Neoadjuvant chemoradiotherapy for adenocarcinoma of the pancreas: analysis of histopathology and outcome

To examine the histopathologic effect of neoadjuvant therapy and its impact on survival in patients with carcinoma of the pancreas, we retrospectively reviewed the records of 116 patients who underwent resections for pancreatic cancer from 1987 to 2000. Median follow-up of surviving patients was 19 mo(range 4-150 mo). Preoperative chemotherapy was administered in 61 patients (53%) and consisted of 5-fluorouracil/mitomycin C in 35 patients and gemcitabine in 26 patients, given concurrently with external beam radiation (5040 cGy). All resections were performed with curative intent (98 Whipples, 11 total, 6 distal, and 1 central pancreatectomy). Histopathologic examination included an estimation of the amount of fibrosis present in the tumor specimen (expressed as the percentage of fibrosis identified relative to the amount of neoplastic cells present). The mean fibrosis level for the series was 56% (range 5% to 100%). The administration of neoadjuvant therapy resulted in greater fibrosis (73%) than no preoperative treatment (38%) (p = 0.0001). Higher mean fibrosis levels were observed in patients with negative lymph nodes (p = 0.0006) and negative margins (p = 0.05). Factors associated with improved survival(log rank test) included: negative margins (p = 0.001), negative lymph nodes (p = 0.03), and use of neoadjuvant therapy (p = 0.03). Median survival in the neoadjuvant group was 23 mo vs 16 mo without preoperative therapy (p = 0.03). In conclusion, the use of neoadjuvant therapy resulted in a greater degree of fibrosis in the specimen. Patients with negative margins and negative lymph nodes had a greater amount of fibrosis present, and these were significant predictors of improved outcome. Although retrospective,this series suggests an improvement in survival in patients treated with neoadjuvant therapy.     

A modified prenatal growth assessment score for the evaluation of fetal growth in the third trimester using single and composite biometric parameters

Objective: To define modified Prenatal Growth Assessment Scores (mPGAS) for single and composite biometric parameters and determine their reference ranges in normal fetuses.

Methods: Nine anatomical parameters (ap) were measured and the weight estimated (EWT_a, EWT_b) in a longitudinal study of 119 fetuses with normal neonatal growth outcomes. Expected third trimester size trajectories, obtained from second trimester Rossavik size models, were used in calculating Percent Deviations (% Dev's) and their age-specific reference ranges in each fetus. The components of individual % Dev's values outside their reference ranges, designated +iapPGAS, -iapPGAS, were averaged to give +apPGAS and ?apPGAS values for the 3rd trimester. The +iapPGAS and ?iapPGAS values for different combinations of ap (c1a (HC, AC, FDL, ThC, EWT_a), c1b (HC, AC, FDL, ThC, EWT_b), c2 (ThC, ArmC, AVol, TVol), c3 (HC, AC, FDL, EWT_a)) were then averaged to give +icPGAS and ?icPGAS values at different time points or at the end of the third trimester (+cPGAS, ?cPGAS). Values for iapPGAS, ic1bPGAS, and ic2PGAS were compared to their respective apPGAS or cPGAS reference ranges.

Results: All mPGAS values had one 95% range boundary at 0.0%. Upper boundaries of 1D +apPGAS values ranged from 0.0% (HC) to +0.49% (ThC) and were +0.06%, +2.3% and +1.8% for EWT, AVol and TVol, respectively. Comparable values for ?apPGAS were 0.0% (BPD, FDL, HDL), to ?0.58% (ArmC), ?0.13% (EWT), ?0.8% (AVol), and 0.0% (TVol). The +cPGAS, 95% reference range upper boundaries varied from +0.36% (c1b) to +0.89% (c2). Comparable values for ?cPGAS lower boundaries were ?0.17% (c1b) to ?0.43% (c2).

Conclusions: The original PGAS concept has now been extended to individual biometric parameters and their combinations. With the standards provided, mPGAS values can now be tested to see if detection of different types of third trimester growth problems is improved.     

Fetal growth cessation in late pregnancy: its impact on predicted size parameters used to classify small for gestational age neonates

Objective: To evaluate the impact of late 3rd trimester fetal growth cessation on anatomical birth characteristic predictions used in classifying SGA neonates.

Methods: A prospective longitudinal study was performed in 119 pregnancies with normal neonatal growth outcomes. Seven biometric parameters were measured at 3–4 weeks intervals using 3D ultrasonography. Rossavik size models were determined to predict birth characteristics at different ages. Percent Differences (% Diff) were calculated from predicted and measured birth characteristics. Growth Cessation Ages (GCA) were identified when no systematic change in % Diff values occurred after specified prediction ages. Systematic and random prediction errors were compared using different assumptions about the GCA. Predicted and measured size parameters were used to determine six new Growth Potential Realization Index (GPRI) reference ranges. Five were used to sub-classify 34 SGA neonates (weight?<?10th percentile) based on the number of abnormal GPRI values.

Results: Growth cessation ages were 38 weeks for HC, AC, mid-thigh circumference, estimated weight and mid-arm circumference. Crown-heel length GCA was 38.5 weeks. At GCA, birth characteristics had prediction errors that varied from 0.08?±?3.4% to 15.7?±?9.1% and zero % Diff slopes after 38 weeks. Assuming growth to delivery gave increased systematic and random prediction errors as well as positive % Diff slopes after 38 weeks, MA. Seventeen of the SGA neonates had 0 or 1 abnormal GPRI values [Subgroup 1] and 17 others had 2 or more abnormal values [Subgroup 2]. In Subgroup 1, 4/85 (4.7%) of GPRI's were abnormal while in Subgroup 2, 43/85 (50.6%) were abnormal. Use of only one type of GPRI for SGA subclassification resulted in substantial false negative and some false positive rates when compared to subclassification based on all five GPRI values.

Conclusions: Growth cessation occurred at approximately 38 weeks for all six birth characteristics studied. SGA neonates can be separated into normal and growth restricted subgroups based on the frequency of abnormal GPRI values (GPRI Profile Classification).     

Bacterial genome reduction using the progressive clustering of deletions via yeast sexual cycling

The availability of genetically tractable organisms with simple genomes is critical for the rapid, systems-level understanding of basic biological processes. Mycoplasma bacteria, with the smallest known genomes among free-living cellular organisms, are ideal models for this purpose, but the natural versions of these cells have genome complexities still too great to offer a comprehensive view of a fundamental life form. Here we describe an efficient method for reducing genomes from these organisms by identifying individually deletable regions using transposon mutagenesis and progressively clustering deleted genomic segments using meiotic recombination between the bacterial genomes harbored in yeast. Mycoplasmal genomes subjected to this process and transplanted into recipient cells yielded two mycoplasma strains. The first simultaneously lacked eight singly deletable regions of the genome, representing a total of 91 genes and ∼10% of the original genome. The second strain lacked seven of the eight regions, representing 84 genes. Growth assay data revealed an absence of genetic interactions among the 91 genes under tested conditions. Despite predicted effects of the deletions on sugar metabolism and the proteome, growth rates were unaffected by the gene deletions in the seven-deletion strain. These results support the feasibility of using single-gene disruption data to design and construct viable genomes lacking multiple genes, paving the way toward genome minimization. The progressive clustering method is expected to be effective for the reorganization of any mega-sized DNA molecules cloned in yeast, facilitating the construction of designer genomes in microbes as well as genomic fragments for genetic engineering of higher eukaryotes.Complexities of natural biological systems make it difficult to understand and define precisely the roles of individual genes and their integrated functions. The use of model organisms with a relatively small number of genes enables the isolation of core biological processes from their complex regulatory networks for extensive characterization. However, even the simplest natural microbes contain many genes of unknown function, as well as genes that can be singly or simultaneously deleted without any noticeable effect on growth rate in a laboratory setting (Hutchison et al. 1999; Glass et al. 2006; Posfai et al. 2006). Ill-defined genes and those mediating functional redundancies both compound the challenge of understanding even the simplest life forms.Toward generating a minimal cell where every gene is essential for the axenic viability of the organism, we are pursuing strategies to reduce the 1-Mb genome of Mycoplasma mycoides JCVI-syn1.0 (Gibson et al. 2010). Because we can (1) introduce this genome into yeast and maintain it as a plasmid (Benders et al. 2010; Karas et al. 2013a); and (2) “transplant” the genome from yeast into mycoplasma recipient cells (Lartigue et al. 2009), genetic tools in yeast are available for reducing this bacterial genome. Several systems offer advanced tools for bacterial genome engineering. Here we further exploit distinctive features of yeast for this purpose.Methods for serially replacing genomic regions with selectable markers are limited by the number of available markers. One effective approach is to reuse the same marker after precise and scarless marker excision (Storici et al. 2001). We have previously used a self-excising marker (Noskov et al. 2010) six times in yeast to generate a JCVI-syn1.0 genome lacking all six restriction systems (JCVI-syn1.0 ∆1-6) (Karas et al. 2013a). Despite the advantages of scarless engineering, sequential procedures are time-consuming. When applied to poorly characterized genes with the potential to interact with other genes, some paths for multigene knockout may lead to dead ends that result from synergistic mutant phenotypes. When a dead end is reached, sequentially returning to a previous genome in an effort to find a detour to a viable higher-order multimutant may be prohibitively time-consuming.An alternative approach to multigene engineering, available in yeast, is to prepare a set of single mutants and combine the deletions into a single strain via cycles of mating and meiotic recombination (Fig. 1A; Pinel et al. 2011; Suzuki et al. 2011, 2012). With a green fluorescent protein (GFP) reporter gene inserted in each deletion locus, the enrichment of higher-order yeast deletion strains in the meiotic population can be accomplished using flow cytometry. Here we apply this method to the JCVI-syn1.0 ∆1-6 exogenous, bacterial genome harbored in yeast to nonsequentially assemble deletions for genes predicted to be individually deletable based on biological knowledge or transposon-mediated disruption data. The functional identification of simultaneously deletable regions is expected to accelerate the effort to construct a minimal genome.Open in a separate windowFigure 1.Progressive clustering of deleted genomic segments. (A) Scheme of the method. Light blue oval represents a bacterial cell. Black ring or horizontal line denotes a bacterial genome, with the orange box indicating the yeast vector used as a site for linearization and recircularization. Gray shape denotes a yeast cell. Green dot in the genome indicates a deletion replaced with a GFP marker. (B) Map of deleted regions. Orange box indicates the yeast vector sequence used for genome linearization and recircularization. Green boxes indicate regions deleted in multimutant mycoplasma strains. Blue boxes denote restriction modification (RM) systems that are also deleted in the strains. (C) Pulsed-gel electrophoresis result for deleted genomes. The starting strain was the JCVI-syn1.0 ∆1–6 strain (1062 kb). Two strains were analyzed for each design of simultaneous deletion (962 kb for eight-deletion or 974 kb for seven-deletion genome). Ladder is a set of yeast chromosomes (New England BioLabs). (D) GFP-RFP ratio sorting result. Standard sorting was compared with sorting based on a GFP-RFP ratio (Methods).     

Medical cannabis: A forward vision for the clinician

Medical cannabis has entered mainstream medicine and is here to stay. Propelled by public advocacy, the media and mostly anecdote rather than sound scientific study, patients worldwide are exploring marijuana use for a vast array of medical conditions including management of chronic pain. Contrary to the usual path of drug approval, medical cannabis has bypassed traditional evidence‐based study and has been legalized as a therapeutic product by legislative bodies in various countries. While there is a wealth of basic science and preclinical studies demonstrating effects of cannabinoids in neurobiological systems, especially those pertaining to pain and inflammation, clinical study remains limited. Cannabinoids may hold promise for relief of symptoms in a vast array of conditions, but with many questions as yet unanswered. Rigorous study is needed to examine the true evidence for benefits and risks for various conditions and in various patient populations, the specific molecular effects, ideal methods of administration, and interaction with other medications and substances. In the context of prevalent use, there is an urgency to gather pertinent clinical information about the therapeutic effects as well as risks. Even with considerable uncertainties, the health care community must adhere to the guiding principle of clinical care ‘primum non nocere’ and continue to provide empathetic patient care while exercising prudence and caution. The health care community must strongly advocate for sound scientific evidence regarding cannabis as a therapy.

Significance

Legalization of medical cannabis has bypassed usual drug regulatory procedures in jurisdictions worldwide. Pending sound evidence for effect in many conditions, physicians must continue to provide competent empathetic care with attention to harm reduction. A vision to navigate the current challenges of medical cannabis is outlined.     

Disparities in Weight and Weight Behaviors by Sexual Orientation in College Students

Objectives. We assessed disparities in weight and weight-related behaviors among college students by sexual orientation and gender.Methods. We performed cross-sectional analyses of pooled annual data (2007–2011; n = 33 907) from students participating in a Minnesota state-based survey of 40 two- and four-year colleges and universities. Sexual orientation included heterosexual, gay or lesbian, bisexual, unsure, and discordant heterosexual (heterosexuals engaging in same-sex sexual experiences). Dependent variables included weight status (derived from self-reported weight and height), diet (fruits, vegetables, soda, fast food, restaurant meals, breakfast), physical activity, screen time, unhealthy weight control, and body satisfaction.Results. Bisexual and lesbian women were more likely to be obese than heterosexual and discordant heterosexual women. Bisexual women were at high risk for unhealthy weight, diet, physical activity, and weight control behaviors. Gay and bisexual men exhibited poor activity patterns, though gay men consumed significantly less regular soda (and significantly more diet soda) than heterosexual men.Conclusions. We observed disparities in weight-, diet-, and physical activity–related factors across sexual orientation among college youths. Additional research is needed to better understand these disparities and the most appropriate intervention strategies to address them.In 2011, the Institute of Medicine highlighted the significant lack of research on the health of lesbian, gay, and bisexual (LGB) groups.1 Research has indicated that LGB adults experience worse health outcomes than their heterosexual peers.2–11 These disparities may be attributable to an array of factors, including stigmatization, stress, and limited access to and use of health services.1,12,13 Specific areas of potential disparities among LGB groups lacking substantial research evidence include obesity, diet, physical activity patterns, unhealthy weight control behaviors, and body image. With two thirds of US adults now overweight or obese,14 obesity prevention is a national health priority. Findings from studies examining adult weight disparities by sexual orientation have consistently indicated that lesbian women are more likely to be overweight than heterosexual women.2,11,15–19 Several recent population-based studies have suggested that gay men may be less likely to be overweight than heterosexual men,2,18,20 and additional studies have highlighted concerns regarding body image and unhealthy weight control behaviors among gay men.21–24 Disparities in other behaviors, such as dietary intake and physical activity patterns, have not been studied extensively using population-based samples and, when studied, have yielded inconsistent findings.11,25,26Furthermore, much of the work in this area to date has not focused on the college years. Because nearly half of US high school graduates up to age 24 years are enrolled in postsecondary education,27 colleges and universities offer unique environments for addressing health disparities among young people, including those of LGB students. For many, the college years represent a time during which health disparities emerge28,29 and adverse changes occur in weight, dietary quality, physical activity, and other behaviors.30–38 For LGB people, this age is commonly when sexual identity is declared and assimilation into the LGB community occurs.39 Important postsecondary institutions that could act as platforms for intervention delivery include not only traditional 4-year universities but also 2-year community and technical colleges, which serve millions of students, particularly those from lower income and minority backgrounds.40,41The objective of this study was to characterize gender-specific weight-related disparities among college students by sexual orientation. We analyzed state survey data of nearly 34 000 students attending a wide array of 2- and 4-year colleges and universities in 2007 to 2011, including a subsample of more than 2000 LGB-identified and LGB-questioning participants. This research was intended to fill several gaps in the literature. For example, although a recent wave of studies11,19,22–25 were published after the release of the Institute of Medicine report,1 most of these studies used data from 1999 to 2007 and thus were not able to characterize disparities during the past 5 to 8 years (when important societal shifts in weight-related factors42,43 and social shifts regarding LGB issues occurred). Moreover, a majority of these studies focused not on the college years but rather on adulthood overall (e.g., 18–74 years) or on adolescence (e.g., 9th–12th grade). Finally, only a small number of studies have examined population-level LGB disparities in dietary intake or physical activity,11,20,25,26 which are critical factors to address in weight-related intervention strategies. Among the few population-based studies that have addressed diet and activity, unidimensional indicators have been used to assess fruit and vegetable consumption or moderate to vigorous intensity physical activity, but these studies have generally lacked characterization of other important dietary factors (e.g., frequency of soda, fast food, away-from-home eating, or breakfast consumption) or activities (e.g., strengthening activities, screen time).