The Utility of Peers and Trained Raters in Technical Skill-based Assessments a Generalizability Theory Study

OBJECTIVE

The gold standard for evaluation of resident procedural competence is that of validated assessments from faculty surgeons. A provision of adequate trainee assessments is challenged by a shortage of faculty due to increased clinical and administrative responsibilities. We hypothesized that with a well constructed assessment instrument and training, there would be minimal differences in procedural assessments made by near-peer resident raters (RR), faculty raters (FR), and trained raters (TR).

DESIGN

Deidentified videos of residents performing hand-sewn (HA) and stapled (SA) anastomoses were distributed to blinded reviewers of 3 types. Intra-class correlation (ICC) of RR, FR and TR assessments was determined for each procedure. A fully-crossed design was used to examine the internal structure validity in a generalizability study. A Decision study was performed to make projections on the number of raters needed for a g-coefficient > 0.70.

SETTING

This study was conducted within a private academic institution, using the creation of intestinal anastomoses as the procedural model.

PARTICIPANTS

Raters consisted of residents who were untrained to the assessment (UTA) tool, UTA faculty surgeons, and individuals with training.

RESULTS

Twenty nine videos were reviewed (15 HA and 14 SA) by a total of 9 video reviewers (4 RR, 2 FR, and 3 TR). HA ICC values were 0.84 (Confidence Interval [CI]:0.81-0.87) for RR, 0.89 (CI:0.86-0.92) for FR, and 0.88 (CI:0.86-0.90) for TR. SA ICC values were 0.77 (CI:0.72-0.80) for RR, 0.79 (CI:0.75-0.83) for FR, and 0.86 (CI:0.83-0.88) for TR. The g-coefficient was RR = 0.72, FR = 0.85, and TR = 0.77 for HA; and RR = 0.33, FR = 0.38, and TR = 0.4 for SA. The D-study indicated that at least 2 raters of any type were needed for HA and > 11 FR for SA.

CONCLUSIONS

Faculty without training have high assessment agreement. Peers for surgical skills assessment is an option for formative evaluation without training. Training to assessment tools should be performed for any assessment, formative or summative, for the optimal evaluation of procedural competence.

Preclinical Surgical Preparatory Course and the NRMP Match: Early Exposure and Surgical Recruitment a 10-Year Follow-Up

OBJECTIVE

Many medical students mentally commit to specialties prior to entering clerkships. This is why early preclinical interactions with surgical specialties, through mentorship and/or interest groups, increases the opportunity to nurture enthusiasm for surgery. In 2007, a course providing preclinical medical students with introductory surgical skills training and preparation for the surgical environment ("SURG205") was established at our institution. The course underwent a major revision in 2016, increasing intraoperative mentorship by matching students to surgical attendings and requiring students to scrub into operative cases together. We anticipate that the positive surgical experiences created by the course will lead to further development and enhancement of student interest in surgical specialties-interest that we hypothesized would reflect in their National Resident Matching Program (NRMP) Match outcomes.

DESIGN

NRMP results from 2010 to 2019 were cross-referenced with a database of students who participated in the SURG205 course from 2007 to 2016. With this, we examined the correlation between student participation in SURG205 and surgical specialty match. Descriptive statistics were used to review the trends of the NRMP results, and Pearson's correlation was used to determine the relationship and its significance.

SETTING

This study was conducted in a single private medical school in California.

PARTICIPANTS

Specialties considered "surgical" included: General Surgery, integrated programs-such as Plastic, Thoracic, or Vascular surgery, Obstetrics and Gynecology, Orthopedic Surgery, Otolaryngology, Neurosurgery, and Urology. All other specialties were considered nonsurgical. Students identified as having participated in SURG205 and who then also took part in the NRMP.

RESULTS

Seven hundred eighty students underwent the Match process from 2010 to 2019. 144 (18.5%) of these students participated in SURG205 between 2007 and 2016. Each Match class ranged in size from 62 to 91 (median = 77.5, IQR = 14.5) students. (Table 1) Two-hundred and nineteen students (28.1%) matched into a surgical specialty, of which 34 (15.5%) selected general surgery. From 2010 to 2019 the rate of students who matched into surgical specialties averaged 28.1% per year with a slight nonstatistically significantly increasing trend over that time period R² = 0.30 (p = 0.09; Fig. 1). There was a significant increase in trend in proportion of students who took the course and matched into any specialty between 2010 and 2019 (R² = 0.85, p = 0.0002; Fig. 2). And, there was a statistically significant positive relationship between students taking the course and matching into a surgical specialty (R² = 0.63, p = 0.01; Fig. 3).

CONCLUSION

Our results highlight the increasing tendency of students who pursue surgical specialties having previously participated in this early exposure courses. Not only is student interest created and encouraged through positive mentorship experiences, but that interest may be associated with increases in application rates and eventual match into the specialty. General surgery training programs might consider these trends when designing courses to ease transitions into first-year residency positions-such as fourth-year surgical boot camps, surgical procedure-based anatomy courses, and mentorship frameworks. This information further justifies the cost and time commitment required to administer these programs for students.

Glycemic Control in Surgery Patients: A Cross-Specialty Educational Intervention for Residents

This article was migrated. The article was not marked as recommended. Introduction: Glycemic control in surgical patients with diabetes is critical to their recovery. Residents play a significant role in the management of these patients and glucose control while inpatient. Surgery residents are not trained in diabetes management and there is a significant knowledge deficit of first year surgical residents with regard to perioperative and inpatient diabetes management. Methods: Together with the endocrinology team, we developed an inpatient diabetes management curriculum for incoming surgical residents. The session was incorporated into a larger 2-day intern preparation course given in anticipation of the start of residency. The course is taught by surgery attending physicians and surgical residents and is meant to prepare new interns for common problems that they will encounter on the patient floors. Results: The curriculum was highly rated by residents led to significantly greater comfort and versatility with the management of various types of insulin regimens in surgical patients. Discussion: This study demonstrates the effectiveness of a brief intervention in developing, managing and altering insulin regimens by surgical residents through a multidisciplinary approach. Our curriculum can be easily adopted for other learner groups including all other interns and medical students prior starting their clerkships. The materials created for the curriculum can be downloaded free of charge to be used by other programs.

Validity Evidence for a Knowledge Assessment Tool for a Mastery Learning Scrub Training Curriculum

PURPOSE

To examine the validity evidence for a scrub training knowledge assessment tool to demonstrate the utility and robustness of a multimodal, entrustable professional activity (EPA)-aligned, mastery learning scrub training curriculum.

METHOD

Validity evidence was collected for the knowledge assessment used in the scrub training curriculum at Stanford University School of Medicine from April 2017 to June 2018. The knowledge assessment had 25 selected response items that mapped to curricular objectives, EPAs, and operating room policies. A mastery passing standard was established using the Mastery Angoff and Patient-Safety approaches. Learners were assessed pre curriculum, post curriculum, and 6 months after the curriculum.

RESULTS

From April 2017 to June 2018, 220 medical and physician assistant students participated in the scrub training curriculum. The mean pre- and postcurriculum knowledge scores were 74.4% (standard deviation [SD] = 15.6) and 90.1% (SD = 8.3), respectively, yielding a Cohen's d = 1.10, P < .001. The internal reliability of the assessment was 0.71. Students with previous scrub training performed significantly better on the precurriculum knowledge assessment than those without previous training (81.9% [SD = 12.6] vs 67.0% [SD = 14.9]; P < .001). The mean item difficulty was 0.74, and the mean item discrimination index was 0.35. The Mastery Angoff overall cut score was 92.0%.

CONCLUSIONS

This study describes the administration of and provides validity evidence for a knowledge assessment tool for a multimodal, EPA-aligned, mastery-based curriculum for scrub training. The authors support the use of scores derived from this test for assessing scrub training knowledge among medical and physician assistant students.

Tracking Surgical Education Survey Research Through the APDS Listserv

OBJECTIVE

Survey-based studies are cornerstones in medical education research. The Association of Program Directors in Surgery (APDS) listserv offers a method to contact program directors (PD) and residents for such research. To facilitate research beneficial to the APDS, improve the quality of survey-based research and minimize survey fatigue, the APDS research committee (ARC) developed a survey review process to grant access to the listserv for research. This study was conducted to determine the impact of the review process on the quality of survey-based research and eventual publication.

DESIGN

This log was systematically reviewed identifying publications resulting from accepted surveys. Publications were categorically analyzed to determine the components of their survey tool methodology, response rate (RR), and medical education research study quality instrument (MERSQI) score.

SETTING

The ARC used a 2-reviewer peer-review process for survey distribution requests. The request was either accepted, rejected, or returned for revision. Accepted surveys were distributed through the listserv with an ARC attestation of approval.

PARTICIPANTS

A log of all survey requests maintained from 2014 to 2017 and subsequent publications.

RESULTS

Thirty-five requests were accepted (40%), 30 were reviewed discovering 10 surveys that led to 12 publications (publication rate of 33%). The average RR was 60% (SD = 29%). Detailed explanations of survey development strategies were reported in 5 (42%), consisting of methods building validity evidence such as expert consensus, modified Delphi method, and pilot group sampling. Half of study participants were PD (50%). MERSQI scores averaged 10 (SD = 1.6).

CONCLUSION

Based on those survey research published to date, the ARC survey peer-review process has enabled most accepted surveys to achieve adequate RR. Although the pool of accepted requests is small, it does highlight areas of improvement. With further refinement of the process, including questioning the survey development methods, the process and listserv can be a powerful tool for further research.

Development and Implementation of a Hands-on Surgical Pipeline Program for Low-Income High School Students

This qualitative study describes the development and implementation of a hands-on surgical pipeline program for low-income high school students.

Transfemoral Venous Access Facilitates Upper Extremity Dialysis Interventions: Procedural Success and Clinical Outcomes

PURPOSE

To report technical success and clinical outcomes of transfemoral venous access for upper extremity dialysis interventions.

MATERIALS AND METHODS

A total of 15 patients underwent a transfemoral venous approach for fistulography (n = 4; 27%) or thrombectomy (n = 11; 73%) over a 14-month period. Access characteristics, sheath size, thrombectomy method, angioplasty site, fluoroscopy time, radiation dose, technical and clinical success, complications, and post-intervention primary and secondary patency rates were recorded.

RESULTS

Access type included arteriovenous fistulas (n = 10; 67%) and grafts (n = 5; 33%). The most common configuration was brachio-brachial (n = 6; 38%). Mean age of access was 37 months. Mean prior interventions were 4. Right CFV access was used in all patients using 6-8-French (most common: 7-French [n = 10; 67%]) sheaths. Most thrombectomies (n = 11; 73%) required both pharmacologic and mechanical maceration (n = 9; 82%). All accesses required angioplasty to treat underlying stenosis at the outflow vein (n = 12; 80%) or arteriovenous anastomosis (n = 9; 90%). Mean fluoroscopy time was 26.43 min. Air kerma and dose area product were 178.06 ± 225.77 mGy and 57,768.83 ± 87,553.29 μGym², respectively. Procedural and clinical success rates were 93% and 80%, respectively. Technical failure was due to persistent stenosis in one patient. Clinical failure was due to unsuccessful dialysis immediately following intervention in three patients. Mean post-intervention primary patency and secondary patency durations were 2.8 and 4.8 months, respectively. Primary patency rates at 1 and 3 months were 50% and 35%, respectively. Secondary patency rates at 1 and 3 months were 58% and 30%, respectively.

CONCLUSION

A transfemoral venous approach for intervention of upper extremity dialysis accesses may be a valuable adjunct to traditional approaches.

Introductory Surgical Skills Course: Technical Training and Preparation for the Surgical Environment

Introduction

Early exposure to surgery in a positive learning environment can contribute to increased student interest. The primary objectives of this study included developing increased comfort in the operating room (OR) environment, confidence in surgical skills, and mentorship for students interested in surgery.

Methods

The course comprised seven 2-hour sessions covering both nontechnical and technical skills facilitated by attending and resident surgeons. Sessions included nontechnical skills training, basic knot tying and suturing, laparoscopic surgical skills, and high-fidelity operative simulations on animal and cadaver models. The curriculum also matched students with faculty mentors in order to scrub into operative cases. Surveys assessing self-reported comfort in the OR, confidence levels in surgical skills, and whether students had mentors in surgery were distributed before and after the course.

Results

Thirty preclinical medical students were enrolled in the course in 2016 and an additional 41 students in 2017. Results showed increased confidence in all skills and in comfort in the OR, as well as increased surgeon mentorship. Thirty-two students who completed the course entered clinical rotations in 2018 and, when surveyed, reported increased confidence in the aforementioned domains and in their preparedness for their surgery clerkship, compared to 49 peers who had not completed the course.

Discussion

The course successfully increased comfort in the OR, increased confidence in performing surgical skills, and provided students with mentors in surgery, all of which will hopefully foster positive experiences during their surgery clerkship and ultimately increase their consideration of surgery as a career.

Single ZnO nanobelt based field effect transistors (FETs)

Electrical properties of single ZnO nanobelt have been examined by fabricating single nanobelt based field effect transistors (FETs). The ZnO nanobelts were grown via non-catalytic simple thermal evaporation process by using metallic zinc powder in the presence of oxygen. The detailed structural and optical characterizations confirmed that the grown nanobelts are well-crystalline with the wurtzite hexagonal phase and exhibiting good optical properties. The passivation effect on the electrical characteristics of the as-grown nanobelts was also evaluated by passivating the fabricated FETs with polymethyl methacrylate (PMMA). The passivated single ZnO nanobelt based FETs exhibited higher electrical performance as compared to non-passivated FETs due to reduction in the physically absorbed chemisorbed species such as O-, O2-, O2, or OH- etc. The field effect mobility (micro(eff)) of the fabricated nanobelt based non-passivated and passivated FETs was estimated to be approximately 21.3 and 59 cm2/V x s, respectively. Moreover the carrier concentration and peak transconductance of the fabricated non-passivated and passivated FET were calculated to be approximately 8.73 x 10(17) and approximately 1.86 x 10(18) cm(-3) and approximately 0.76 and 1.4 microS, respectively. This work offers substantial opportunities for further practical electronics and photonics nanodevice applications of ZnO based nanostructures.

Comparison between the electrical properties of ZnO nanowires based field effect transistors fabricated by back- and top-gate approaches

Large-quality, well-crystallized growth of ZnO nanowires was done via non-catalytic thermal evaporation process on silicon substrate only by using metallic zinc powder and oxygen as source materials for zinc and oxygen, respectively. The electrical properties of the as-grown ZnO nanowires were examined by fabricating a single nanowire based FETs which were fabricated via two approaches, i.e., back- and top-gate approaches by using electron beam lithography (EBL) and photolithography processes. ZnO FETs electrical properties were characterized by I(DS)-V(DS) and I(DS)-V(GS) measurement. The fabricated single ZnO nanowire based FETs by back- and top-gate approaches exhibited field effect mobilities of approximately 4.25 and approximately 12.76 cm2/Vs, respectively. Moreover, the carrier concentrations for the fabricated back- and top-gate FETs were approximately 1.6 x 10(17) and approximately 1.37 x 10(18) cm(-3), respectively. From our studies it was observed that the fabricated top-gate FETs exhibited higher and good electrical properties as compared to ZnO nanowire FETs fabricated using back-gate approaches.

Comparison of SAR (sodium adsorption ratio) between RO and NF processes for the reclamation of secondary effluent

Secondary effluent reclamation and reuse has been considered as an alternative for agricultural irrigation water. Whilst all constituents in the reclaimed wastewater could affect plant growth and soil characteristics, the most important parameters for agricultural irrigation are salinity and SAR (Sodium Adsorption Ratio). Salinity affects the availability of crop water and sodium causes clay soils to disperse. Membrane technologies, especially NF (Nano-Filtration) and RO (Reverse Osmosis), have played in a key role reclaiming the secondary effluent. RO can remove monovalent and divalent cations simultaneously. However NF processes reject preferably divalent cations and most monovalent ions are allowed to pass through the NF membranes. This could make them have different SAR values for both NF and RO processes. Therefore the primary objective of this study is to examine if the SAR values of the reclaimed water could be changed while they undergo NF and RO processes. The measured SAR values of the secondary effluent, NF permeate, and RO permeate were 1.78, 4.67, and 0.72 respectively. The SAR value after NF (4.67) increased to more than twice that of the feed solution, whereas the SAR of the RO permeate decreased to 0.72. In general, the higher SAR the water has, the greater risk the soils have. Although the SAR value after NF was within the safe range, this increased SAR value will affect permeability of soil, thus limiting the reclaimed wastewater use for as agricultural irrigation water. Consequently, when the NF system is used for the reclamation of the secondary effluent, SAR has to be examined first because potentially it tends to increase the SAR value.

Anatomical study concerning the origin and course of the pectoral branch of the thoracoacromial trunk for the pectoralis major flap

The patterns of the feeding vessels to each muscle determine the extent of their safe transposition and the muscle's value as a pedicled flap in reconstructive surgery. This study aimed to demonstrate the point of origin and the intra- and submuscular course of the pectoral branch of the thoracoacromial trunk (TAT) for pectoralis major (PM) flap surgery. Seventy sides of the PM were dissected based on a clinical reference line that has been used for several decades. The branching point of the TAT from the axillary artery was located lateral to the midclavicular line on the right-sided specimens (100%) and medial to the midclavicular line on the left sides (86%). The branching patterns of the pectoral branch to the PM muscle from the TAT were classified into three types. In type I the pectoral branches originated directly from the TAT (55 cases, 78.6%). In type II (11 cases, 15.7%) and type III (4 cases, 5.7%) the pectoral branch divided from the medial and lateral pedicle of the TAT, respectively. The course of the pectoral branch from the TAT in the PM was categorized into three patterns according to the degree of proximity to the midclavicular line. In 49 cases (70%), the pectoral branch in the PM ran within 1 cm of the midclavicular line. The other cases ran 2 cm (20 cases, 29%) and 3 cm (1 case, 1%) from the midclavicular line, respectively. These results provide topographic data of the pectoral branch based on anatomical landmarks, and will be useful in surgical planning as well as the procedure for PM flap surgery.

Topographic anatomy of the lingual nerve and variations in communication pattern of the mandibular nerve branches

We made a thorough observation of the morphology and course of the lingual nerve (LN) and inferior alveolar nerve (IAN) to clarify their topographical relationships in the infratemporal fossa and in the paralingual area. Thirty-two Korean hemi-sectioned heads were dissected macroscopically and microscopically from a clinical viewpoint. On the 32 tracings on the radiograph, the average distance between the retromolar portion and the LN was 7.8 mm, and no case was found where the LN ran above the alveolar crest as passing along the mandibular lingual plate. The bifurcation of the LN and IAN was located around the mandibular notch, inferior to the otic ganglion in 66% of the cases, and a plexiform branching pattern of the mandibular nerve was observed in only two cases. The bifurcation spot of the LN and IAN was located 14.3 mm inferior to the foramen ovale and 16.5 mm superior to the tip of hamulus. Collateral nerve twigs from the LN to the retromolar area were observed in 26 cases (81.2%), with an average of one nerve twig. We observed four types of variations in terms of communication pattern. In four specimens, the mylohyoid nerve passed through the mylohyoid muscle and connected with the LN. In other four specimens, the IAN communicated with the auriculotemporal nerve. We also observed another type of variational communication between the IAN and the nerve to the lateral pterygoid (LPt); this was observed in only one specimen, and it could be predicted that motor innervation from the nerve to the LPt was transmitted via the mental nerve to the depressor anguli oris. Another type was observed where the IAN divided into two branches with the posterior branch being partially entrapped by the LPt muscle fibers.

Mandibular invasion of lower gingival carcinoma in the molar region: its clinical implications on the surgical management

The spread pattern of a tumour and its extent in the mandible are important in the management of gingival cancer. Sixteen patients with gingival squamous cell carcinoma (SCC) involving the mandible in the molar region were included in this study. Resection specimens of the mandibular bone and adjacent cancer were histologically analysed to identify the type and characteristics of invasion and were compared with the radiological features. Our results showed that the actual width of invasion was underestimated to a greater extent than the actual depth of invasion. For horizontal aspects, four dentate cases had horizontal intramedullary spread underneath intact mucosa or cortical bone extended from the main foci of tumour that infiltrated through the occlusal surface. For vertical aspects, nerve invasion took place in only one of 16 specimens, while five cases showed downward infiltration beyond the inferior alveolar canal without nerve involvement, so that the pattern of tumour spread was mostly transmedullary rather than perineural in previously non-irradiated cases. These cases with deep infiltration showed the infiltrative type of invasion in the dentate mandible. And when the tumour was related with previous dental extractions or curettage, it tended to be more extensive than what was predicted from an imaging point of view. These pathological and clinical features affecting the tumour spread should be considered in the management of gingival SCC in the molar region.

Critical role of dipeptidyl peptidase IV in neuropeptide Y-mediated endothelial cell migration in response to wounding

Recently, we have discovered that neuropeptide Y (NPY), a sympathetic neurotransmitter, is also present in human umbilical endothelial cells (HUVECs), and is potently chemotactic and angiogenic by acting on one or several of Y1-Y5 receptors. In HUVECs, NPY is co-localized with dipeptidyl peptidase IV (DPPIV) which cleaves Tyr(1)-Pro(2) from NPY(1-36) to form NPY(3-36) resulting in the formation of a non-Y1 receptor agonist, which remains angiogenic. Presently we studied the effects of DPPIV's blockade using monoclonal antibodies (mAbs) on migration of HUVECs in response to NPY(1-36) or NPY(3-36) following cell wounding. Both peptides caused similar dose-dependent increases in cell migration (+80% at 0.1 nM) 12 h after wounding. DPPIV mAbs, E19 and E26, significantly reduced HUVEC's migration below that of the untreated cells, and blocked responses to NPY(1-36) but not NPY(3-36). Enhanced expression of DPPIV was found in the migrating cells and in cells with their protrusions at the edge of the wound (immunostaining and Western blot). Thus, DPPIV's expression is stimulated by endothelial wounding and its enzymatic activity is required for NPY-mediated chemotaxis. Furthermore, this suggests that non-Y1 receptors activated by NPY(3-36) (Y2, Y3 and/or Y5) mediate angiogenic effects of NPY.

Early fatigue failures of cemented, forged, cobalt-chromium femoral stems at the neck-shoulder junction

Femoral component fracture is a rare but well-documented complication after total hip arthroplasty. Historically, most stem fractures have occurred at the middle third of the implant, where proximal stem loosening and solid distal stem fixation result in cantilever bending and eventual fatigue failure. In contrast, we report 2 early fatigue failures of well-positioned, well-fixed, cemented, forged, cobalt-chromium femoral components at the neck-shoulder junction. A contributing factor to the implant failures was heavy laser etching in a region of the implant subjected to high stresses, leading to decreased fatigue resistance and subsequent fracture.

Two novel diterpenoids, erinacines H and I from the mycelia of Hericium erinaceum

Novel diterpenoids, erinacines H (1) and I (3), were isolated from the cultured mycelia of Hericium erinaceum. The structures of the compounds were determined by interpretation of the spectral data. Erinacine H showed stimulating activity of nerve growth factor (NGF)-synthesis.

Suppression of D-galactosamine-induced liver injury by mushrooms in rats

Six species of edible mushroom were found to suppress D-galactosamine-induced enhancement of plasma alanine and aspartate aminotransferase activities when powdered mushrooms were added to the diet (5%) and fed to rats for 2 wk. Grifola frondosa exhibited the most potent effect in a dose-dependent manner. A significant effect was observed only from the water-soluble low-molecular-weight fraction of G. frondosa. The results indicate that several mushrooms possess a protective effect against liver injury induced by D-galactosamine.

ATP-sensitive potassium channels in freshly dissociated adult rat striatal neurons: activation by metabolic inhibitors and the dopaminergic receptor agonist quinpirole

The characteristics of adenosine 5'-triphosphate (ATP)-sensitive K+ channels in acutely isolated striatal neurons from adult rats were examined. Neurons had a resting membrane potential of -53.9+/-1.2 mV (n=66), with evoked or spontaneous action potentials firing at 10+/-0.7 Hz, and large inwards and outwards whole-cell currents. In cell-attached patches with a high [K+] in the pipette, a voltage-independent, ATP-insensitive 16.5+/-1.5 pS channel was observed in 375 out of 452 cells. Bath application of Na+-azide (0.5-2 mM) to 108 neurons revealed another 145.7+/-3.5 pS (LKATP) channel in 65 neurons; this channel was blocked by tolbutamide. The LKATP channel exhibited a high open probability (Po, 0.8+/-0.05) at 0 mV pipette potential. Varying the pipette [K+] shifted the reversal potential of LKATP, showing the channel's K+ selectivity. Cytoplasmic ATP (ATPi) reversibly inhibited LKATP, with an inhibitory constant (Ki) of 0.12 mM. LKATP was sensitive to intracellular Ca2+ but insensitive to iberiotoxin. In 25% of cell-attached patches, the presence of quinpirole in the pipette opened a third type of channel (90.6+/-1.7 pS, termed D2KATP). Sulpiride, a dopamine D2-receptor antagonist, inhibited D2KATP. ATPi reversibly inhibited D2KATP, with a Ki of 0.212 mM. The Na+-azide- or quinpirole-induced current caused a tolbutamide-sensitive membrane hyperpolarization and a marked reduction in action potential frequency. We propose that ATP-sensitive K+ channels play a metabolism-dependent role in striatal neurons.

The analysis of correlated panel data using a continuous-time Markov model

We consider the analysis of correlated panel data in which two or more correlated multistate processes are periodically observed on each individual and the exact transition times between states are unknown. We describe a procedure that models each process marginally under a time-homogeneous Markov model allowing for covariates. The resulting estimators are shown to be asymptotically jointly normal with a covariance matrix that can be consistently estimated. Simultaneous inference procedures are also proposed. Methods are illustrated using data from an AIDS clinical trial to compare the toxic effects of two treatments on two hematologic variables, hemoglobin and absolute neutrophil count.

Ionic mechanism of ibutilide in human atrium: evidence for a drug-induced Na+ current through a nifedipine inhibited inward channel

This study examined the ionic mechanism of ibutilide, a class III antiarrhythmic in clinical use, on freshly isolated human atrial cells. Cells had resting potentials of -71.4 +/- 2.4 mV, action potentials with overshoot of 36.8 +/- 1.8 mV, duration of 265 +/- 89 msec at 90% repolarization and slow repolarization (n = 16). Ibutilide, at 10(-7) M, markedly increased action potential duration. Four types of outward currents were detected: Ito, Iso, a delayed rectifier and IK1. Ibutilide had no inhibitory effect on these outward currents at 10(-7) M (n = 28). In K(+)-free solutions and -40 mV holding potential, mean peak inward current at 20 mV was -1478 +/- 103 pA (n = 12). Ibutilide increased this current to -2347 +/- 75 pA at 10(-7) M, with half maximal effect (Kd) of 0.1 to 0.9 nM between -10 and +40 mV (n = 21). At similar concentrations, the drug increased APD, with Kd of 0.7 and 0.23 nM at 70 and 90% repolarization, respectively (n = 8). Ibutilide shifted the mid-point of the steady-state inactivation curve from -21 to -12.2 mV (n = 6), and reduced current decline during repetitive depolarization (n = 5). The drug induced inward current was carried by Na+o through a nifedipine inhibited inward channel because Na+o removal eliminated the effect, and nifedipine abolished the inward current and the drug induced APD prolongation. We propose that a Na+ current through the L-type Ca++ channel mediates ibutilide's potent clinical class III antiarrhythmic action.

Does low dose dopamine attenuate the decrease of renal function in the treatment of patients under controlled mechanical ventilation with positive end expiratory pressure?

Controlled mechanical ventilation (CMV) with positive and expiratory pressure (PEEP) is often used to improve the pulmonary gas exchange in patients with acute respiratory distress syndrome. However, this ventilatory technique may induce hemodynamic and hormonal changes which may lead to vital organ dysfunction, such as oliguria. Low dose dopamine, acting as a dopaminergic receptor agonist, may improve vital organ perfusions, i.e. renal, mesenteric and coronary perfusions. The purpose of this current study was to evaluate the effects of low dose dopamine on renal function and hemodynamic change during controlled mechanical ventilation with PEEP. The study was performed on 10 patients treated with PEEP in the surgical intensive care unit. Starting with 0 cmH2O of PEEP and adding 4 cmH2O of PEEP at 4-hour intervals until it reached 12 cmH2O of PEEP, dopamine, 2 ug/kg/min, was selectively, administered, intravenously during the last two hours of each four hour intervals. Following each procedure, hemodynamic parameters, urine output, creatinine clearance and fractional excretion of sodium were measured. The cardiac index and mean arterial pressure had both decreased, but the mean pulmonary arterial pressure was increased at 12 cmH2O of PEEP compared with 0 cmH2O of PEEP in both groups with and without low dose dopamine. The main result of this study was that low dose dopamine attenuated the decrease of the cardiac index, urine output and creatinine clearance induced by mechanical ventilation with PEEP at 12 cmH2O.