A needs assessment of education research topics among surgical educators in the United States.

BACKGROUND: There are currently no courses that focus specifically on surgical education research. A needs assessment of surgical educators is required to best design these courses. METHODS: A cross-sectional survey-based study on all faculty members of the Association for Surgical Education was done to determine their education research needs. RESULTS: The overall response rate was 15% and the majority of the 78 respondents were physicians (63%) in their mid- to late career stage (65%). Participants thought research topics should be taught at an advanced level in a workshop format. Senior educators were less interested than junior educators in learning to create conceptual frameworks (p = 0.038) and presenting their research at national meetings (p = 0.014). CONCLUSIONS: Surgical educators desire more training in education research techniques that are taught in a workshop format at a national surgical education meeting. These workshops may lay the groundwork for a nationally recognized certificate in surgical education research.

Improved detection of anterior fibromuscular stroma and transition zone prostate cancer using biparametric and multiparametric MRI with MRI-targeted biopsy and MRI-US fusion guidance.

BACKGROUND: The objective of this study was to analyze the potential of prostate magnetic resonance imaging (MRI) and MRI/transrectal ultrasound-fusion biopsies to detect and to characterize significant prostate cancer (sPC) in the anterior fibromuscular stroma (AFMS) and in the transition zone (TZ) of the prostate and to assess the accuracy of multiparametric MRI (mpMRI) and biparametric MRI (bpMRI) (T2w and diffusion-weighted imaging (DWI)). METHODS: Seven hundred and fifty-five consecutive patients underwent prebiopsy 3 T mpMRI and transperineal biopsy between October 2012 and September 2014. MRI images were analyzed using PIRADS (Prostate Imaging-Reporting and Data System). All patients had systematic biopsies (SBs, median n=24) as reference test and targeted biopsies (TBs) with rigid software registration in case of MRI-suspicious lesions. Detection rates of SBs and TBs were assessed for all PC and sPC patients defined by Gleason score (GS)⩾3+4 and GS⩾4+3. For PC, which were not concordantly detected by TBs and SBs, prostatectomy specimens were assessed. We further compared bpMRI with mpMRI. RESULTS: One hundred and ninety-one patients harbored 194 lesions in AFMS and TZ on mpMRI. Patient-based analysis detected no difference in the detection of all PC for SBs vs TBs in the overall cohort, but in the repeat-biopsy population TBs performed significantly better compared with SBs (P=0.004 for GS⩾3+4 and P=0.022 for GS⩾4+3, respectively). Nine GS⩾4+3 sPCs were overlooked by SBs, whereas TBs missed two sPC in men undergoing primary biopsy. The combination of SBs and TBs provided optimal local staging. Non-inferiority analysis showed no relevant difference of bpMRI to mpMRI in sPC detection. CONCLUSIONS: MRI-targeted biopsies detected significantly more anteriorly located sPC compared with SBs in the repeat-biopsy setting. The more cost-efficient bpMRI was statistically not inferior to mpMRI in sPC detection in TZ/AFMS.

Evolution of sex chromosomes: dosage compensation of the Lcp1-4 gene cluster on the evolving neo-X chromosome in Drosophila miranda.

In Drosophila miranda the small multigene family of the larval cuticle protein (Lcp1-4) genes resides on the evolving neo-X and neo-Y sex chromosome pair while in the sibling species Drosophila pseudoobscura and Drosophila persimilis the gene cluster is inherited autosomally. The neo-Y chromosomal Lcp1, Lcp2 and Lcp4 genes are, as previously shown by us, not expressed and only Lcp3 is expressed at a strongly reduced level. As a first step in understanding the evolutionary mechanism(s) transforming an autosome into a dosage compensated X we analysed the expression behaviour and promoter structure of the Lcp1-4 genes on the neo-X. The normalized relative expression levels reveal that all four neo-X chromosomal Lcp genes in D. miranda males, including Lcp3, are already dosage compensated.

Retroelements: tools for sex chromosome evolution.

Many eukaryotic taxa inherit a heteromorphic sex chromosome pair. It is a generally accepted hypothesis that the sex chromosome pair is derived from a pair of homologous autosomes that has developed after the occurrence of a sex differentiator in an evolutionary process into two structurally and functionally different partners. In most of the analyzed systems the occurrence of the dominant sex differentiator is paralleled by the suppression of recombination within and close by that region. The recombinational isolation can spread in an evolutionary selection process from neighboring regions finally over the whole chromosome. Suppression of recombination strongly biases the distribution of retrotransposons in the genome. Our results and that from others indicate that the major force driving the evolution of Y chromosomes are retrotransposons, remodeling euchromatic chromosome structures into heterochromatic ones. In our model, intact or already eroded retrotransposons become trapped due to their inherent transposition mechanisms in non-recombining regions. The massive accumulation of retrotransposons interferes strongly with the activity of genes. We hypothesize that Y chromosome degeneration is a stepwise evolutionary process: (1) Massive accumulation of retrotransposons occurs in the non-recombining regions. (2) Heterochromatic nucleation centers are formed as a consequence of genomic defense against invasive parasitic elements; the established nucleation centers become epigenetically inherited. (3) Spreading of heterochromatin from the nucleation centers into flanking regions induces in an adaptive process gene silencing of neighbored genes that could either be still intact or in an already eroded condition, e.g., showing point mutations, deletions, insertions; the retroelements should be subjects to the same forces of deterioration as the genes themselves. (4) Constitutive silenced genes are not committed to the same genetic selection pressure as active genes and therefore more exposed to the decay process. (5) Gene dosage balance is reestablished by the parallel evolution of dosage compensation mechanisms. The evolving secondary sex chromosomes, neo-X and neo-Y, of Drosophila miranda are revealed to be a unique and potent model system to catch the evolutionary Y deterioration process in progress.

Enhanced bone apposition to a chemically modified SLA titanium surface.

Increased surface roughness of dental implants has demonstrated greater bone apposition; however, the effect of modifying surface chemistry remains unknown. In the present study, we evaluated bone apposition to a modified sandblasted/acid-etched (modSLA) titanium surface, as compared with a standard SLA surface, during early stages of bone regeneration. Experimental implants were placed in miniature pigs, creating 2 circular bone defects. Test and control implants had the same topography, but differed in surface chemistry. We created the test surface by submerging the implant in an isotonic NaCl solution following acid-etching to avoid contamination with molecules from the atmosphere. Test implants demonstrated a significantly greater mean percentage of bone-implant contact as compared with controls at 2 (49.30 vs. 29.42%; p = 0.017) and 4 wks (81.91 vs. 66.57%; p = 0.011) of healing. At 8 wks, similar results were observed. It is concluded that the modSLA surface promoted enhanced bone apposition during early stages of bone regeneration.

Biased distribution of repetitive elements: a landmark for neo-Y chromosome evolution in Drosophila miranda.

It is generally assumed that the sex chromosomes developed from a pair of homologs. Over evolution, the proto-Y chromosome, with a very short differential segment, matured in its final stage into a heterochromatic and, for the most part, genetically eroded Y chromosome. The constraints on the evolution of the proto-Y chromosome have been speculated upon since the sex chromosomes were discovered. Several models have been suggested. Drosophila miranda has proved to be a unique and potent model system to study Y-chromosome evolution. We use selected test genes distributed along the neo-Y chromosome as entry gates to analyze the molecular mechanisms involved in the process of Y-chromosome evolution. Here, we report our findings on the Krüppel gene (Kr), which is located distally on the neo-sex chromosome pair.

Lymphoscintigraphy in breast cancer: the value of breast lymphoscintigraphy in breast sentinel node staging.

A 28-year-old woman with an infiltrating ductal carcinoma in the upper outer quadrant of the left breast diagnosed by excisional biopsy underwent lumpectomy, intraoperative lymphatic mapping, and sentinel node dissection. This was followed by an immediate completion axillary node dissection using a hand-held gamma probe and isosulfan blue to map the lymphatics. Preoperative breast lymphoscintigraphy showed drainage into the axilla and an apparent area of radiocolloid accumulation in the inferior hemisphere of the left breast. Because our protocol called only for removal of axillary sentinel nodes, the inferior hemisphere radiocolloid accumulation was not removed. The patient did not complete local regional therapy with breast irradiation and developed a mass in the inferior hemisphere of the left breast, which on biopsy was shown to be metastatic breast cancer in an intramammary lymph node. This case illustrates the potential value of breast lymphoscintograms to identify unusual sites of lymphatic drainage that may prove to be clinically relevant.

Stress protection due to plates: myth or reality? A parametric analysis made using the composite beam theory.

A generally accepted idea has been that plate fixation of fractures may result in the structural adaptation of bone (bone loss) to reduced stress (stress protection) with the subsequent danger of refracture after implant removal. This was the negative aspect of stress protection. For this reason, it was proposed that plates made from more deformable materials be used (titanium, polymers or carbon fibres). A theoretical analysis using composite beam theory, with different loading conditions (axial load and bending), demonstrates that stress protection, i.e. early temporary porosis, is a myth. Mechanics of materials shows that when an over-large plate is fixed to small bones (as in small animals, e.g. rabbits), the reduction of bone strain is exaggerated; in contrast, using plates of varying flexibility (steel, titanium or carbon fibre) on large bones leads to strain reduction with an astonishingly similar amplitude.

Sentinel node staging for cutaneous melanoma in a university-affiliated community care setting.

BACKGROUND: The feasibility of intraoperative lymphatic mapping and sentinel lymphadenectomy (SLND) in settings other than high-volume specialized clinics has been questioned. We sought to determine the feasibility of SLND in a university-affiliated private teaching hospital. METHODS: A multidisciplinary sentinel node program was established to include surgeons, nuclear medicine physicians, and pathologists. Within this program, 79 patients with cutaneous melanoma underwent attempted SLND after cutaneous lymphoscintigraphy (CL), between January 1994 and December 1998. All sentinel nodes were examined by hematoxylin-eosin staining and determined whether negative for evidence metastatic disease by both S-100 and HMB 45 immunohistochemical staining. RESULTS: CL was successful in 77 (97%) of 79 patients. A total of 88 lymphatic basins were found to be at risk for metastatic disease by CL. SLND was not successful in the two patients who did not have a successful CL. Sentinel nodes were identified in all but three patients with the remaining 88 lymphatic basins (technical success, 97%). There was one false negative in this group of patients (approximately 1%). CONCLUSIONS: SLND is a highly accurate way of staging the regional node basin. Our technical success rates and false-negative rates indicate the feasibility of this approach in settings other than high-volume specialty clinics.

Common mechanisms of Y chromosome evolution.

Y chromosome evolution is characterized by the expansion of genetic inertness along the Y chromosome and changes in the chromosome structure, especially the tendency of becoming heterochromatic. It is generally assumed that the sex chromosome pair has developed from a pair of homologues. In an evolutionary process the proto-Y-chromosome, with a very short differential segment, develops in its final stage into a completely heterochromatic and to a great extends genetically eroded Y chromosome. The constraints evolving the Y chromosome have been the objects of speculation since the discovery of sex chromosomes. Several models have been suggested. We use the exceptional situation of the neo-Y in Drosophila miranda to analyze the molecular process in progress involved in Y chromosome evolution. We suggest that the first steps in the switch from a euchromatic proto-Y-chromosome into a completely heterochromatic Y chromosome are driven by the accumulation of transposable elements, especially retrotransposons inserted along the evolving nonrecombining part of the Y chromosome. In this evolutionary process trapping and accumulation of retrotransposons on the proto-Y-chromosome should lead to conformational changes that are responsible for successive silencing of euchromatic genes, both intact or already mutated ones and eventually transform functionally euchromatic domains into genetically inert heterochromatin. Accumulation of further mutations, deletions, and duplications followed by the evolution and expansion of tandem repetitive sequence motifs of high copy number (satellite sequences) together with a few vital genes for male fertility will then represent the final state of the degenerated Y chromosome.

The Amylase gene cluster on the evolving sex chromosomes of Drosophila miranda.

On the basis of chromosomal homology, the Amylase gene cluster in Drosophila miranda must be located on the secondary sex chromosome pair, neo-X (X2) and neo-Y, but is autosomally inherited in all other Drosophila species. Genetic evidence indicates no active amylase on the neo-Y chromosome and the X2-chromosomal locus already shows dosage compensation. Several lines of evidence strongly suggest that the Amy gene cluster has been lost already from the evolving neo-Y chromosome. This finding shows that a relatively new neo-Y chromosome can start to lose genes and hence gradually lose homology with the neo-X. The X2-chromosomal Amy1 is intact and Amy2 contains a complete coding sequence, but has a deletion in the 3'-flanking region. Amy3 is structurally eroded and hampered by missing regulatory motifs. Functional analysis of the X2-chromosomal Amy1 and Amy2 regions from D. miranda in transgenic D. melanogaster flies reveals ectopic AMY1 expression. AMY1 shows the same electrophoretic mobility as the single amylase band in D. miranda, while ectopic AMY2 expression is characterized by a different mobility. Therefore, only the Amy1 gene of the resident Amy cluster remains functional and hence Amy1 is the dosage compensated gene.

Enigma of Y chromosome degeneration: neo-Y and neo-X chromosomes of Drosophila miranda a model for sex chromosome evolution.

Y chromosome degeneration is characterized by structural changes in the chromosome architecture and expansion of genetic inertness along the Y chromosome. It is generally assumed that the heteromorphic sex chromosome pair has developed from a pair of homologues. Several models have been suggested. We use the unique situation of the secondary sex chromosome pair, neo-Y and neo-X (X2), in Drosophila miranda to analyze molecular mechanisms involved in the evolutionary processes of Y chromosome degeneration. Due to the fusion of one of the autosomes to the Y chromosome (about 2 Mya), a neo-Y chromosome and a neo-X chromosome, designated X2, were formed. Thus, formerly autosomal genes are inherited now on a pair of sex chromosomes in D. miranda. Analyzing DNA sequences from the X2 and neo-Y region, we observed a massive accumulation of DNA insertions on the neo-Y chromosome. From the analysis of several insertion elements, we present compelling evidence that the first step in Y chromosome degeneration is driven by the accumulation of transposable elements, especially retrotransposons. An enrichment of these elements along an evolving Y chromosome could account for the switch from a euchromatic into a heterochromatic chromatin structure.

The enigma of Y chromosome degeneration: TRAM, a novel retrotransposon is preferentially located on the Neo-Y chromosome of Drosophila miranda.

We have cloned a novel transposable element from the neo-Y chromosome of Drosophila miranda. The size of the element, designated as TRAM, is 3.452 bp, including on both sides long terminal direct repeats (LTRs) of 372 bp, respectively. The element is flanked by a 5-bp target site duplication, ATATG. The putative primer binding site (PBS) for minus-strand priming is complementary to 18 nucleotides of the 3'-end of tRNA(Trp). Data base screens for DNA sequence identities were negative, apart from the sequence motif of the PBS. The deduced amino acid sequence from the large ORF does not reveal identities described for other transposons. In situ hybridizations with TRAM subclones show a biased distribution in the genome, with a massive accumulation of TRAM in the neo-Y chromosome, while the former homologue, the X2 chromosome is devoid of TRAM sites. The enriched occurrence of the TRAM element at the evolving neo-Y chromosome of D.miranda adds compelling evidence in favor of the view that Y chromosome degeneration is driven by the accumulation of transposable elements.

Evolution of the larval cuticle proteins coded by the secondary sex chromosome pair: X2 and neo-Y of Drosophila miranda: I. Comparison at the DNA sequence level.

The larval cuticle protein genes (Lcps) represent a multigene family located at the right arm of the metacentric autosome 2 (2R) in Drosophila melanogaster. Due to a chromosome fusion the Lcp locus of Drosophila miranda is situated on a pair of secondary sex chromosomes, the X2 and neo-Y chromosome. Comparing the DNA sequences from D. miranda and D. melanogaster organization and the gene arrangement of Lcp1-Lcp4 are similar, although the intergene distances vary considerably. The greatest difference between Lcp1 and Lcp2 is due to the occurrence of a pseudogene in D. melanogaster which is not present in D. miranda. Thus the cluster of the four Lcp genes existed already before the separation of the melanogaster and obscura group. Intraspecific homogenizations of different cluster units must have occurred repeatedly between the Lcp1/Lcp2 and Lcp3/Lcp4 sequence types. The most obvious example is exon 2 of the Lcp3 gene in D. miranda, which has been substituted by the corresponding section of the Lcp4 gene rather recently. The homogenization must have occurred before the translocation which generated the neo-Y chromosome. Lcp3 of D. melanogaster has therefore no orthologous partner in D. miranda. Rearrangements in the promoter regions of the D. miranda Lcp genes have generated new, potentially functional CAAT-box motifs. Since three of the Lcp alleles on the neo-Y are not expressed and Lcp3 is expressed only at a reduced level, it is suggestive to speculate that the rearrangements might be involved as cis-regulatory elements in the up-regulation of the X2-chromosomal Lcp alleles, in Drosophila an essential process for dosage compensation. The Lcp genes on the neo-Y chromosome have accumulated more base substitutions than the corresponding alleles on the X2.

Evolution of the larval cuticle proteins coded by the secondary sex chromosome pair: X2 and neo-Y of Drosophila miranda: II. Comparison at the amino acid sequence level.

The larval cuticle proteins (LCPs) are encoded by a multigene family, Lcp1-4, located at the right arm of the metacentric autosome 2 (2R) in Drosophila melanogaster. Due to a chromosome fusion the Lcp locus of Drosophila miranda is situated on a pair of secondary sex chromosomes, the X2 and neo-Y chromosomes. Comparing the deduced amino acid sequences of the autosomal D. melanogaster loci with the sex-chromosomal loci of D. miranda, we were able to trace the evolution of the Lcp loci with respect to their different chromosomal inheritance. The length of the signal peptide is conserved in all four LCPs, while the size of the mature LCPs varies. Conserved protein motifs became obvious from the alignment, indicating regions of structural and functional importance. Analyzing intra- and interspecific sequence similarities of the Lcp gene families allowed us to reconstruct the phylogeny of the gene cluster. Alignment with cuticle amino acid sequences originating from divergent insect species reveals motifs already present in the primordial insect LCPs. These motifs indicate different levels of constraint acting during the evolution of the LCPs.

Evolution of dosage compensation.

In polytene chromosome squashes from the fruit fly Drosophila melanogaster, the single, dosage-compensated X chromosome in males can be distinguished from the autosomes by the presence of an isoform of histone H4 acetylated at lysine 16, H4.Ac16. We have used H4.Ac16 as a marker to examine the evolving relationship between dosage compensation and sex chromosome composition in species of Drosophila with one (D. melanogaster), two (D. pseudoobscura) or three (D. miranda) identifiable X chromosome arms. In each case, we find that H4.Ac16 is distributed as discrete, closely spaced bands along the entire length of each X chromosome, the only exception being the X2 chromosome of D. miranda in which a terminal region constituting about 10% of the chromosome by length is not labelled with anti-H4.Ac16 antibodies. We conclude that, with this exception, dosage compensation extends along the X chromosomes of all three species. As D. pseudoobscura and D. miranda diverged only about 2 Mya, the spread of dosage-compensated loci along X2 has been rapid, suggesting that regional changes rather than piecemeal, gene-by-gene, changes may have been involved.

Endotoxin tolerance is induced in Chinese hamster ovary cell lines expressing human CD14.

Changes in patterns of gene induction by myeloid lineage cells following multiple exposures to endotoxin (lipopolysaccharide; LPS) is a feature of LPS tolerance. To further understand the mechanism of this phenomenon we describe studies using stably transfected Chinese hamster ovary cell lines that express human CD14 (CHO-hCD14). Using NF-kappa B activation as a measure of LPS-induced cell activation we show that a single treatment with LPS renders CHO-hCD14 cells tolerant to subsequent challenge with LPS, but not with other stimuli such as tumor necrosis factor. Tolerance may result from the induction of gene(s) that control LPS-induced signaling pathways and here we suggest that such genes may be found in the group of immediate, early response genes characterized by the protein phosphatase 3CH134. The CHO-hCD14 cell lines provide a novel model system to further explore the mechanism of endotoxin tolerance.

Metal implants and surface reactions.

A metal in living tissue is prone to corrosion. The interaction of the foreign body with the tissue involves the redox reaction (an electron exchange) at the interface, the hydrolysis (a proton exchange) of oxide-hydrates as products of corrosion, and the formation of metal-organic complexes in the electrolyte. Denatured tissue in contact with the foreign body is the consequence. But behaviour of metals is variable; gold, stainless steel and most other metals react as described while few others like titanium and tantalum do not. The absence of a foreign body effect of a chemical kind is, without doubt, favorable in terms of tissue susceptibility to infection in the presence of titanium.

Titanium deposition in regional lymph nodes after insertion of titanium screw implants in maxillofacial region.

The deposition of titanium in regional lymph nodes was studied after insertion of endosseous, plasma-spray-coated titanium screw implants in a total of 19 beagle dogs. Five additional animals with no implants served as the control group. After killing the animals 9 months postoperatively, the regional lymph nodes were carefully excised, and samples were prepared for histologic examination. Other samples were used to identify foreign particles by energy-dispersive x-ray analysis and for measurement of the titanium concentration in the tissue by flameless atomic absorption spectroscopy. Very fine foreign-body particles could be seen in the histologic sections, and they were identified as titanium by energy-dispersive x-ray analysis. The atomic absorption analysis for titanium revealed a significantly higher concentration in the group with implants. The presence of very fine, poorly attached particles on the plasma-sprayed titanium surface suggests that these particles may be mechanically dislodged from the surface on insertion of the implants. This suggests that the fine particles may be transported by phagocytes to the regional lymph nodes, where they could be found without any signs of inflammation or foreign-body reaction.