Molecular characterization of a consistent 4.5-megabase deletion at 4q28 in prostate cancer cells

Spectral karyotyping of prostate cell lines LNCaP, DU145, PC3, and 22RV demonstrated structural chromosome rearrangements involving the distal long arm of chromosome 4. In all but 22RV, these are nonreciprocal translocations between chromosomes 4 and 10. In 22RV, an apparently reciprocal t(2q;4q) is seen. Fluorescence in situ hybridization analysis of the chromosome 4 translocation breakpoints demonstrated that deletions were associated with all of the translocations, resulting in a net loss of chromosome material. Overlapping deletions in 4q28 approximately 34 were seen in LNCap, DU145, and 22RV, which defined an approximately 4.5-megabase pair common region of deletion. The deletion in PC3 was more proximal on 4q, involving the 4q21 approximately q26 region. A meta analysis of high-resolution definition of losses of chromosome material from published studies demonstrates that loss of 4q material may occur in at least 50% of primary tumors. This analysis defines a series of genes in the critical 4q region, which is potentially associated with prostate tumor development.     

Activated clotting time (ACT) testing: analysis of reproducibility

Activated Clotting Time (ACT) has been the standard for monitoring heparin anticoagulation in cardiac surgery for three decades. Although a 10% coefficient of variation (CV) is the referenced standard for the test, no recent reports of precision are available. The precision of Hemochron FTCA510 (celite) and KACT (kaolin) ACT test tubes was evaluated using a retrospective analysis of results from both laboratory studies and routine clinical usage. Laboratory studies of reproducibility included analysis of the CV from repetitive testing using multiple lots of ACTs. Substrates used included 40 consecutive lots of control plasma and freshly heparinized donor blood. Across the lots of control plasma, the celite ACT yielded an average CV of 5.4% for the normal control level and 4.0% in the abnormal control level (range 3.6-9.7% and 2.7-6.3%, respectively). The KACT showed similar performance for the normal (mean = 4.5%, range 2.2-7.8%) and abnormal (mean = 3.8%, range 2.0-10.0%). These values, significantly less than 10%, reflect the combined variability of both the ACT tests and the lyophilized, single use vial, control material. Fresh whole blood samples exhibited improved ACT precision when compared to this artificial substrate. CVs for the celite ACT range from 0.6-6.0% at one unit heparin/ml blood to 2.4-11.6% at 5 units/ml where clotting times exceed 650 sec. The KACT showed even lower CVs at all heparin levels, with values of 2.4-7.0%. Clinical evaluations included samples (N = 56) collected from cardiac surgery patients with celite ACT values ranging to 744 sec. Duplicate values differed by an average of 7.5 sec or 1.8%. There was only one clinically significant difference in paired values; a 376 sec paired with a 406 sec, 400 sec being the clinical target time. This retrospective data analysis demonstrates that Hemochron ACT variability is significantly less than 10%.     

The structure of competence in health professions

The past decade has seen widespread research on systematic evaluation of the competence of health professionals. Such activity usually has been carried out in accordance with the prevailing psychological paradigms, in which competence is represented as a trait, or as an intrapsychic factor. However, even when competence has been delimited as problem-solving, the research generally identified a strong situational influence on performance. In this article are assembled a set of diverse but complementary arguments for dispensing with the conventional representations of professional competence. In their place is proposed a relational model in which competence in health professions is seen as the aggregated adaptations of practitioners to the set of special social circumstances that obtain within the situational boundaries of their profession. It is argued that a thorough understanding of the content of professional situations is a necessary prerequisite for successful evaluation of professional competence, since competent behavior is lodged in a network of probabilistic relationships with the surroundings. Also discussed are selected procedural implications of this new model for the conduct of investigations of professional situations.     

Integrating the Accreditation Council for Graduate Medical Education Core competencies into the model of the clinical practice of emergency medicine

In response to public pressure for greater accountability from the medical profession, a transformation is occurring in the approach to medical education and assessment of physician competency. Over the past 5 years, the Accreditation Council for Graduate Medical Education (ACGME) has implemented the Outcomes and General Competencies projects to better ensure that physicians are appropriately trained in the knowledge and skills of their specialties. Concurrently, the American Board of Medical Specialties, including the American Board of Emergency Medicine (ABEM), has embraced the competency concept. The core competencies have been integral in ABEM's development of Emergency Medicine Continuous Certification and the development of the Model of Clinical Practice of Emergency Medicine (Model).¹ ABEM has used the Model as a significant part of its blueprint for the written and oral certification examinations in emergency medicine and is fully supportive of the effort to more fully define and integrate the ACGME core competencies into training emergency medicine specialists.To incorporate these competencies into our specialty, an Emergency Medicine Competency Taskforce (Taskforce) was formed by the Residency Review Committee–Emergency Medicine to determine how these general competencies fit in the Model.¹ This article represents a consensus of the Taskforce with the input of multiple organizations in emergency medicine. It provides a framework for organizations such as the Council of Emergency Medicine Residency Directors (CORD) and the Society for Academic Emergency Medicine to develop a curriculum in emergency medicine and program requirement revisions by the Residency Review Committee–Emergency Medicine. In this report, we describe the approach taken by the Taskforce to integrate the ACGME core competencies into the Model. Ultimately, as competency-based assessment is implemented in emergency medicine training, program directors, governing bodies such as the ACGME, and individual patients can be assured that physicians are competent in emergency medicine.     

Platelet-collagen interaction: inhibition by ristocetin and enhancement by von Willebrand factor-platelet binding

The contribution of von Willebrand factor (vWF)-platelet binding to platelet-collagen interaction was examined in vitro. The binding of vWF to platelets was mediated and regulated by ristocetin. Subthreshold concentrations of ristocetin (less than or equal to 1 mg/mL), insufficient to cause ristocetin-induced platelet aggregation (RIPA), were added to platelet-rich plasma (PRP) prior to the addition of collagen. The collagen-induced platelet aggregation (CIPA) was modified by ristocetin and the degree of alteration was dependent on the ristocetin concentration. Response as a function of ristocetin concentration was designated the Collagen-Platelet Aggregation Response (CoI-PAR). In normal PRP the CoI-PAR was a progressive inhibition followed by decreasing inhibition and then an enhanced response. The enhanced response occurred over a narrow range of ristocetin concentrations (0.8 to 1.0 mg/mL). In the absence of vWF (severe von Willebrand's disease, Type I, vWF less than 1%) the CoI-PAR was a progressive, eventually complete inhibition with no enhanced response (with ristocetin concentrations up to 3.0 mg/mL). With addition of vWF to this PRP an enhanced response was observed at a ristocetin concentration inversely proportional to the vWF level. PRP from a patient with severe Hemophilia A showed a response within the normal range. Subthreshold ristocetin did not cause plasma protein precipitation or platelet release of 3H-serotonin, nor induce micro platelet aggregate formation. Digestion of platelet membrane glycoproteins (GP(s] with chymotrypsin demonstrated that upon removal of GPI, RIPA was absent, CIPA retained and the CoI-PAR was progressive inhibition, with no enhancement. With removal of GPs I, II, and III, RIPA, CIPA, and the CoI-PAR were absent. A dose-response 125I-vWF- platelet binding occurred with increasing ristocetin concentrations which was unchanged by the addition of collagen. These results demonstrated that ristocetin-platelet association inhibited CIPA, and vWF-platelet binding enhanced platelet-collagen adhesion and platelet aggregation. The in vitro-enhanced CIPA represents a vWF-dependent aggregation of sufficient magnitude to overcome the inhibitory effect of ristocetin. These studies demonstrate an influential interaction of ristocetin, vWF, and collagen with the platelet membrane and imply an important hemostatic contribution of vWF-platelet binding in platelet- collagen interaction.     

CADASIL: the dermatologic diagnosis of a neurologic disease. Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an increasingly recognized neurologic disease characterized by pathognomonic changes to the small vessels, particularly in the brain and skin. Although much has recently been written about this disease in the neuropathology literature, to our knowledge nothing has appeared in the dermatology literature. We wish to call attention to the unique role dermatologists and dermatopathologists can play in the diagnosis of this disease. We review the condition's clinical, histologic, and ultrastructural features.     

Optimizing management of hirudin anticoagulation

Accurate anticoagulation monitoring, critical during cardiac surgery (CS), is especially important for novel therapeutics such as hirudins, for which there are no known antidotes. The activated clotting time (ACT), which is standard for heparin monitoring, has been reported to be insufficiently sensitive to high levels of hirudins. A simple, accurate, and sensitive assay is needed to monitor hirudins at the levels required for CS. During the REPLACE/II clinical trials, the HEMOCHRON Jr. Signature ACT+ was used to monitor Angiomax during percutaneous cardiac intervention (PCI) procedures and was observed to lose sensitivity at bivalirudin concentrations greater than 8-10 microg/mL. A new assay, the ACTT, was developed to increase the linear sensitivity of the ACT+ over the range of 15-30 microg/mL bivalirudin to extend the clinical utility of the assay to CS levels. Both in vitro and ex vivo studies were performed using the ACTT and ACT+. In vitro ACT+ and ACTT clotting times, identical for bivalirudin levels up to approximately 5 microg/mL, diverged from each other near 10 microg/mL. The ACTT showed excellent linearity to bivalirudin at concentrations up to 30 microg/ mL. Reproducibility was also superior with coefficients of variation <15% across 13 donors at clotting times <760 seconds. The ACTT was evaluated for monitoring bivalirudin during PCI in 67 patients. The ex vivo comparison of ACTT to ACT+ <340 seconds, showed a slope near 1.0 and an average difference between the tests of 5%. At higher clotting times this slope increased to near 3.0, with an average difference between tests of 20%. These data suggest that the ACTT displays increased sensitivity to high levels of bivalirudin.     

The Hemochron Response RxDx heparin and protamine dosing system

The use of dosing assays to calculate heparin and protamine dose requirements during cardiac surgery has been shown to significantly improve overall postoperative patient outcome. When patients are managed with an individualized dosing system, intraoperative and postoperative transfusion requirements and bleeding are reduced. The Hemochron RxDx system is widely used as a complement to traditional activated clotting time testing to optimize anticoagulation management. The system consists of the heparin response test, the protamine response test, and the protamine dose assay. All are modifications of the activated clotting time using either Celite (Celite Corporation, Santa Barbara, CA) or kaolin as the activator. Dosing is calculated manually using earlier version Hemochron instruments (model 801) or automatically with the Hemochron 8000 or with the early versions of the Hemochron Response and the personal digital assistant (PDA) RxDx calculator. Missing from available user options is an automated RxDx system for the Response. A study was conducted at four clinical sites to compare recently developed Response RxDx software, which eliminates the need for the PDA RxDx calculator, to the existing Hemochron 8000 RxDx and to the Response-PDA RxDx systems. Similar to the current system, the operator inputs the patient's height, weight, and gender, and the software automatically calculates the blood volume. Using the clotting times determined on the Response, bolus heparin and protamine doses and any additional heparin and protamine requirements are calculated automatically. Data were collected from 76 patients, of which, 64 patients were on pump, 11 patients were off pump, and 1 patient was converted from off to on pump. The Response estimated blood volume calculations showed a correlation coefficient of 0.989 when compared with available systems. A good correlation was also observed for the bolus heparin (r = 0.925) and protamine doses (r = 0.900) with equivalence confirmed by a paired student's t test. These data confirm that the Response RxDx system yields results that are identical (P > 0.05) to those obtained using the Hemochron 8000 RxDx or Response-PDA RxDx calculator. The Response RxDx also offers expanded user options related to blood volume limits, expanded clotting time ranges for presetting default values, and flexibility in test sequence. Case records can be printed or downloaded to a PC via the HRDM data management program. The Hemochron Response RxDx represents a complete anticoagulation management system for the cardiac surgical patient.     

Application of bacterial artificial chromosome array-based comparative genomic hybridization and spectral karyotyping to the analysis of glioblastoma multiforme

Identification of genetic losses and gains is valuable in analysis of brain tumors. Locus-by-locus analyses have revealed correlations between prognosis and response to chemotherapy and loss or gain of specific genes and loci. These approaches are labor intensive and do not provide a global view of the genetic changes within the tumor cells. Bacterial artificial chromosome (BAC) arrays, which cover the genome with an average resolution of less than 1 MbP, allow defining the sum total of these genetic changes in a single comparative genomic hybridization (CGH) experiment. These changes are directly overlaid on the human genome sequence, thus providing the extent of the amplification or deletion, reflected by a megabase position, and gene content of the abnormal region. Although this array-based CGH approach (CGHa) seems to detect the extent of the genetic changes in tumors reliably, it has not been robustly tested. We compared genetic changes in four newly derived, early-passage glioma cell lines, using spectral karyotyping (SKY) and CGHa. Chromosome changes seen in cell lines under SKY analysis were also detected with CGHa. In addition, CGHa detected cryptic genetic gains and losses and resolved the nature of subtle marker chromosomes that could not be resolved with SKY, thus providing distinct advantages over previous technologies. There was remarkable general concordance between the CGHa results comparing the cell lines to the original tumor, except that the magnitude of the changes seen in the tumor sample was generally suppressed compared with the cell lines, a consequence of normal cells contaminating the tumor sample. CGHa revealed changes in cell lines that were not present in the original tumors and vice versa, even when analyzed at the earliest passage possible, which highlights the adaptation of the cells to in vitro culture. CGHa proved to be highly accurate and efficient for identifying genetic changes in tumor cells. This approach can accurately identify subtle, novel genetic abnormalities in tumors directly linked to the human genome sequence. CGHa far surpasses the resolution and information provided by conventional metaphase CGH, without relying on in vitro culture of tumors for metaphase spreads.     

Assessment of patient management skills and clinical skills of practising doctors using computer-based case simulations and standardised patients

CONTEXT: Standardised assessments of practising doctors are receiving growing support, but theoretical and logistical issues pose serious obstacles. OBJECTIVES: To obtain reference performance levels from experienced doctors on computer-based case simulation (CCS) and standardised patient-based (SP) methods, and to evaluate the utility of these methods in diagnostic assessment. SETTING AND PARTICIPANTS: The study was carried out at a military tertiary care facility and involved 54 residents and credentialed staff from the emergency medicine, general surgery and internal medicine departments. MAIN OUTCOME MEASURES: Doctors completed 8 CCS and 8 SP cases targeted at doctors entering the profession. Standardised patient performances were compared to archived Year 4 medical student data. RESULTS: While staff doctors and residents performed well on both CCS and SP cases, a wide range of scores was exhibited on all cases. There were no significant differences between the scores of participants from differing specialties or of varying experience. Among participants who completed both CCS and SP testing (n = 44), a moderate positive correlation between CCS and SP checklist scores was observed. There was a negative correlation between doctor experience and SP checklist scores. Whereas the time students spent with SPs varied little with clinical task, doctors appeared to spend more time on communication/counselling cases than on cases involving acute/chronic medical problems. CONCLUSION: Computer-based case simulations and standardised patient-based assessments may be useful as part of a multimodal programme to evaluate practising doctors. Additional study is needed on SP standard setting and scoring methods. Establishing empirical likelihoods for a range of performances on assessments of this character should receive priority.