Effects of volatile anesthetics on sarcolemmal calcium transport and sarcoplasmic reticulum calcium content in isolated myocytes

BACKGROUND: The surface membrane Ca(2+)-adenosine triphosphatase and Na(+)-Ca(2+) exchanger transport Ca(2+) out of the ventricular myocyte, competing for cytosolic Ca(2+) with the Ca(2+)-adenosine triphosphatase located in the sarcoplasmic reticulum. In this study the authors examined the effects of halothane, isoflurane, and sevoflurane on Ca(2+) extrusion from the cell and sarcoplasmic reticulum Ca(2+) content. METHODS: Single myocytes from the right ventricular free wall of adult male ferret hearts were isolated, loaded with the acetoxymethyl ester of the fluorescent Ca(2+) indicator fluo-3, and electrically stimulated at 0.25 Hz to reach a steady state level of intracellular Ca(2+) stores. The effects of halothane, isoflurane, and sevoflurane (1 minimum alveolar concentration) on the peak and rate of decline of the Ca(2+) transient induced by 10 mm caffeine were examined. The peak was used as an index of sarcoplasmic reticulum Ca(2+) content, and the rate of decline was used to monitor Ca(2+) extrusion from the cell. RESULTS: During control conditions, halothane reduced the Ca(2+) content of the sarcoplasmic reticulum, isoflurane maintained it, and sevoflurane caused it to increase. Halothane did not affect Ca(2+) extrusion from the cell, but both isoflurane and sevoflurane inhibited it. When Na(+)-Ca(2+) exchange was inhibited by ionic substitution, isoflurane and sevoflurane still reduced the rate of Ca(2+) efflux from the cell. However, when the sarcolemmal Ca(2+)-adenosine triphosphatase was inhibited by carboxyeosin, isoflurane and sevoflurane had no effect on Ca(2+) efflux. CONCLUSIONS: These results suggest that isoflurane and sevoflurane inhibit Ca(2+) transport from the cell via the sarcolemmal Ca(2+)-adenosine triphosphatase. This effect seems to counteract the decrease in Ca(2+) influx through sarcolemmal L-type Ca(2+) channels and maintains sarcoplasmic reticulum Ca(2+) stores.     

Safeguarding the system. Devising a security plan for a health care network

Health care systems have continued to evolve over the past several years. Some have been successful, some have reverted back to stand-alone or affiliated hospitals, and others continue to struggle with the system concept. Security departments must identify their new roles as this evolution plays out.     

Osteogenic protein 1 device increases bone formation and bone graft resorption around cementless implants

In each femoral condyle of 8 Labrador dogs, a non weight-bearing hydroxyapatite-coated implant was inserted surrounded by a 3 mm gap. Each gap was filled with bone allograft or ProOsteon with or without OP-1 delivered in a bovine collagen type I carrier (OP-1 device). 300 microg OP-1 was used in the 0.75 cc gap surrounding the implant. After 3 weeks, the OP-1 device enhanced implant fixation by 800% (p <0.05) in the ProOsteon group, but OP-1 bad no significant effect on implant fixation in the allograft group. By adding the OP-1 device, the volume fraction of woven bone close to the implant increased from 12% to 20% (p < 0.05) in the bone allograft group and from 6% to 25% (p < 0.05) in the ProOsteon group. The volume fraction of bone allograft decreased from 29% to 9% (p < 0.05) in the OP-1 treated group versus 33% to 30% in the allograft group not treated with OP-1. No resorption of ProOsteen was found. In conclusion, OP-1 accelerates resorption of bone allograft and enhances new bone formation around cementless implants grafted with bone allograft or semisynthetic hydroxyapatite bone substitute. Our findings do not support the use of ProOsteon alone around cementless implants.     

The influence of lumbar lordosis on spinal fusion and functional outcome after posterolateral spinal fusion with and without pedicle screw instrumentation

The aim of the current study was to examine the correlation between lumbar lordosis, spinal fusion, and functional outcome in patients suffering from severe low back pain, treated by posterolateral spinal fusion with or without pedicle screw instrumentation. One hundred thirty patients were randomly allocated to posterolateral lumbar fusion with or without Cotrel-Dubousset instrumentation. Functional outcome was assessed preoperatively, and 1 and 2 years postoperatively. Lordosis angles of the lumbar spine and fusion rates were assessed at the 1- and 2-year follow-up. No difference in lordosis angle was found between the two groups at any time. Lordosis was unchanged at 2 years compared with preoperative status in both groups. In the instrumented group, nonunion (23%) was followed by a decrease in lordosis at follow-up (p < 0.05). However, in the noninstrumented group, nonunion (14%) resulted in increased lordosis (p < 0.05). No correlation was found between functional outcome and lordosis angle. The current study showed no correlation between functional outcome and lordosis angle either before or after posterolateral spinal fusion. Use of instrumentation did not influence lumbar spinal alignment compared with noninstrumented fusions. The sagittal alignment was stable both 1 and 2 years after solid fusion. The failure mode of instrumented fusions was a reduced degree of lordosis in contrast to an increased degree of lordosis in patients with noninstrumented fusion.     

Joint position sense is impaired by Parkinson's disease

The abilities of Parkinson's disease (PD) patients, taking routine medication, and of control subjects, to discriminate bilateral differences in the static angular positions of the two elbow joints were studied during passive (subject relaxed) and active (subject contracting to hold position) conditions. On each trial, one of the subject's elbows served as the reference joint (angle 60 degrees) and the other as the test joint (angular range, 54 degrees to 69 degrees, at 3 degree intervals). Subjects, with eyes closed, were required to discriminate the relative angles of the two elbows. In Experiments 1 (passive condition) and 2 (active condition), parkinsonians (n = 12) gave significantly fewer correct responses, pooled across sides, than did controls (n = 12), both in total scores across all angles and at individual test angles of 57 degrees and 63 degrees. In Experiment 3 (passive condition), derivation of conventional psychophysical variables indicated that both the difference limen (DL; threshold) and Weber ratio (WR; discriminatory sensitivity, independent of absolute stimulus values; same as DL/PSE) values of patients (n = 6) were significantly larger than those of controls (n = 6), in the absence of a significant difference between groups in the point of subjective equality (PSE). Our results provide clear evidence of a quantitative impairment of joint position sense in PD patients.     

A prospective validated model for predicting axillary node metastases based on 2,000 sentinel node procedures: the role of tumour location [corrected].

AIMS: The purpose was to identify the independent predictive factors of axillary lymph-node metastases (ALNM) in infiltrating ductal carcinoma (IFDC) and to create a prospective, validated statistical model to predict the likelihood of ALNM in patients in the present era of sentinel lymph-node (SLN) biopsy and enhanced histopathology. METHODS: Univariate and multivariate analyses of 13 clinicopathological variables (including tumour location) were performed to determine predictors of ALNM in 1659 eligible SLN biopsy procedures. A logistic regression model was developed and then prospectively validated on a second population of 187 subsequent consecutive procedures. RESULTS: Age, pathological tumour size, palpability, lymphovascular invasion (LVI), histological grade, nuclear grade, ductal histological subtype, tumour location (quadrant) and multifocality were associated with ALNM in univariate analyses (P < 0.001). Of these, only palpability and histological grade were not statistically associated with ALNM in the multivariate analysis (P> 0.05). The frequency of ALNM in upper-inner-quadrant (UIQ) tumours was 20.6%, compared with 33.2% for all other quadrants (P<0.0005). There was no statistical difference between UIQ and other-quadrant tumours in any clinicopathological variables analysed. The logistic regression model, developed based on the population of 1659, had the same accuracy, sensitivity, specificity, positive predictive value and negative predictive value when applied prospectively to the second population. CONCLUSION: Tumour size, LVI, age, nuclear grade, histological subtype, multifocality and location in the breast were independent predictive factors for ALNM in IFDC. ALNM is less frequent in UIQ tumours than in other-quadrant tumours. Our prospectively validated predictive model could be valuable in pre-operative patient discussions, although staging of the axilla in the individual patient remains necessary.     

Percutaneous biopsy and sentinel lymphadenectomy: minimally invasive diagnosis and treatment of nonpalpable breast cancer

OBJECTIVE: The purpose of this study was to determine the usefulness of the combination of percutaneous imaging-guided large-core breast biopsy and sentinel lymphadenectomy in the diagnosis and treatment of nonpalpable invasive breast cancer. MATERIALS AND METHODS: Retrospective review revealed 200 consecutive nonpalpable breast cancers diagnosed by percutaneous imaging-guided large-core biopsy and treated with surgery that included sentinel lymphadenectomy. Percutaneous breast biopsy was performed with stereotactic or sonographic guidance with an automated core needle or vacuum-assisted biopsy probe. Sentinel lymphadenectomy was performed with intradermal injection of a radioisotope and intraparenchymal injection of blue contrast agent. Technical success was defined as identification of sentinel nodes at surgery. Medical records were reviewed. RESULTS: Technical success rate was 200 (100%) of 200. In 158 (79%) of 200 cancers, sentinel nodes were tumor-free, and axillary dissection was avoided. In three (2%) of 200 carcinomas, the sentinel nodes were negative for tumor, but nonsentinel nodes suspicious on intraoperative palpation were excised and found by frozen section analysis to contain tumor. Tumor was found in sentinel nodes in 39 (20%) of 200 carcinomas; axillary dissection, performed in 31 of these 39 women, revealed additional tumor in nonsentinel nodes in seven (23%). A single surgical procedure was performed for 164 (82%) of 200 carcinomas; the breast was preserved in 191 (96%) of these 200 carcinomas. CONCLUSION: Percutaneous imaging-guided large-core breast biopsy and sentinel lymphadenectomy provide a minimally invasive approach to the diagnosis and treatment of women with nonpalpable invasive breast cancers.