Increased number of aldosterone-sensitive NTS neurons in Dahl salt-sensitive rats.

Dahl salt-sensitive rats develop severe hypertension during a high-sodium diet, but the basis of their salt-sensitive phenotype is not completely understood. A subset of neurons in the nucleus tractus solitarius (NTS) are uniquely sensitive to the adrenal steroid hormone aldosterone, which is critically involved in sodium homeostasis, due to their expression of the enzyme 11-beta-hydroxysteroid dehydrogenase type 2 (HSD2). The number of HSD2 neurons in the NTS was counted in prehypertensive 7-week-old Dahl salt-sensitive rats and compared with two control strains: Dahl salt-resistant and Sprague-Dawley rats. Dahl salt-sensitive rats had more HSD2 neurons than age-matched Dahl salt-resistant and Sprague-Dawley rats (24% and 21%, respectively). Cell counts were also made in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats; the number of HSD2 neurons in both of these strains was similar to the values obtained for Sprague-Dawley rats. The increased number of HSD2-immunoreactive neurons counted in Dahl salt-sensitive rats suggests that they may have a greater number of aldosterone-sensitive NTS neurons. Alternatively, an increase in HSD2 expression in Dahl salt-sensitive rats could increase the overall immunoreactivity, permitting detection of more of these neurons. In either case, the roughly 20% increase in HSD2 neurons in the NTS of prehypertensive Dahl salt-sensitive rats is a novel factor associated with their salt-sensitive phenotype. These neurons may play a role in regulating sodium appetite, which is abnormally suppressed in Dahl salt-sensitive rats.

Interventional sialendoscopy after sialadenectomy.

OBJECTIVES/HYPOTHESIS: To evaluate the use of diagnostic and interventional sialendoscopy in patients with prior parotidectomy or submandibular gland excision and persistent sialadenitis and/or sialolithiasis. STUDY DESIGN: Retrospective case series. METHODS: Retrospective review of medical records, including demographic data, clinical presentation and exam, radiologic studies, and operative reports. RESULTS: Five patients, who had undergone prior sialadenectomy for sialadenitis and/or sialolithiasis, underwent sialendoscopy for persistent symptoms during the study period. Three patients were female and two were male, with ages ranging from 39 to 63 years (median, 47 years). Three patients had prior parotidectomy, and two had prior submandibular gland excision. The duration of time from sialadenectomy to sialendoscopy was 3.25 months to 6 years (median, 26 months). Four of the five patients had successful interventional sialendoscopy, with resolution of their symptoms. These four patients underwent extraction of stones, one of which was previously unrecognized. In one patient, duct cannulation and subsequent sialendoscopy could not be performed owing to scarring at the Stensen's papilla; the patient's symptoms initially persisted after the attempted procedure with gradual improvement. No complications occurred in any patients. Importantly, no sequelae resulted from endoscopic instrumentation and irrigation of salivary ducts that ended in blind pouches. CONCLUSIONS: Sialendoscopy is a safe and frequently effective intervention for persistent sialolithiasis and sialadenitis after salivary gland excision. LEVEL OF EVIDENCE: 4.

Practical guide to understanding the need for clinical practice guidelines.

With recent changes in the landscape of health care, clinical practice guidelines (CPGs) have proliferated. Attitudes about guidelines differ considerably, forming 2 competing viewpoints with considerable tension between them. Some feel CPGs are unneeded or are efforts to create automated "cookie cutter" medical practice; at best, they are perceived as suggestions that may be altered by experience. Others feel they are mandates that must be followed to the letter. This article attempts to explain how and why we have arrived at this point and to explain the origins of the differing viewpoints. We begin by describing the 2 viewpoints and proceed to define the origin of medicine as a profession and to chronicle the evolution of health insurance, medical education, and scientific methods for evaluating evidence.

Practical guide to understanding multivariable analyses: Part A.

Multivariable analyses are complex statistical methods to evaluate the impact of multiple variables on outcomes of interest. Books have been written on each of these methods detailing the mathematical and statistical objectives and processes. However, we have found very little in the way of brief reports that help the nonstatistically trained physician obtain a basic understanding of multivariable analyses in order to have some understanding of the increasing literature using these methods. This work is organized in 2 parts. This article, Part A, addresses the "big 4" algebraic methods of multivariable analysis. The primary focus of Part A is to present a brief "primer" to help the reader understand the methods and uses; it expressly avoids the many details of statistical assumptions, calculations, and myriad branching alternatives. Part B will concentrate on conjunctive consolidation and will focus on enough information to allow the interested reader to actually perform the analysis. For the statistical scholar, we have included references to several voluminous serious works.

Practical guide to understanding multivariable analyses, Part B: conjunctive consolidation.

Conjunctive consolidation, one method of multivariable analysis by arranging data into clusters, is intuitive and transparent. An unexpected consequence in writing this article was the discovery of just how useful it is in critically analyzing articles and in designing new projects. It has stimulated a fresh understanding as to the value of multivariable thinking in all clinical research. This article is organized into the sequential steps for performing conjunctive consolidation for critically analyzing an article of interest and for completing the process, pending all required data are available. Investigators, particularly those who perform clinical research, should consider conjunctive consolidation as a valuable method of multivariable analysis with which to report data.

Accuracy of computed tomography detection of superior canal dehiscence.

HYPOTHESIS: High-resolution temporal bone computed tomography (CT) may erroneously demonstrate a superior semicircular canal dehiscence (SSCD) where none exists and inaccurately display the size of a dehiscence. BACKGROUND: CT is an integral component of the diagnosis of SSCD. The prevalence of dehiscence as measured on computed tomographic scan is approximately eightfold higher than that on histologic studies, suggesting that CT may have a relatively low specificity for identifying canal dehiscence. This, in turn, can lead to an inappropriate diagnosis and treatment plan. METHODS: We quantified the accuracy of CT in identifying a dehiscence of the superior semicircular canal in a cadaver model using microCT as a gold standard. The superior canals of 11 cadaver heads were blue lined. Twelve of the 22 ears were further drilled to create fenestrations of varying sizes. Heads were imaged using medical CT, followed by microCT scans of the temporal bones at 18-µm resolution. Diagnosis of dehiscence and measurements of dehiscence size were performed on clinical CT and compared with that of microCT. RESULTS: Clinical CT identified 7 of 8 intact canals as dehiscent and tended to overestimate the size of smaller fenestrations, particularly those surrounded by thin bone. CONCLUSION: These findings confirm that medical CT cannot be used as the exclusive gold standard for SSCD and that, particularly for small dehiscences on CT, clinical symptoms must be clearly indicative of a dehiscence before surgical treatment is undertaken. Preoperative counseling for small dehiscences may need to include the possibility that no dehiscence may be found despite radiologic evidence for it.