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Biomedical subjects

R Kramer

Publications and source records attributed to R Kramer.

133 records · Page 8Linked to original sources
PubMedDate not supplied

A comparison of two ophthalmic steroid-antibiotic combinations after cataract surgery.

We performed this prospective, randomised, investigator-masked, parallel-group study to compare Fluorometholone-Gentamicin eye drops with Maxitrol (dexamethasone, neomycin, polymyxin B) eye drops in the reduction of ocular bacterial flora and control of ocular inflammation after cataract surgery. One hundred and twelve (FML-Genta 54, Maxitrol 58) patients of both sexes undergoing cataract and posterior chamber lens implant surgery for visually disabling cataract were enrolled in the study and examined pre-operatively and post-operatively on days 1, 6-8 and 24-34. The baseline parameters were similar in the two study groups. The conjunctival bacterial colony count on day 6-8 post-operatively was significantly less on FML-Genta compared with Maxitrol (p = 0.033). There was no statistically significant difference between the two treatments in the degree of intra-ocular inflammation as assessed by flare and cells in the anterior chamber. Both treatments were judged to be equal in the global assessment of the success of therapy and local tolerance by the study patients and doctors. Fluorometholone-gentamicin eye drops were more effective than Maxitrol eye drops in the reduction of ocular bacterial flora while being as well-tolerated and as effective as Maxitrol in the control of ocular inflammation after cataract surgery.

Administration, Topical↗
PubMedDate not supplied

Calcium transport and compartment analysis of free and exchangeable calcium in Plasmodium falciparum-infected red blood cells.

Calcium (Ca2+) is indispensable for normal development of the various stages of the asexual erythrocytic cycle of malaria parasites. However, the mechanisms involved in Ca2+ uptake, compartmentalization and cellular regulation are poorly understood. To clarify some of these issues, we have measured total, exchangeable, and free Ca2+ in normal red cells (RBCs) and Plasmodium falciparum (FCR-3)-infected cells (IRBCs) as a function of parasite development. All three forms of Ca2+ were found to be substantially higher in IRBCs than in RBCs, and to increase with parasite maturation up to the trophozoite stage and decline thereafter. Exchangeable and free [Ca2+] in host cell and parasite compartments were determined by selectively lysing IRBCs with Sendai virus, and estimating these parameters in the lysate (host cytosol) and the pellet (parasite cytosol). Levels of both exchangeable and free [Ca2+] were found to be higher in host cytosol than in parasite cytosol. The Ca2+ gradient across the parasite membrane can be maintained by the pH gradient across this membrane by means of a Ca2+/H+ antiporter. Host cytosol free [Ca2+] reached levels known to produce structural, physiological and biochemical changes in RBCs, and could account for similar features normally seen in malaria-infected red cells. Uptake of Ca2+ into IRBCs was nonsaturable and substantially faster than the saturable Ca2+ uptake into RBCs. The rate of Ca2+ uptake across the parasite membrane was even faster suggesting that the rate-limiting step in uptake into intact IRBCs is the translocation of Ca2+ across the host cell membrane.

Animals↗
PubMedDate not supplied

Tumor inhibitory activity of anti-ras ribozymes delivered by retroviral gene transfer.

This study reports the successful introduction into tumor cells of a ribozyme directed against an oncogene using a retroviral gene delivery system. A hammerhead ribozyme that selectively targets and cleaves the activated Ha-ras (V12Ras) oncogene was delivered using a retroviral vector and expressed under the control of a transfer RNA promoter in V12Ras-transformed 3T3 murine fibroblast and rat colon epithelial cells. The expression of V12Ras messenger RNA and V12Ras P21 protein was reduced by up to 100% and 75%, respectively, in cells transduced with functional ribozyme. Reductions in V12Ras expression correlated with the stable expression of the functional ribozyme in vivo and decreased tumorigenicity in nude mice. Ribozyme constructs containing identical antisense flanking regions, but a mutant catalytic center, did not attenuate V12Ras expression or decrease the tumorigenicity of transduced tumor cells. These data support the potential therapeutic role of antioncogene ribozymes.

3T3 Cells↗