Chronic drug infusion into the scala tympani of the guinea pig cochlea.

This research describes a unique, effective and inexpensive delivery system to provide discrete quantities of drugs on a chronic basis to the inner ear. The amount of the drug administered and specific timing of each administration are under investigator control. A micro-injection system mounted atop an animal's head is shown to permit repeated application of agents which effectively block neural responsiveness (tetrodotoxin) on a daily basis for periods up to 2 weeks. Cannulation of the inner ear and chronic delivery of control substances (artificial perilymph) do not affect function. This system may be used to administer drugs to other compartments of the body (e.g., the brain) on a chronic basis for neurophysiologic and neuropharmacologic investigations.     

Assessment of clinical significance of anti-Ge in an untransfused man

A 19-year-old, untransfused Melanesian man from Papua New Guinea was admitted to the hospital for repair of an atrial septal defect. His serum contained an alloantibody that reacted strongly on the indirect antiglobulin test and was identified as anti-Ge. Gerbich-negative blood was transfused following urgent surgery. A 51Cr red cell survival study performed 2 weeks after surgery yielded zero survival of Gerbich-positive cells after 24 hours. A monocyte-driven, antibody-dependent, cell-mediated cytotoxicity assay performed on both pretransfusion and posttransfusion serum samples and on concentrated serum showed less than 1 percent specific lysis of Gerbich-positive cells. This did not correlate with the indication of clinical significance predicted by the 51Cr study. Red cell adherence and phagocytosis, not evident in a monocyte monolayer assay using native serum, were demonstrable in 16 percent of monocytes by the use of concentrated serum.     

A novel physiological testing device to study knee biomechanics in vitro

Background

To properly study knee kinetics, kinematics and the effects of injury and surgical treatment in vitro, the knee should be constrained as little as possible, while imposing physiological loads. A novel dynamic biomechanical knee system (BKS) is presented here. The aim of this study was to test the feasibility and reproducibility of the system and demonstrate its features with an Anterior Cruciate Ligament (ACL) lesion model.

Human fibroblasts downregulate plasminogen activator inhibitor type-1 in cultured human macrovascular and microvascular endothelial cells

We have previously reported that plasminogen activator inhibitor type-1 (PAI-1) expression in endothelial cells (ECs) can be modulated differently by smooth muscle cells depending on their origin. Human pulmonary artery smooth muscle cells (HPASMCs) strongly downregulated PAI-1 expression in ECs. Fibroblasts (FBs) are another cell type that could come in close contact with ECs. Therefore, it was the aim of this study to investigate whether FBs could also influence the fibrinolytic potential of ECs. As in the case of HPASMCs, PAI-1 antigen produced by human umbilical vein ECs (HUVECs) cocultured with human skin FBs (HSFBs) was significantly lower as compared with the sum of PAI-1 secreted by the respective cell types cultured separately. Not only HUVECs but also human skin microvascular ECs (HSMECs) responded in a dose-dependent way to serum-free conditioned media (CM) from HSFBs from one individual donor. Similar results were obtained when CM from HSFBs from four other individual donors were used. PAI-1 mRNA decreased in HUVECs incubated for 6 hours with HSFB-CM to 24% to 55% of control, depending on the preparation of HSFBs used. A significant PAI-1 downregulatory effect was only observed when CM from low-passage HSFBs (up to passage no. 5) was used, whereas no reduction in EC PAI-1 production was observed with CM obtained from HSFBs in passage no. 8. This PAI-1 downregulatory activity present in HSFB-CM was heat-labile and had a molecular mass of approximately 5 kD. When CM from HPASMCs was analyzed in the same way, an almost identical elution profile was found. In conclusion, our data showed that FBs can decrease the expression of PAI-1 in ECs. Such an effect could be operative during wound-healing and at other capillary sites where FBs could render ECs profibrinolytic, thereby facilitating processes requiring an increase in proteolytic activity such as EC migration and proliferation.     

A monoclonal antibody-defined membrane antigen complex is required for neutrophil-neutrophil aggregation

We examined the aggregation responses of normal neutrophils treated with the murine monoclonal antibody (MoAb) 60.3. Addition of MoAb 60.3 to normal neutrophils produced dose-dependent inhibition of neutrophil aggregation in response to phorbol myristate acetate, zymosan-activated plasma, and N-formyl-methionylleucylphenylalanine. We conclude that the membrane glycoprotein complex recognized by MoAb 60.3--designated CDw18- -is required for neutrophil-neutrophil aggregation in vitro.     

Rate control is more cost-effective than rhythm control for patients with persistent atrial fibrillation--results from the RAte Control versus Electrical cardioversion (RACE) study.

Aims To evaluate costs between a rate and rhythm control strategy in persistent atrial fibrillation. Methods and results In a prospective substudy of RACE (Rate control versus electrical cardioversion for persistent atrial fibrillation) in 428 of the total 522 patients (206 rate control and 222 rhythm control), a cost-minimisation and cost-effectiveness analysis was performed to assess cost-effectiveness of the treatment strategies. After a mean follow-up of 2.3+/-0.6 years, the primary endpoint (cardiovascular morbidity and mortality) occurred in 17.5% (36/202) of the rate control patients and in 21.2% (47/222) of the rhythm control patients. Mean costs per patient under rate control were euro 7386 and euro 8284 under rhythm control. Cost-effectiveness analysis showed that per avoided endpoint under rate control, the cost savings were euro 24944. Under rhythm control, more costs were generated due to electrical cardioversions, hospital admissions and anti-arrhythmic medication. Costs were higher in older patients, patients with underlying heart disease, those who reached a primary endpoint and women. Heart rhythm at the end of study, did not influence costs. Conclusions Rate control is more cost-effective than rhythm control for treatment of persistent atrial fibrillation. Underlying heart disease but not heart rhythm largely accounts for costs.