The diagnostic value of the fibrinogen/fibrin fragment E antigen assay in clinically suspected deep vein thrombosis

We have evaluated the fibrinogen/fibrin fragment E antigen assay as a diagnostic test in patients with clinically suspected venous thrombosis by comparing the results of this assay with venography in 272 patients. The result of the fragment E antigen assay was elevated in 79 of 80 patients with positive venograms for recent venous thrombosis (sensitivity 99%) and within the normal range in 161 of 192 patients with normal venograms (specificity 84%). The fragment E assay was also evaluated in 130 medical and surgical controls without evidence of venous thrombosis by leg scanning and the test was found to be relatively nonspecific. However, in the patient group under study, a correct clinical diagnosis of no thrombosis, based on a normal fragment E result, was made in 161 of 162 cases (negative predictive value of 99%). Therefore, a normal test result effectively excludes a diagnosis of venous thrombosis in clinically symptomatic patients. The assay, as currently performed, is technically demanding and takes 24 hr to complete. Therefore, it will have to be simplified before it can be applied to clinical practice.     

In vivo expression of the B7 costimulatory molecule by subsets of antigen-presenting cells and the malignant cells of Hodgkin's disease

The B-lymphocyte/accessory-cell activation antigen B7 (BB1) has been shown in vitro to stimulate T-lymphocyte proliferation and cytokine production via CD28 present on the latter cells. In this study, benign lymphoid tissues, lymphomas, and extralymphoid inflammatory sites were examined immunohistochemically using anti-B7 and other relevant monoclonal antibodies. B7 was expressed by benign transformed germinal center B cells, as it was by B cells of follicular lymphomas. B7 was also expressed by a subpopulation (a mean of 31% to 65%) of macrophages and dendritic cells in a variety of lymphoid tissues. It was present in abundance on all macrophages constituting sarcoid granulomas in lymph nodes. In extralymphoid inflammation, 17% to 35% of macrophages expressed B7 only weakly. Cases of Hodgkin's disease showed expression of B7 by the majority of Reed-Sternberg cells or malignant mononuclear variants, a phenomenon that potentially contributes to the lymphocytic accumulation that is a feature of this condition. CD28+ T cells were seen in all areas where T cells were present. B7+ and CD28+ cells colocalized in, for example, lymphoid follicles, lymph node paracortex, sarcoid granulomas, and Hodgkin's disease tissue, indicating a potential for cellular interaction via these molecules at these sites.     

The morphology and evolution of chondrichthyan cranial muscles: A digital dissection of the elephantfish Callorhinchus milii and the catshark Scyliorhinus canicula

The anatomy of sharks, rays, and chimaeras (chondrichthyans) is crucial to understanding the evolution of the cranial system in vertebrates due to their position as the sister group to bony fishes (osteichthyans). Strikingly different arrangements of the head in the two constituent chondrichthyan groups—holocephalans and elasmobranchs—have played a pivotal role in the formation of evolutionary hypotheses targeting major cranial structures such as the jaws and pharynx. However, despite the advent of digital dissections as a means of easily visualizing and sharing the results of anatomical studies in three dimensions, information on the musculoskeletal systems of the chondrichthyan head remains largely limited to traditional accounts, many of which are at least a century old. Here, we use synchrotron tomographic data to carry out a digital dissection of a holocephalan and an elasmobranch widely used as model species: the elephantfish, Callorhinchus milii, and the small-spotted catshark, Scyliorhinus canicula. We describe and figure the skeletal anatomy of the head, labial, mandibular, hyoid, and branchial cartilages in both taxa as well as the muscles of the head and pharynx. In Callorhinchus, we make several new observations regarding the branchial musculature, revealing several previously unreported or ambiguously characterized muscles, likely homologous to their counterparts in the elasmobranch pharynx. We also identify a previously unreported structure linking the pharyngohyal of Callorhinchus to the neurocranium. Finally, we review what is known about the evolution of chondrichthyan cranial muscles from their fossil record and discuss the implications for muscle homology and evolution, broadly concluding that the holocephalan pharynx is likely derived from a more elasmobranch-like form which is plesiomorphic for the chondrichthyan crown group. This dataset has great potential as a resource, particularly for researchers using these model species for zoological research, functional morphologists requiring models of musculature and skeletons, as well as for palaeontologists seeking comparative models for extinct taxa.     

FLT4/VEGFR3 and Milroy Disease: Novel Mutations,a Review of Published Variants and Database Update

Milroy disease (MD) is an autosomal dominantly inherited primary lymphedema. In 1998, the gene locus for MD was mapped to 5q35.3 and variants in the VEGFR3 (FLT4) gene, encoding vascular endothelial growth factor receptor 3 (VEGFR3), were identified as being responsible for the majority of MD cases. Several reports have since been published detailing pathogenic FLT4 mutations. To date, a total of 58 different variants in FLT4, 20 of which are unpublished, have been observed in 95 families with MD. A review of published mutations is presented in this update. Furthermore, the unpublished variants are presented including clinical data. Comparison of clinical features in patients and their families with the same mutations reveals incomplete penetrance and variable expression, making genotype–phenotype correlations difficult. Most mutations are missense, but a few deletions and one splicing variant have also been reported. Several animal models have confirmed the role of VEGFR3 in lymphangiogenesis and studies show mutant VEGFR3 receptors are not phosphorylated. Here, an MD patient with the same p.Ile1053Phe change as seen in the Chy mouse is presented for the first time. This finding confirms that this mouse lineage is an excellent model for MD. All the data reviewed here has been submitted to a database based on the Leiden Open (source) Variation Database (LOVD) and is accessible online at www.lovd.nl/flt4.     

Platelets inhibit the induction of nitric oxide synthesis by interleukin-1 beta in vascular smooth muscle cells

We have investigated the role of platelets in regulating the hemostatic and vasomotor properties of vascular smooth muscle. Experiments were performed to examine the effect of the releasate from activated platelets on the production of nitric oxide from interleukin-1 beta (IL- 1 beta)-treated cultured rat aortic smooth muscle cells. Treatment of vascular smooth muscle cells with IL-1 beta resulted in significant accumulation of nitrite in the culture media and in marked elevation of intracellular cyclic guanosine monophosphate (GMP) levels. The releasate from collagen-aggregated platelets blocked the IL-1 beta- mediated production of nitrite and the accumulation of cyclic GMP in smooth muscle cells in a platelet number-dependent manner. In functional assays, the perfusates from columns containing IL-1 beta- treated smooth muscle cells relaxed detector blood vessels without endothelium and the addition of IL-1 beta-treated smooth muscle cells to suspensions of platelets inhibited their thrombin-induced aggregation. The simultaneous treatment of smooth muscle cells with IL- 1 beta and the platelet releasate abolished both the vasorelaxing activities of the perfusates and the inhibition of platelet aggregation. Platelet releasates treated with a neutralizing antibody to platelet-derived growth factor (PDGF) failed to block IL-1 beta- induced nitric oxide production by the smooth muscle cells, as measured by both biochemical and functional assays. The platelet releasate from a patient with gray platelet syndrome likewise failed to block IL-1 beta-induced nitrite release by smooth muscle cells. These results demonstrate that platelets downregulate the production of nitric oxide by IL-1 beta-treated vascular smooth muscle cells through the release of PDGF. This effect may represent a novel mechanism by which platelets regulate vasomotor tone and thrombus formation at sites of vascular injury.     

Thioredoxin-Interacting Protein Deficiency Protects against Diabetic Nephropathy

Expression of thioredoxin-interacting protein (TxNIP), an endogenous inhibitor of the thiol oxidoreductase thioredoxin, is augmented by high glucose (HG) and promotes oxidative stress. We previously reported that TxNIP-deficient mesangial cells showed protection from HG-induced reactive oxygen species, mitogen-activated protein kinase phosphorylation, and collagen expression. Here, we investigated the potential role of TxNIP in the pathogenesis of diabetic nephropathy (DN) in vivo. Wild-type (WT) control, TxNIP^−/−, and TxNIP^+/− mice were rendered equally diabetic with low-dose streptozotocin. In contrast to effects in WT mice, diabetes did not increase albuminuria, proteinuria, serum cystatin C, or serum creatinine levels in TxNIP^−/− mice. Whereas morphometric studies of kidneys revealed a thickened glomerular basement membrane and effaced podocytes in the diabetic WT mice, these changes were absent in the diabetic TxNIP^−/− mice. Immunohistochemical analysis revealed significant increases in the levels of glomerular TGF-β1, collagen IV, and fibrosis only in WT diabetic mice. Additionally, only WT diabetic mice showed significant increases in oxidative stress (nitrotyrosine, urinary 8-hydroxy-2-deoxy-guanosine) and inflammation (IL-1β mRNA, F4/80 immunohistochemistry). Expression levels of Nox4-encoded mRNA and protein increased only in the diabetic WT animals. A significant loss of podocytes, assessed by Wilms’ tumor 1 and nephrin staining and urinary nephrin concentration, was found in diabetic WT but not TxNIP^−/− mice. Furthermore, in cultured human podocytes exposed to HG, TxNIP knockdown with siRNA abolished the increased mitochondrial O₂⁻ generation and apoptosis. These data indicate that TxNIP has a critical role in the progression of DN and may be a promising therapeutic target.     

Selecting the best and brightest: A comparison of residency match processes in the United States and Canada

BACKGROUND:

Selecting candidates for plastic surgery residency training remains a challenge. In the United States, academic measures (United States Medical Licensing Exam Step I scores, medical school class rank and publications) are used as primary criteria for candidate selection for residency. In contrast, Canadian medical education de-emphasizes academic measures by using a pass-fail grading system. As a result, choosing residents from many qualified applicants may pose a challenge for Canadian programs without objective measures of academic success.

METHODS:

A 25-question online survey was distributed to program directors of Canadian plastic surgery residency-training programs. Program directors commented on number of yearly residents and applicants; application sections (ranked in importance using a Likert scale); interview invitation and rank-order list determination; and their satisfaction with the selection process.

RESULTS:

Ten Canadian plastic surgery program directors responded (90.9% response rate). The most important application components determining invitation to interview were letters of reference from a plastic surgeon (mean importance of 5.0 on the Likert scale), clinical electives in plastic surgery (mean 4.6) and electives with their program (mean 4.5). Applicants invited for interview were assessed on the quality of their responses to questions, maturity and personality. The majority of program directors agreed that a clinical elective with their program was important for consideration on their rank-order list. Program directors were neutral on their satisfaction with the selection process.

CONCLUSION:

Canadian plastic surgery residency programs emphasize clinical electives with their program and letters of reference from colleagues when selecting applicants for interviews. In contrast to their American counterparts, Canadian program directors rely on clinical interactions with prospective residents in the absence of objective academic measures.