1990

[Urethral mucosal prolapse in girls. Apropos of 24 cases].

We performed surgery in twenty-four cases of urethral prolapse between 1973 and 1989 at the hospital of Fort-de-France. Urethral prolapse is a benign lesion of the terminal urethra and is predominant in young, 3 to 6 year-old black females. Vulvar hemorrhagic is the most usual initial symptom, and diagnosis is readily made by examination and urethral catheterization. Excision of the prolapsed mucosa followed by immediate muco-mucous suture permits a generally uneventful recovery without prolonged hospitalization.

Child↗