Restricted dispersal in a sea of gene flow.

How far do marine larvae disperse in the ocean? Decades of population genetic studies have revealed generally low levels of genetic structure at large spatial scales (hundreds of kilometres). Yet this result, typically based on discrete sampling designs, does not necessarily imply extensive dispersal. Here, we adopt a continuous sampling strategy along 950 km of coast in the northwestern Mediterranean Sea to address this question in four species. In line with expectations, we observe weak genetic structure at a large spatial scale. Nevertheless, our continuous sampling strategy uncovers a pattern of isolation by distance at small spatial scales (few tens of kilometres) in two species. Individual-based simulations indicate that this signal is an expected signature of restricted dispersal. At the other extreme of the connectivity spectrum, two pairs of individuals that are closely related genetically were found more than 290 km apart, indicating long-distance dispersal. Such a combination of restricted dispersal with rare long-distance dispersal events is supported by a high-resolution biophysical model of larval dispersal in the study area, and we posit that it may be common in marine species. Our results bridge population genetic studies with direct dispersal studies and have implications for the design of marine reserve networks.

Rapid mineralocorticoid receptor trafficking.

The mineralocorticoid receptor (MR) is a ligand-dependent transcription factor that physiologically regulates water-electrolyte homeostasis and controls blood pressure. The MR can also elicit inflammatory and remodeling processes in the cardiovascular system and the kidneys, which require the presence of additional pathological factors like for example nitrosative stress. However, the underlying molecular mechanism(s) for pathophysiological MR effects remain(s) elusive. The inactive MR is located in the cytosol associated with chaperone molecules including HSP90. After ligand binding, the MR monomer rapidly translocates into the nucleus while still being associated to HSP90 and after dissociation from HSP90 binds to hormone-response-elements called glucocorticoid response elements (GREs) as a dimer. There are indications that rapid MR trafficking is modulated in the presence of high salt, oxidative or nitrosative stress, hypothetically by induction or posttranslational modifications. Additionally, glucocorticoids and the enzyme 11beta hydroxysteroid dehydrogenase may also influence MR activation. Because MR trafficking and its modulation by micro-milieu factors influence MR cellular localization, it is not only relevant for genomic but also for nongenomic MR effects.

Perioperative application of L-alanyl-L-glutamine in cardiac surgery: effect on the polarized T cell cytokine expression.

At risk patients undergoing cardiac surgery with cardiopulmonary bypass have increased rates of postoperative infectious morbidity. Postoperatively, after cardiac surgery, an immunosuppression in the form of a polarization of T helper (Th) cells with a decreased Th1 response (IL-2 and IFN-gamma) and an increased Th2 response (IL-4 and IL-10) is recognized. Therapeutic strategies to modulate the immunological response include special key nutrients such as the amino acid glutamine favoring the Th2 response. There is no information available concerning its effect in patients undergoing cardiac surgery. The aim of this clinical study was to evaluate the effects of a perioperative infusion of glutamine on the polarized lymphocyte T cell cytokine expression and on infectious morbidity in cardiac surgery patients at risk of infection. Seventy-eight patients were included in the study undergoing elective cardiac surgery with a lymphopenia less than 1.2 giga/l. One or more of the following criteria had to be met: age older than 70 years, ejection fraction less than 40%, or mitral valve replacement. We randomly assigned patients to receive infusions of either high-dose L-alanyl-L-glutamine dipeptide [0.5 g/(kg day) glutamine] dissolved in an amino acid solution or an isonitrogeneous, isocaloric, isovolemic nutritional solution. An additional group with normal saline served as control to eliminate any nonspecific nutritional effect. We started the infusion after induction of anesthesia with 1,000 ml/24 h and continued it for 3 days. The primary endpoint was intracellular T cell cytokine expression (including the description in tertiles) on the first postoperative day (pod 1). Secondary endpoints were postoperative infection rate, mortality rate, cardiovascular circulation ventilation time, and renal function. A high-dose perioperative glutamine application leading to mean plasma levels of 1,177 microM had only a minor influence on the polarized intracellular T cell cytokine expression. On pod 1 there was a polarization of T cells, i.e., an augmented Th2 response with an increased number of IL-6 and IL-10 producing cells. On the other side the Th1 response with IL-2 and TNF-alpha declined on pods 1 and 2. Only the intracellular IL-2 response in the lower tertile of IL-2 production was improved with glutamine indicating a small influence. We did not observe any effects on the numbers of postoperative infections; on mortality rate; on cardiovascular circulation; on ventilation time or on renal function. The elevation of glutamine plasma levels by a perioperative intravenous infusion of L-alanyl-L-glutamine influenced the intracellular expression of IL-2 in the lower tertile only slightly. However, mean glutamine values in the other groups remained above or close 500 microM, thus suggesting that glutamine supply to the immune cells was still adequate in most patients, and that glutamine deficiency, if it occurred, was marginal. In the event of a severe glutamine deficiency the observed effect on cytokine production could be more pronounced. Furthermore, we could not observe any obvious clinical advantage in this at risk cardiac surgical patient population. A glutamine supplementation for patients undergoing cardiac surgery without a clear glutamine deficiency is not recommended.

Results of and comments on the 1998 survey of the American Association of Academic Chief Residents in Radiology.

RATIONALE AND OBJECTIVES: The American Association of Academic Chief Residents in Radiology annually surveys residency programs on a variety of issues related to residency training. The survey allows for comparison between programs regarding training and follows trends on current issues. MATERIALS AND METHODS: Questionnaires were mailed to all accredited programs in the United States (188 programs). The questionnaire consisted of questions regarding general demographic information and specific topics regarding residency training. The 1998 survey focused on turf issues, teleradiology use, residency selection, and prior training. RESULTS: Completed surveys from 61 programs (32.4%) were returned. Important findings included (a) the ongoing turf battles regarding vascular and obstetric-gynecologic ultrasound, both in general hospital and emergency department patients, (b) the use of teleradiology by most residents, and (c) the low percentage of women in radiology residency programs. CONCLUSION: The information obtained during yearly surveys is useful for program evaluation and future planning. Current survey results indicate an increasing use of teleradiology in residency over the past 4 years. The turf battles in ultrasonography (both vascular and obstetric) have remained unchanged over the same time frame.

A cost minimization approach to the diagnosis of skeletal neoplasms.

OBJECTIVE: Percutaneous needle aspiration (PNA) has been widely used to diagnose bone malignancies. Successful aspirates hinge on the ability of the operator to obtain an adequate or diagnostic sample, and a skilled cytologist to make a diagnosis on needle aspirates. False-negative aspirates could pose a serious problem. This study is designed to evaluate the cost-effectiveness of PNA in the diagnosis of skeletal neoplasms using a cost minimization approach. DESIGN: All PNA performed over a 44-month period were reviewed retrospectively. Ninety-four skeletal biopsies were performed to diagnose a clinically or roentgenographically suspicious lesion: 69 for a suspected metastatic malignancy, and 25 for a suspected primary malignancy. The PNA results were collected and reviewed, sensitivities and specificities were determined (compared with open biopsy results or clinical follow-up as the gold standards), and the probabilities were applied to a decision tree. Charges were obtained from the patient's billing and converted into costs by a cost-charge ratio. Sensitivity analysis was performed to determine the costs of each branch of the decision tree, and ultimately the final cost of the two strategies: (1) PNA for all suspected neoplasms followed by open biopsy for negative and non-diagnostic PNA results, or (2) open biopsy for all suspected neoplasms. RESULTS: In diagnosing a suspected metastatic skeletal neoplasm, PNA had a sensitivity of 88%, a specificity of 100%, and a non-diagnostic result in 3% of cases. Cost analysis determined a savings of $ US 2486 per patient when "PNA strategy" was used instead of "open biopsy strategy". In diagnosing a suspected primary neoplasm, PNA hat a sensitivity 75%, a specificity of 100%, and a non-diagnostic result in 16% of cases. Cost analysis determined a savings of $ US 954 per patient when "PNA strategy" was used instead of "open biopsy strategy". By using "PNA strategy" instead of "open biopsy strategy" at this institution we would have saved $ US 195384 over the 44-month period. CONCLUSIONS: Metastatic skeletal neoplasms could be reliably diagnosed by PNA, and followed by open biopsy if the PNA result is negative or non-diagnostic, at a significant cost saving over open biopsy. Diagnosing primary skeletal neoplasms using "PNA strategy" offers a slight cost saving compared with "open biopsy strategy", but too few primary skeletal neoplasms were evaluated to recommend the best diagnostic approach.

Rapid detection of respiratory viruses by shell vial culture and direct staining by using pooled and individual monoclonal antibodies.

The Bartels respiratory virus panel detection kit is an indirect fluorescent-antibody (IFA) method that uses pooled and individual antisera for tissue culture confirmation of seven respiratory viruses. We evaluated these reagents for detecting viral antigen in shell vial cultures and by direct staining of cells from respiratory specimens. The isolation from 254 specimens of respiratory viruses in shell vial cultures compared with standard tube cultures was highly sensitive (94%) and specific (97.3%). The numbers of viral isolates detected in three consecutive years of testing with shell vial cultures were 68 of 254 (26.8%), 101 of 381 (26.5%), and 122 of 430 (28.4%). IFA direct staining of all 1,065 specimens resulted in 183 (17.2) being uninterpretable because of inadequate numbers of cells or interfering fluorescence. The sensitivity and specificity of the interpretable IFA direct stains in comparison with shell vial cultures were 85.9 and 87.1%, respectively. For detection of 881 adequate specimens, Bartels respiratory syncytial virus IFA direct staining compared with an Ortho Diagnostics Systems direct fluorescent-antibody test for respiratory syncytial virus RSV was highly sensitive (95.5%) and specific (97%). Shell vial cultures combined with Bartels IFA reagents are a rapid alternative to standard tube cultures. Bartels IFA direct staining with individual antisera provides useful same-day screening of respiratory specimens, but the antiserum pool was not effective in screening for positive specimens because of excessive amounts of nonspecific fluorescence.