[Pseudoreplication, chatter, and the international nature of science: a response to D.V. Tatarnikov].

The commentary by Tatarnikov (2005) on the design and analysis of manipulative experiments in ecology represents an obvious danger to readers with poor knowledge of modern statistics due to its erroneous interpretation of pseudoreplication and statistical independence. Here we offer clarification of those concepts--and related ones such as experimental unit and evaluation unit--by reference to studies cited by Tatarnikov (2005). We stress the necessity of learning from the accumulated experience of the international scientific community in order not to repeat the errors found in earlier publications that have already been analyzed and widely written about. (An Englisch translation of the full article is available as a pdf-file from either or the authors.)

Screening parameters for ThinPrep and conventional gynecologic cytology via automated monitoring.

OBJECTIVE: To compare diagnostic discrepancies and screening parameters between conventional (CP) and ThinPrep (TP) (Cytyc Corporation, Boxborough, Massachusetts, U.S.A.) cervicovaginal samples using Pathfinder (Neopath, Redmond, Washington, U.S.A.). STUDY DESIGN: Pathfinder tracked average screening time, percent slide coverage and percent overlap of viewing fields for CP and TP. False negative rate (FNR) was determined by rescreening 10% of random and high-risk negative cases. CP and TP FNR with Pathfinder were compared to control groups without Pathfinder. RESULTS: A total of 46,393 Pathfinder cases were evaluated (43,354 CP, 3,039 TP) as compared to 62,981 without Pathfinder (60,307 CP, 2,674 TP). FNR was calculated for 12,983 negatives. Using Pathfinder resulted in a significant reduction in FNR for CP atypical squamous cells of undetermined significance and atypical glandular cells of undetermined significance cases. No decrease in FNR was observed for CP squamous intraepithelial lesions or for TP cases. TP slides were screened 66 seconds faster on average than CP. With electronic feedback, mean percent slide coverage and percent overlap were similar between CP and TP cases. Without feedback, coverage dropped and overlap increased slightly for both CP and TP. Technologists screened faster with feedback, saving an average of 50 seconds on CP and 41 seconds on TP. CONCLUSION: Pathfinder significantly reduced FNR for CP but not TP. Technologists screened TP significantly faster than CP while maintaining similar coverage and overlap. Pathfinder feedback itself may decrease screening time.

Feasibility of endovascular repair of abdominal aortic aneurysms with local anesthesia with intravenous sedation.

PURPOSE: Local anesthesia has been shown to reduce cardiopulmonary mortality and morbidity rates in patients who undergo selected peripheral vascular procedures. The efforts to treat abdominal aortic aneurysms (AAAs) with endovascular techniques have largely been driven by the desire to reduce the mortality and morbidity rates as compared with those associated with open aneurysm repair. Early results have indicated a modest degree of success in this goal. The purpose of this study was to investigate the feasibility of endovascular repair of AAAs with local anesthesia. METHODS: During a 14-month period, 47 patients underwent endovascular repair of infrarenal AAAs with local anesthesia that was supplemented with intravenous sedation. Anesthetic monitoring was selective on the basis of comorbidities. The patient ages ranged from 48 to 93 years (average age, 74.4 +/- 9.8 years). Of the 47 patients, 55% had significant coronary artery disease, 30% had significant chronic obstructive pulmonary disease, and 13% had diabetes. The average anesthesia grade was 3.1, with 30% of the patients having an average anesthesia grade of 4. The mean aortic aneurysm diameter was 5.77 cm (range, 4.5 to 12.0 cm). All the implanted grafts were bifurcated in design. RESULTS: Endovascular repair of the infrarenal AAA was successful for all 47 patients. One patient required the conversion to general anesthesia to facilitate the repair of an injured external iliac artery via a retroperitoneal approach. The operative mortality rate was 0. No patient had a myocardial infarction or had other cardiopulmonary complications develop in the perioperative period. The average operative time was 170 minutes, and the average blood loss was 623 mL (range, 100 to 2500 mL). The fluid requirements averaged 2491 mL. Of the 47 patients, 46 (98%) tolerated oral intake and were ambulatory within 24 hours of graft implantation. The patients were discharged from the hospital an average of 2.13 days after the procedure, with 87% of the patients discharged less than 48 hours after the graft implantation. Furthermore, at least 30% of the patients could have been discharged on the first postoperative day except for study protocol requirements for computed tomographic scanning at 48 hours. CONCLUSION: This is the first reported series that describes the use of local anesthesia for the endovascular repair of infrarenal AAAs. Our preliminary results indicate that the endovascular treatment of AAAs with local anesthesia is feasible and can be performed safely in a patient population with significant comorbidities. The significant potential advantages include decreased cardiopulmonary morbidity rates, shorter hospital stays, and lower hospital costs. A definitive evaluation of the benefits of local anesthesia will necessitate a direct comparison with other anesthetic techniques.

Long-term patency rates, complications and cost-effectiveness of polytetrafluoroethylene (PTFE) grafts for hemodialysis access: a prospective study that compares Impra versus Gore-tex grafts.

Manufacturers of polytetraflouroethylene (PTFE) grafts used for chronic hemodialysis access describe specific advantages for their respective grafts, which presumably result in greater graft patency rates, reduced complications and decreased overall costs. There are few data available in the literature to support or contradict these alleged benefits. Therefore, this prospective study was undertaken to evaluate and compare patency rates, complications and costs between two of the leading brands of PTFE that are currently being marketed for use as hemodialysis access grafts. Totals of 190 primary PTFE grafts (100 Gore-tex (W. L. Gore and Associates, Flagstaff, AZ) and 90 Impra (C. R. Bard Inc., Tempe, AZ)) were implanted in 168 consecutive patients with end-stage renal disease. A policy of non-interventions was employed for patent grafts, as no attempt was made to assist primary patency. Grafts that occluded during follow-up underwent secondary revision to maintain patency. There was no difference in primary and secondary patency by life-table analysis between Gore-tex and Impra grafts at 2 years (P > 0.53 and P > 0.13, respectively). There was also no significant difference between Gore-tex and Impra in the number of days before the first thrombectomy or in the number of thrombectomies or revisions per graft (P > O.50). Likewise, the incidence of complications was similar between the two grafts. The cost of graft implantation and maintenance of patency was not significantly different between Gore-tex and Impra grafts. It is concluded that either graft can be used for hemodialysis access with similar expected outcomes for at least 2 years following implantation.

Primary subclavian-axillary vein thrombosis: consensus and commentary.

Fifteen multiple-choice questions concerning options in the management of primary subclavian-axillary vein thrombosis were discussed by a panel of experts and then voted upon by 25 attending vascular surgeons with a special interest in venous disease and considerable experience in subclavian-axillary vein thrombosis. The large majority favored, or agreed upon: (1) early clot removal for active, healthy patients with a need/desire to use the involved limb in work or sport; (2) catheter-directed thrombolysis as initial therapy; (3) further therapy based on follow-up positional venography; (4) surgical relief of demonstrated thoracic outlet compression after a brief period of anticoagulant therapy; (5) conservative therapy if post-lysis venogram showed either (a) no extrinsic compression or (b) a short residual occlusion; and (6) intervention for residual intrinsic lesions with over 50% narrowing. However, there was little unanimity regarding the most appropriate intervention for residual stenoses, with opinion split between surgical and percutaneous transluminal angioplasty. For residual symptomatic occlusion 66% favored jugular vein turndown; only 10% would perform first rib removal.

Carotid artery disease in women.

Our understanding of cerebrovascular disease in women is hampered by a paucity of studies that include adequate numbers of female patients. Most studies are heavily biased toward men. Although women have fewer strokes than men and have a better long-term prognosis after strokes or TIAs, cerebrovascular disease still affects large numbers of women. Presently, there is little convincing evidence that standard medical therapy with aspirin for prevention of strokes in women is of benefit. Perhaps, inclusion of insufficient numbers of women in the aspirin trials for symptomatic carotid stenoses explains the apparent lack of therapeutic efficacy. Although ticlopidine does not appear particularly promising for prevention of stroke, other novel antiplatelet and antithrombotic agents are being developed and need to be tested in women. Carotid endarterectomy prevents strokes in women and men, but women enjoy a lesser benefit; this appears to be true both for symptomatic and asymptomatic carotid stenoses. Whereas restenosis is more common in women than men, most lesions remain asymptomatic. Surgery will probably remain the mainstay of treatment for cerebrovascular disease in women and men, but in this era of "gender correctness," the striking absence of reliable data exclusively applicable to women confirms the need for additional studies.

Effects of dietary protein source on Basenjis with immunoproliferative enteropathy.

The effects of 3 experimental diets that varied only in the source of dietary protein (ie, poultry, cereal, red meat) were compared in Basenjis (n = 8) with immunoproliferative enteropathy and healthy Beagles (n = 8). Significant differences in fecal character, serum IgA concentration, and intestinal digestive and absorptive function were not induced by the different sources of dietary protein. The results of this study do not support a causal role for dietary protein source in the pathogenesis of immunoproliferative enteropathy of Basenjis.

Gastric acid secretion in Basenji dogs with immunoproliferative enteropathy.

Gastric acid secretion was studied in 13 Basenji dogs with immunoproliferative enteropathy. Considerable variation in the severity of gastritis and enteritis existed among dogs. Basenji dogs were categorized into two groups on the basis of postmortem gastric and intestinal histology (group I, gastritis and enteritis; group II, only enteritis). Pentagastrin-induced gastric acid secretory capacity was increased (P less than 0.002) in group II dogs as compared to healthy Beagle controls. Gastric acid secretory capacity of Basenji dogs with gastritis and enteritis (group I) was not different from that observed in control dogs. Basal serum gastrin concentrations and secretin-stimulated serum gastrin concentrations of either group of Basenji dogs did not differ from controls. On the basis of symptomatology, Basenji dogs with diarrhea had significantly increased basal and postsecretin stimulation gastrin concentrations (P = 0.01) when compared with asymptomatic Basenji or healthy control dogs. These findings support a potential role for altered gastric acid secretory capacity in the pathogenesis of immunoproliferative enteropathy of Basenji dogs. Results of the secretin stimulation studies support previous pathologic studies that failed to detect gastrin-secreting tumors. Incorporated into this investigation was a trial to determine whether the combination of oxymorphone and acepromazine could be used for acid secretory studies. Compared to pentobarbital, which has been frequently used for acid secretory studies in a research setting, the drug combination resulted in increased gastric fluid volumes, a comparative increase in acid secretion, and a rapid uneventful recovery. We conclude that the combination of oxymorphone and acepromazine provides an acceptable means of restraint in dogs undergoing acid secretory studies.