Connexin Hemichannels: Methods for Dye Uptake and Leakage.

It is now clear that connexin-based, gap junction "hemichannels" in an undocked state are capable of opening and connecting cytoplasm to the extracellular milieu. Varied studies also suggest that such channel activity plays a vital role in diverse cell processes and abnormal hemichannel activity contributes to pathogenesis. To pursue fundamental questions in this area, investigators require methods for studying hemichannel permeability and dynamics that are quantitative, sensitive, versatile, and available to most cellular and molecular laboratories. Here we first provide a theoretical background for this work, including the role of cellular membrane potentials. We then describe in detail our computer-assisted methods for both dye uptake and leakage along with illustrative results from different cell systems. A key feature of our protocol is the inclusion of a mechanical stimulation step. We describe dye uptake, interpreted as connexin dependent, that is shown to be enhanced with reduced extracellular Ca2+, mechanically responsive, inhibited by TPA, inhibited by EL186 antibodies for Cx43 and sustained for more than 15 min following mechanical stimulation. We describe dye leakage that displays these same properties, with estimates of hemichannel numbers per cell being derived from leakage rates. We also describe dye uptake that is shown to be unaffected by a reduction in external Ca2+, insensitive to EL186 antibodies and relatively short-lived following mechanical stimulation; this uptake may occur via pannexin 1 channels expressed in the cells studied here. It is unlikely that cell damage plays a significant role in dye uptake following mechanical stimulation, given compelling results from various control experiments.

Improving preoperative medication compliance with standardized instructions.

BACKGROUND: Patient medication adherence in the perioperative setting is challenging, and failure to comply with medication instructions has serious clinical consequences. Many factors contribute to medication nonadherence, but a modifiable cause is inadequate physician instruction of patients. Variable formats, language and legibility impede patient-physician communication regarding proper use of medications. We hypothesized that the use of a standardized, electronic medical record (EMR)-derived medication instruction template would improve medication compliance on the day of surgery. METHODS: As part of an ongoing quality improvement program, our institution surveyed patient's compliance with preoperative medication instructions. A standardized template was then created within the EMR and implemented by all providers in the preoperative evaluation clinic. Compliance with medications on the morning of surgery was then reassessed by preoperative nursing staff for three months shortly after the intervention and again two years later. RESULTS: Patient adherence to preoperative medication instructions improved significantly immediately after the implementation of the template (from 83.7% to 89.7%, P=0.025). This improvement was also sustained at the two-year follow-up. Although patients' had overall good medication compliance (90% after the intervention), 71% of medication errors were made with medications with significant potential for causing complications (e.g., antithrombotic therapy). CONCLUSION: Use of standardized, EMR-generated preoperative instructions improves patient medication adherence on the morning of surgery. Even with this intervention, medication nonadherence most often involves medications that could seriously interfere with perioperative care.

Patients with vascular disease.

When conducting a preoperative evaluation of a patient with vascular disease, it is crucial to compile a detailed history and perform a thorough physical examination. One must assess for other comorbidities as well as the extent of the disease, as patients with vascular disease often have coexisting ischemic heart disease, hypertension, cerebrovascular disease, or chronic renal insufficiency. The goal of the preoperative evaluation is to identify modifiable risk factors, coordinate a treatment plan with other members of the perioperative care team, and optimize the patient's medical condition to shift the balance of risk/benefit ratio before proceeding with nonemergent surgery.