Toward implementing virtual control groups in nonclinical safety studies

Historical data from control groups in animal toxicity studies is currently mainly used for comparative purposes to assess validity and robustness of study results. Due to the highly controlled environment in which the studies are performed and the homogeneity of the animal collectives it has been proposed to use the historical data for building so-called virtual control groups, which could replace partly or entirely the concurrent control. This would constitute a substantial contribution to the reduction of animal use in safety studies. Before the concept can be implemented, the prerequisites regarding data collection, curation and statistical evaluation together with a validation strategy need to be identified to avoid any impairment of the study outcome and subsequent consequences for human risk assessment. To further assess and develop the concept of virtual control groups the transatlantic think tank for toxicology (t⁴) sponsored a workshop with stakeholders from the pharmaceutical and chemical industry, academia, FDA, pharmaceutical, contract research organizations (CROs), and non-governmental organizations in Washington, which took place in March 2023. This report summarizes the current efforts of a European initiative to share, collect and curate animal control data in a centralized database and the first approaches to identify optimal matching criteria between virtual controls and the treatment arms of a study as well as first reflections about strategies for a qualification procedure and potential pitfalls of the concept.

Using in silico tools to predict flame retardant metabolites for more informative exposomics-based approaches

Introduction: The positive identification of xenobiotics and their metabolites in human biosamples is an integral aspect of exposomics research, yet challenges in compound annotation and identification continue to limit the feasibility of comprehensive identification of total chemical exposure. Nonetheless, the adoption of in silico tools such as metabolite prediction software, QSAR-ready structural conversion workflows, and molecular standards databases can aid in identifying novel compounds in untargeted mass spectral investigations, permitting the assessment of a more expansive pool of compounds for human health hazard. This strategy is particularly applicable when it comes to flame retardant chemicals. The population is ubiquitously exposed to flame retardants, and evidence implicates some of these compounds as developmental neurotoxicants, endocrine disruptors, reproductive toxicants, immunotoxicants, and carcinogens. However, many flame retardants are poorly characterized, have not been linked to a definitive mode of toxic action, and are known to share metabolic breakdown products which may themselves harbor toxicity. As U.S. regulatory bodies begin to pursue a subclass- based risk assessment of organohalogen flame retardants, little consideration has been paid to the role of potentially toxic metabolites, or to expanding the identification of parent flame retardants and their metabolic breakdown products in human biosamples to better inform the human health hazards imposed by these compounds. Methods: The purpose of this study is to utilize publicly available in silico tools to 1) characterize the structural and metabolic fates of proposed flame retardant classes, 2) predict first pass metabolites, 3) ascertain whether metabolic products segregate among parent flame retardant classification patterns, and 4) assess the existing coverage in of these compounds in mass spectral database. Results: We found that flame retardant classes as currently defined by the National Academies of Science, Engineering and Medicine (NASEM) are structurally diverse, with highly variable predicted pharmacokinetic properties and metabolic fates among member compounds. The vast majority of flame retardants (96%) and their predicted metabolites (99%) are not present in spectral databases, posing a challenge for identifying these compounds in human biosamples. However, we also demonstrate the utility of publicly available in silico methods in generating a fit for purpose synthetic spectral library for flame retardants and their metabolites that have yet to be identified in human biosamples. Discussion: In conclusion, exposomics studies making use of fit-for-purpose synthetic spectral databases will better resolve internal exposure and windows of vulnerability associated with complex exposures to flame retardant chemicals and perturbed neurodevelopmental, reproductive, and other associated apical human health impacts.

The Good, The Bad, and The Perplexing: Structural Alerts and Read-Across for Predicting Skin Sensitization Using Human Data

In our earlier work (Golden et al., 2021), we showed 70-80% accuracies for several skin sensitization computational tools using human data. Here, we expanded the data set using the NICEATM human skin sensitization database to create a final data set of 1355 discrete chemicals (largely negative, ∼70%). Using this expanded data set, we analyzed model performance and evaluated mispredictions using Toxtree (v 3.1.0), OECD QSAR Toolbox (v 4.5), VEGA's (1.2.0 BETA) CAESAR (v 2.1.7), and a k-nearest-neighbor (kNN) classification approach. We show that the accuracy on this data set was lower than previous estimates, with balanced accuracies being 63% and 65% for Toxtree and OECD QSAR Toolbox, respectively, 46% for VEGA, and 59% for a kNN approach, with the lower accuracy likely due to the higher percentage of nonsensitizing chemicals. Two hundred eighty seven chemicals were mispredicted by both Toxtree and OECD QSAR Toolbox, which was approximately 20% of the entire data set, and 84% of these were false positives. The absence or presence of metabolic simulation in OECD QSAR Toolbox made no overall difference. While Toxtree is known for overpredicting, 60% of the chemicals in the data set had no alert for skin sensitization, and a substantial number of these chemicals were in fact sensitizers, pointing to sensitization mechanisms not recognized by Toxtree. Interestingly, we observed that chemicals with more than one Toxtree alert were more likely to be nonsensitizers. Finally, a kNN approach tended to mispredict different chemicals than either OECD QSAR Toolbox or Toxtree, suggesting that there was additional information to be garnered from a kNN approach. Overall, the results demonstrate that while there is merit in structural alerts as well as QSAR or read-across approaches (perhaps even more so in their combination), additional improvement will require a more nuanced understanding of mechanisms of skin sensitization.

Abstract P1-13-13: Nuclear envelope Expression of the Oncogene Adipocyte-Associated Methionine Domain Containing Conveys Inferior Prognosis but Increased Sensitivity to Statins and Fluorouracil-Based Therapy

The sub-classification of invasive breast cancer into Integrated Clusters by a combined analysis of genomic change and expression profiling has revealed novel cancer drivers. The integrated Cluster 2 breast cancer sub-group represents a cohort with aggressive, largely estrogen receptor positive tumours with a high relapse rate. It is characterized by an amplification of chromosome 11 at the heart of which is a little studied gene which codes for the protein Adipocyte-Associated Methionine Domain Containing (AAMDC). Initial cell line and murine studies demonstrated oncogenic behaviours for AAMDC including increased proliferation and invasion, increased colony formation and anti-estrogen resistance. Downstream gene expression analysis showed the protein to modulate cholesterol biosynthesis, one carbon metabolism and mTOR signaling. To assess the clinical impact of differing levels and sub-localizations of AAMDC, immunohistochemistry for AAMDC was carried out using tissue microarrays from a cohort of 420 patients with invasive breast cancer. Expression was noted in a number of sub-cellular localizations including diffuse cytoplasm, nucleus and nuclear envelope. Using both dichotomous and continuous scoring, no significant association for any expression site with standard prognostic factors was identified including size, lymph node status, grade or receptor statuses. However, both cytoplasmic and nuclear envelope expressions correlated with significantly worse overall survival (p=0.04 and p=0.04 respectively) whereas nuclear expression showed a trend to better survival (p=0.06). Distant relapse and breast cancer deaths were lowest where there was nuclear expression but no nuclear envelope expression (4.7% and 4.7% respectively) but significantly higher for the reverse expression pattern (18.9%, p=0.02 and 17.6%, p=0.03 respectively). Considering the pre-clinical impact of AAMDC on genes involved in cholesterol biosynthesis, we studied the effects of statin prescription in the early disease setting in the context of AAMDC expression. Statins were found to be generally protective of relapse across the group. Only nuclear envelope AAMDC expression interacted, with a hazard ratio (HR) of 0.33 for distant relapse with high expressors, compared to a HR of 0.90 in low expression (p=0.02 for difference). Similarly, considering one carbon metabolism, we explored the impact of the anti-metabolite drug capecitabine compared to other chemotherapy treatments, largely taxane-based, in the metastatic setting. Again, only nuclear envelope expression interacted with median progression-free survivals on capecitabine of 2.0 v 12.2 months for low and high nuclear envelope expression respectively, p=0.03. In summary, AAMDC nuclear envelope expression correlates with poor prognosis which may be mitigated by statin administration in the early disease setting. This expression pattern also confers sensitivity to flurouracil-based metastatic treatment.

Citation Format: Andrew D. Redfern, Indunil Weerasena, Lisa Spalding, Monique Ong, Emily Golden, Eleanor Woodward, Pilar Blancafort. Nuclear envelope Expression of the Oncogene Adipocyte-Associated Methionine Domain Containing Conveys Inferior Prognosis but Increased Sensitivity to Statins and Fluorouracil-Based Therapy [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P1-13-13.

Darting across space and time: parametric modulators of sex-biased conditioned fear responses

Pavlovian fear conditioning is a widely used behavioral paradigm for studying associative learning in rodents. Despite early recognition that subjects may engage in a variety of both conditioned and unconditioned responses, the last several decades have seen the field narrow its focus to measure freezing as the sole indicator of conditioned fear. We previously reported that female rats were more likely than males to engage in darting, an escape-like conditioned response that is associated with heightened shock reactivity. To determine how experimental parameters contribute to the frequency of darting in both males and females, we manipulated factors such as chamber size, shock intensity, and number of trials. To better capture fear-related behavioral repertoires in our animals, we developed ScaredyRat, an open-source custom Python tool that analyzes Noldus Ethovision-generated raw data files to identify darters and quantify both conditioned and unconditioned responses. We found that, like freezing, conditioned darting occurrences scale with experimental alterations. While most darting occurs in females, we found that with an extended training protocol, darting can emerge in males as well. Collectively, our data suggest that darting reflects a behavioral switch in conditioned responding that is a product of an individual animal's sex, shock reactivity, and experimental parameters, underscoring the need for careful consideration of sex as a biological variable in classic learning paradigms.

Abstract P5-05-03: Adipocyte associated methionine domain containing (AAMDC): A nuclear envelope protein with predictive and prognostic potential in luminal breast cancer

Background Estrogen receptor (ER) positive breast cancers (BCs) are less likely to relapse than other types, due to a lower propensity to disseminate and to sensitivity to anti-estrogen drugs in the adjuvant setting. However, combined analysis of DNA mutation and mRNA expression profiles in BC identifies a number of Integrative Clusters (IntClus), one of which, IntClus2, is characterized by ER positivity but high relpase and mortality. A hallmark of IntClus2 tumours is an amplification of chromosome 11, at the center of which lies the gene for the protein AAMDC. Pre-clinical research shows this protein to drive proliferation, migration, colony formation, switching between glucose and lipid metabolism, folate metabolism and anti-estrogen resistance. We postulated that resultant clinical behaviours could include; high relapse and mortality, anti-estrogen resistance, an interaction with the protective effect on relapse from statins and sensitivity to fluorouracil (FU)-based therapies. Methods The retrospective study cohort comprised 1766 ER positive early BC patients treated 1994-2014. Patient and tumour demographic, statin prescription and treatment data were collated. Primary tumour tissue was available with AAMDC expression data on 419 patients. On noting nuclear (N), cytoplasmic (C) and nuclear envelope (NE) expression, separate intensity scores were attributed to each localization. Intensity score cut-points were based on providing statistically useable sub-group sizes for comparison. Results No significant correlations between BC biology and patterns of AAMDC expression were seen. Cytoplasmic AAMDC weakly linked to some aggressive features, including high grade, luminal B sub-type and progesterone receptor negativity, although less lymph node spread. In contrast, nuclear AAMDC associated with some less aggressive features, being less in high grade and luminal B cancers. Nuclear envelope AAMDC was rarer in the HER2 positive sub-type without other correlates. A trend to higher distant relapse was seen for NE +ive BCs (20 v 14%, p=0.09). Overall mortality was statistically higher for NE expression (54 v 44% mortality, p=0.04) and cytoplasmic expression (56 v 47% mortality, p=0.04) and a trend to lower mortality for nuclear expression (46 v 54%, p=0.06). Looking at combinatorial expression, BC deaths were significantly lower in the nuclear +ive/NE -ive phenotype (4.7%) than the nuclear -ive/NE -ive (19.5%, p=0.013), nuclear -ive/NE +ive (17.6%, p=0.017) or nuclear +ive/NE +ive phenotypes (19.3%, p=0.011).Considering the effects of statins on early BC outcome, overall our patients on statins had notably lower BC return rates (HR 0.31, p=0.004). Considering interactions with AAMDC, in high-risk NE +ive cancers statin protection was high (HR for relapse 0.33, p=0.032), compared to no protection in already low risk NE -ive tumours (HR 0.90, p=0.41). The hypothesis that AAMDC confers sensitivity to FU-based agents was confirmed with a correlation observed for longer responses to FU-based chemotherapy for increasing NE AAMDC expression (R=0.334), whereas no link was seen for other agents or other AAMDC expression sub-locations. The mean times on FU-based therapy for low, moderate and high NE expression were 2.0, 5.7 and 12.2 months respectively (p=0.02). This work indicates that AAMDC expression can BC affect outcome, identifying nuclear envelope located AAMDC as both associating with higher mortality and correlating with superior protection from statins as well as response to FU-based chemotherapies. This could guide metastatic chemotherapy selection for affected patients, implies NE positive BCs might preferentially benefit from adjuvant statins and suggests that AAMDC and NE-associated AAMDC partners may be future therapeutic targets.

Citation Format: Indunil Weerasena, Lisa Spalding, Benjamin F Dessauvagie, Emily Golden, Eleanor Woodward, Pilar Blancafort, Andrew Redfern. Adipocyte associated methionine domain containing (AAMDC): A nuclear envelope protein with predictive and prognostic potential in luminal breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P5-05-03.

Probabilistic risk assessment - the keystone for the future of toxicology

Safety sciences must cope with uncertainty of models and results as well as information gaps. Acknowledging this uncertainty necessitates embracing probabilities and accepting the remaining risk. Every toxicological tool delivers only probable results. Traditionally, this is taken into account by using uncertainty / assessment factors and worst-case / precautionary approaches and thresholds. Probabilistic methods and Bayesian approaches seek to characterize these uncertainties and promise to support better risk assessment and, thereby, improve risk management decisions. Actual assessments of uncertainty can be more realistic than worst-case scenarios and may allow less conservative safety margins. Most importantly, as soon as we agree on uncertainty, this defines room for improvement and allows a transition from traditional to new approach methods as an engineering exercise. The objective nature of these mathematical tools allows to assign each methodology its fair place in evidence integration, whether in the context of risk assessment, systematic reviews, or in the definition of an integrated testing strategy (ITS) / defined approach (DA) / integrated approach to testing and assessment (IATA). This article gives an overview of methods for probabilistic risk assessment and their application for exposure assessment, physiologically-based kinetic modelling, probability of hazard assessment (based on quantitative and read-across based structure-activity relationships, and mechanistic alerts from in vitro studies), individual susceptibility assessment, and evidence integration. Additional aspects are opportunities for uncertainty analysis of adverse outcome pathways and their relation to thresholds of toxicological concern. In conclusion, probabilistic risk assessment will be key for constructing a new toxicology paradigm – probably!

Evaluation of the global performance of eight in silico skin sensitization models using human data

Allergic contact dermatitis, or the clinical manifestation of skin sensitization, is a leading occupational hazard. Several testing approaches exist to assess skin sensitization, but in silico models are perhaps the most advantageous due to their high speed and low-cost results. Many in silico skin sensitization models exist, though many have only been tested against results from animal studies (e.g., LLNA); this creates uncertainty in human skin sensitization assessments in both a screening and regulatory context. This project’s aim was to evaluate the accuracy of eight in silico skin sensitization models against two human data sets: one highly curated (Basketter et al., 2014) and one screening level (HSDB). The binary skin sen­sitization status of each chemical in each of the two data sets was compared to the prediction from eight in silico skin sensitization tools (Toxtree, PredSkin, OECD’s QSAR Toolbox, UL’s REACHAcross™, Danish QSAR Database, TIMES-SS, and Lhasa Limited’s Derek Nexus). Models were assessed for coverage, accuracy, sensitivity, and specificity, as well as optimization features (e.g., probability of accuracy, applicability domain, etc.), if available. While there was a wide range of sensitivity and specificity, the models generally performed comparably to the LLNA in predicting human skin sensitization status (i.e., approximately 70-80% accuracy). Additionally, the models did not mispredict the same com­pounds, suggesting there might be an advantage in combining models. In silico skin sensitization models offer accurate and useful insights in a screening context; however, further improvements are necessary so these models may be con­sidered fully reliable for regulatory applications.

Avoiding Regrettable Substitutions: Green Toxicology for Sustainable Chemistry

Green chemistry seeks to design less hazardous chemicals, but many of the efforts to replace chemicals have resulted in so-called "Regrettable Substitutions", when a chemical with an unknown or unforeseen hazard is used to replace a chemical identified as problematic. Here, we discuss the literature on regrettable substitution and focus on an oft-mentioned case, Bisphenol A, which was replaced with Bisphenol S-and the lessons that can be learned from this history. In particular, we focus on how Green Toxicology can offer a way to make better substitutions.

The oncogene AAMDC links PI3K-AKT-mTOR signaling with metabolic reprograming in estrogen receptor-positive breast cancer

Adipogenesis associated Mth938 domain containing (AAMDC) represents an uncharacterized oncogene amplified in aggressive estrogen receptor-positive breast cancers. We uncover that AAMDC regulates the expression of several metabolic enzymes involved in the one-carbon folate and methionine cycles, and lipid metabolism. We show that AAMDC controls PI3K-AKT-mTOR signaling, regulating the translation of ATF4 and MYC and modulating the transcriptional activity of AAMDC-dependent promoters. High AAMDC expression is associated with sensitization to dactolisib and everolimus, and these PI3K-mTOR inhibitors exhibit synergistic interactions with anti-estrogens in IntClust2 models. Ectopic AAMDC expression is sufficient to activate AKT signaling, resulting in estrogen-independent tumor growth. Thus, AAMDC-overexpressing tumors may be sensitive to PI3K-mTORC1 blockers in combination with anti-estrogens. Lastly, we provide evidence that AAMDC can interact with the RabGTPase-activating protein RabGAP1L, and that AAMDC, RabGAP1L, and Rab7a colocalize in endolysosomes. The discovery of the RabGAP1L-AAMDC assembly platform provides insights for the design of selective blockers to target malignancies having the AAMDC amplification.

Mapping Chemical Respiratory Sensitization: How Useful Are Our Current Computational Tools?

Chemical respiratory sensitization is an immunological process that manifests clinically mostly as occupational asthma and is responsible for 1 in 6 cases of adult asthma, although this may be an underestimate of the prevalence, as it is under-diagnosed. Occupational asthma results in unemployment for roughly one-third of those affected due to severe health issues. Despite its high prevalence, chemical respiratory sensitization is difficult to predict, as there are currently no validated models and the mechanisms are not entirely understood, creating a significant challenge for regulatory bodies and industry alike. The Adverse Outcome Pathway (AOP) for respiratory sensitization is currently incomplete. However, some key events have been identified, and there is overlap with the comparatively well-characterized AOP for dermal sensitization. Because of this, and the fact that dermal sensitization is often assessed by in vivo, in chemico, or in silico methods, regulatory bodies are defaulting to the dermal sensitization status of chemicals as a proxy for respiratory sensitization status when evaluating chemical safety. We identified a data set of known human respiratory sensitizers, which we used to investigate the accuracy of a structural alert model, Toxtree, designed for skin sensitization and the Centre for Occupational and Environmental Health (COEH)'s model, a model developed specifically for occupational asthma. While both models had a reasonable level of accuracy, the COEH model achieved the highest balanced accuracy at 76%; when the models agreed, the overall accuracy was 87%. There were important differences between the models: Toxtree had superior performance for some structural alerts and some categories of well-characterized skin sensitizers, while the COEH model had high accuracy in identifying sensitizers that lacked identified skin sensitization reactivity domains. Overall, both models achieved respectable accuracy. However, neither model addresses potency, which, along with data quality, remains a hurdle, and the field must prioritize these issues to move forward.

Bidirectional perisomatic inhibitory plasticity of a Fos neuronal network

Behavioral experiences activate the Fos transcription factor (TF) in sparse populations of neurons that are critical for encoding and recalling specific events^1–3. However, there is limited understanding of the mechanisms by which experience drives circuit reorganization to establish a network of Fos-activated cells. It is also unknown if Fos is required in this process beyond serving as a marker of recent neural activity and, if so, which of its many gene targets underlie circuit reorganization. Here we demonstrate that when mice engage in spatial exploration of novel environments, perisomatic inhibition of Fos-expressing hippocampal CA1 pyramidal neurons by parvalbumin (PV)-interneurons (INs) is enhanced, while perisomatic inhibition by cholecystokinin (CCK)-INs is weakened. This bidirectional modulation of inhibition is abolished when the function of the Fos TF complex is disrupted. Single-cell RNA-sequencing, ribosome-associated mRNA profiling, and chromatin analyses, combined with electrophysiology, reveal that Fos activates the transcription of Scg2 (secretogranin II), a gene that encodes multiple distinct neuropeptides, to coordinate these changes in inhibition. As PV- and CCK-INs mediate distinct features of pyramidal cell activity^4–6, the Scg2-dependent reorganization of inhibitory synaptic input might be predicted to affect network function in vivo. Consistent with this prediction, hippocampal gamma rhythms and pyramidal cell coupling to CA1 theta are significantly altered with loss of Scg2. These findings reveal an instructive role for Fos and Scg2 in establishing a network of Fos-activated neurons via the rewiring of local inhibition to form a selectively modulated state. The opposing plasticity mechanisms on distinct inhibitory pathways may support the consolidation of memories over time.

Honeybee venom and melittin suppress growth factor receptor activation in HER2-enriched and triple-negative breast cancer

Despite decades of study, the molecular mechanisms and selectivity of the biomolecular components of honeybee (Apis mellifera) venom as anticancer agents remain largely unknown. Here, we demonstrate that honeybee venom and its major component melittin potently induce cell death, particularly in the aggressive triple-negative and HER2-enriched breast cancer subtypes. Honeybee venom and melittin suppress the activation of EGFR and HER2 by interfering with the phosphorylation of these receptors in the plasma membrane of breast carcinoma cells. Mutational studies reveal that a positively charged C-terminal melittin sequence mediates plasma membrane interaction and anticancer activity. Engineering of an RGD motif further enhances targeting of melittin to malignant cells with minimal toxicity to normal cells. Lastly, administration of melittin enhances the effect of docetaxel in suppressing breast tumor growth in an allograft model. Our work unveils a molecular mechanism underpinning the anticancer selectivity of melittin, and outlines treatment strategies to target aggressive breast cancers.

1169 Innovative Exposure to Sleep Medicine for Medical Students

Introduction

Lack of exposure to the field of Sleep Medicine at the medical student level hinders sleep training. Instead of the traditional didactic style, there is a need for innovative collaborative measures to spark interest in the younger generation of learners. The goal of this educational endeavor was to introduce medical students to the field of Sleep Medicine through the platform of Student Interest Group in Neurology (SIGN).

Methods

An interactive session was conducted for SIGN at the University of Minnesota. 24 second-year medical students were divided into 6 groups. The session consisted of introduction, videos of common sleep disorders and interactive briefing afterward. 5-point Likert scale pre and post-session surveys were administered to measure the level of knowledge regarding sleep, familiarity with diagnostic tools, available education, pathways to Sleep Medicine, learner’s interest and impact of the session. Wilcoxon matched-pairs signed-rank test was performed to compare pre- and post-surveys.

Results

There was a significant improvement in measures of students’ knowledge about sleep diagnostic modalities (p =7.8*10-5), education received (p= 3.2*10-5) and pathways to sleep medicine (p=4.1*10-5). Survey also showed improvement in students’ interest in pursuing a Sleep Medicine career (p=0.07). There was no difference in knowledge about the importance of sleep for health (p=0.69). All of the students found the session to be informative.

Conclusion

Early exposure to sleep disorders in interactive format was well received by the medical students with significant improvement in scores regarding sleep education, awareness of diagnostic modalities, career pathway and interest in sleep medicine (p=0.07). Integration of exposure to Sleep Medicine within the medical curriculum in an innovative format should be done to instigate interest in this field. Further larger studies are warranted to evaluate the changes in the students’ interest in the subspecialty with an introduction in the early stages of their career.

Support

 

Rab GTPases: Emerging Oncogenes and Tumor Suppressive Regulators for the Editing of Survival Pathways in Cancer

The Rab GTPase family of proteins are mediators of membrane trafficking, conferring identity to the cell membranes. Recently, Rab and Rab-associated factors have been recognized as major regulators of the intracellular positioning and activity of signaling pathways regulating cell growth, survival and programmed cell death or apoptosis. Membrane trafficking mediated by Rab proteins is controlled by intracellular localization of Rab proteins, Rab-membrane interactions and GTP-activation processes. Aberrant expression of Rab proteins has been reported in multiple cancers such as lung, brain and breast malignancies. Mutations in Rab-coding genes and/or post-translational modifications in their protein products disrupt the cellular vesicle trafficking network modulating tumorigenic potential, cellular migration and metastatic behavior. Conversely, Rabs also act as tumor suppressive factors inducing apoptosis and inhibiting angiogenesis. Deconstructing the signaling mechanisms modulated by Rab proteins during apoptosis could unveil underlying molecular mechanisms that may be exploited therapeutically to selectively target malignant cells.

Oxidation of cysteine 34 of plasma albumin as a biomarker of oxidative stress

Introduction: In order to better understand the physiological and pathophysiological roles of reactive oxygen species (ROS), multiple blood and urine biomarkers of oxidative stress have been developed. The single free thiol (Cys34) in plasma albumin is a useful biomarker of oxidative stress because thiol groups are particularly sensitive to oxidation by ROS. The primary aim of this study was to develop a gel electrophoresis-based method (mPEG assay) that would be more widely accessible than existing chromatography techniques to assay the oxidation state of albumin Cys34.Method: Blood samples were collected into a solution containing polyethylene glycol maleimide (malpeg). Plasma samples were divided into two aliquots, with a reducing agent added to one aliquot. Albumin bound to malpeg was separated from albumin by gel electrophoresis. The proportion of albumin in reduced form (-SH), disulphide form (-SSX) and irreversibly oxidised form (-SO₂, -SO₃) could then be calculated.Results: Data for the mPEG assay was comparable to data from chromatographic and mass spectrometric assays. The mPEG assay was more sensitive than the albumin carbonyl assay for the detection of changes in albumin oxidation level in response to exposure to hydrogen peroxide or hypochlorous acid. This assay could also be performed on small blood samples (less than 10 µL) from fingerprick, thus facilitating longitudinal tracking of changes in albumin Cys34 oxidation level.Conclusion: The mPEG assay is a user-friendly, highly sensitive, specific, cost-effective gel electrophoresis-based method for the assay of the oxidations state of albumin Cys34 as a biomarker of oxidative stress.HighlightsProtein thiol groups are sensitive to oxidation by reactive oxygen species.Plasma albumin contains a reduced cysteine residue (Cys34) sensitive to oxidation.A novel gel electrophoresis-based method (mPEG) has been developed to measure the oxidation state of Cys34.The mPEG assay can be run on a drop of blood collected by fingerprick.

Precision medicine by designer interference peptides: applications in oncology and molecular therapeutics

In molecular cancer therapeutics only 10% of known cancer gene products are targetable with current pharmacological agents. Major oncogenic drivers, such as MYC and KRAS proteins are frequently highly overexpressed or mutated in multiple human malignancies. However, despite their key role in oncogenesis, these proteins are hard to target with traditional small molecule drugs due to their large, featureless protein interfaces and lack of deep pockets. In addition, they are inaccessible to large biologicals, which are unable to cross cell membranes. Designer interference peptides (iPeps) represent emerging pharmacological agents created to block selective interactions between protein partners that are difficult to target with conventional small molecule chemicals or with large biologicals. iPeps have demonstrated successful inhibition of multiple oncogenic drivers with some now entering clinical settings. However, the clinical translation of iPeps has been hampered by certain intrinsic limitations including intracellular localization, targeting tissue specificity and pharmacological potency. Herein, we outline recent advances for the selective inhibition of major cancer oncoproteins via iPep approaches and discuss the development of multimodal peptides to overcome limitations of the first generations of iPeps. Since many protein–protein interfaces are cell-type specific, this approach opens the door to novel programmable, precision medicine tools in cancer research and treatment for selective manipulation and reprogramming of the cancer cell oncoproteome.

Triple-hit therapeutic approach for triple negative breast cancers using docetaxel nanoparticles, EN1-iPeps and RGD peptides

Triple negative breast cancers (TNBC) are aggressive malignancies for which chemotherapy is the only treatment option. Many TNBC acquire chemotherapy resistance, notably docetaxel, which has been associated with the overexpression of transcription factors (TFs), such as ENGRAILED1 (EN1). Here, we have developed a tumor delivery system for docetaxel-PGMA-PAA-nanoparticles and interference peptides designed to specifically inhibit EN1 (EN1-iPeps). To promote tumor specific targeting, we functionalized these nanoparticles with EN1-iPeps engineered with RGD sequences. We found that these peptides reduce cell viability and induce apoptosis in TNBC cells with negligible effects on normal cells (EN1^-). Moreover, EN1-RGD-iPeps-mediated nanoparticle internalization into breast cancer cells was via integrins and intravenous injection of this nanoformulation increased tumor accumulation. Furthermore, docetaxel nanoparticles functionalized with EN1-RGD-iPeps significantly reduced TNBC growth both in vitro and in vivo without showing toxicity. Our results suggest that this targeted nanoformulation represents a new and safe therapeutic approach for chemoresistant TNBCs.

Contrast-Enhanced 3D-FLAIR Imaging of the Optic Nerve and Optic Nerve Head: Novel Neuroimaging Findings of Idiopathic Intracranial Hypertension

BACKGROUND AND PURPOSE

The sensitivity of contrast-enhanced 3D-FLAIR has not been assessed in patients with idiopathic intracranial hypertension. The purpose of this study was to evaluate whether hyperintensity of the optic nerve/optic nerve head on contrast-enhanced 3D-FLAIR imaging is associated with papilledema in patients with idiopathic intracranial hypertension.

MATERIALS AND METHODS

A retrospective review was conducted from 2012 to 2015 of patients with clinically diagnosed idiopathic intracranial hypertension and age- and sex-matched controls who had MR imaging with contrast-enhanced 3D-FLAIR. Two neuroradiologists graded each optic nerve/optic nerve head on a scale of 0-3. This grade was then correlated with the Frisén Scale, an ophthalmologic scale used for grading papilledema from 0 (normal) to 5 (severe edema). To estimate the correlation between the MR imaging and Frisén scores, we calculated the Kendall τ coefficient.

RESULTS

Forty-six patients (3 men, 43 women) with idiopathic intracranial hypertension and 61 controls (5 men, 56 women) with normal findings on MR imaging were included in this study. For both eyes, there was moderate correlation between the 2 scales (right eye: τ = 0.47; 95% CI, 0.31-0.57; left eye: τ = 0.38; 95% CI, 0.24-0.49). Interreader reliability for MR imaging scores showed high interreader reliability (right eye: κ = 0.76; 95% CI, 0.55-0.88; left eye: κ = 0.87; 95% CI, 0.78-0.94). Contrast-enhanced 3D-FLAIR imaging correlates with the Frisén Scale for moderate-to-severe papilledema and less so for mild papilledema.

CONCLUSIONS

Hyperintensity of the optic nerve/optic nerve head on contrast-enhanced 3D-FLAIR is sensitive for the detection of papilledema in patients with idiopathic intracranial hypertension, which may be useful when prompt diagnosis is crucial.

Tumor penetrating peptides inhibiting MYC as a potent targeted therapeutic strategy for triple-negative breast cancers

Overexpression of MYC oncogene is highly prevalent in many malignancies such as aggressive triple-negative breast cancers (TNBCs) and it is associated with very poor outcome. Despite decades of research, attempts to effectively inhibit MYC, particularly with small molecules, still remain challenging due to the featureless nature of its protein structure. Herein, we describe the engineering of the dominant-negative MYC peptide (OmoMYC) linked to a functional penetrating 'Phylomer' peptide (FPPa) as a therapeutic strategy to inhibit MYC in TNBC. We found FPPa-OmoMYC to be a potent inducer of apoptosis (with IC₅₀ from 1-2 µM) in TNBC cells with negligible effects in non-tumorigenic cells. Transcriptome analysis of FPPa-OmoMYC-treated cells indicated that the fusion protein inhibited MYC-dependent networks, inducing dynamic changes in transcriptional, metabolic, and apoptotic processes. We demonstrated the efficacy of FPPa-OmoMYC in inhibiting breast cancer growth when injected orthotopically in TNBC allografts. Lastly, we identified strong pharmacological synergisms between FPPa-OmoMYC and chemotherapeutic agents. This study highlights a novel therapeutic approach to target highly aggressive and chemoresistant MYC-activated cancers.

Oxidative Stress and Cardiovascular Risk in Type 1 Diabetes Mellitus: Insights From the DCCT/EDIC Study

Background

Hyperglycemia leading to increased oxidative stress is implicated in the increased risk for the development of macrovascular and microvascular complications in patients with type 1 diabetes mellitus.

Methods and Results

A random subcohort of 349 participants was selected from the DCCT / EDIC (Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications) cohort. This included 320 controls and 29 cardiovascular disease cases that were augmented with 98 additional known cases to yield a case cohort of 447 participants (320 controls, 127 cases). Biosamples from DCCT baseline, year 1, and closeout of DCCT , and 1 to 2 years post‐ DCCT ( EDIC years 1 and 2) were measured for markers of oxidative stress, including plasma myeloperoxidase, paraoxonase activity, urinary F 2α isoprostanes, and its metabolite, 2,3 dinor‐8 iso prostaglandin F 2α . Following adjustment for glycated hemoblobin and weighting the observations inversely proportional to the sampling selection probabilities, higher paraoxonase activity, reflective of antioxidant activity, and 2,3 dinor‐8 iso prostaglandin F 2α , an oxidative marker, were significantly associated with lower risk of cardiovascular disease (−4.5% risk for 10% higher paraoxonase, P <0.003; −5.3% risk for 10% higher 2,3 dinor‐8 iso prostaglandin F 2α , P =0.0092). In contrast, the oxidative markers myeloperoxidase and F 2α isoprostanes were not significantly associated with cardiovascular disease after adjustment for glycated hemoblobin. There were no significant differences between DCCT intensive and conventional treatment groups in the change in all biomarkers across time segments.

Conclusions

Heightened antioxidant activity (rather than diminished oxidative stress markers) is associated with lower cardiovascular disease risk in type 1 diabetes mellitus, but these biomarkers did not change over time with intensification of glycemic control.

Clinical Trial Registration

URL : https://www.clinicaltrials.gov . Unique identifiers: NCT 00360815 and NCT 00360893.

Computational insights for the hydride transfer and distinctive roles of key residues in cholesterol oxidase

Cholesterol oxidase (ChOx), a member of the glucose-methanol-choline (GMC) family, catalyzes the oxidation of the substrate via a hydride transfer mechanism and concomitant reduction of the FAD cofactor. Unlike other GMC enzymes, the conserved His447 is not the catalytic base that deprotonates the substrate in ChOx. Our QM/MM MD simulations indicate that the Glu361 residue acts as a catalytic base facilitating the hydride transfer from the substrate to the cofactor. We find that two rationally chosen point mutations (His447Gln and His447Asn) cause notable decreases in the catalytic activity. The binding free energy calculations show that the Glu361 and His447 residues are important in substrate binding. We also performed high-level double-hybrid density functional theory simulations using small model systems, which support the QM/MM MD results. Our work provides a basis for unraveling the substrate oxidation mechanism in GMC enzymes in which the conserved histidine does not act as a base.

Production and characterization of recombinant perdeuterated cholesterol oxidase

Cholesterol oxidase (CO) is a FAD (flavin adenine dinucleotide) containing enzyme that catalyzes the oxidization and isomerization of cholesterol. Studies directed toward elucidating the catalytic mechanism of CO will provide an important general understanding of Flavin-assisted redox catalysis. Hydrogen atoms play an important role in enzyme catalysis; however, they are not readily visualized in protein X-ray diffraction structures. Neutron crystallography is an ideal method for directly visualizing hydrogen positions at moderate resolutions because hydrogen and deuterium have comparable neutron scattering lengths to other heavy atoms present in proteins. The negative coherent and large incoherent scattering lengths of hydrogen atoms in neutron diffraction experiments can be circumvented by replacing hydrogen atoms with its isotope, deuterium. The perdeuterated form of CO was successfully expressed from minimal medium, purified, and crystallized. X-ray crystallographic structures of the enzyme in the perdeuterated and hydrogenated states confirm that there are no apparent structural differences between the two enzyme forms. Kinetic assays demonstrate that perdeuterated and hydrogenated enzymes are functionally identical. Together, structural and functional studies indicate that the perdeuterated protein is suitable for structural studies by neutron crystallography directed at understanding the role of hydrogen atoms in enzyme catalysis.

High-resolution structures of cholesterol oxidase in the reduced state provide insights into redox stabilization

Cholesterol oxidase (CO) is a flavoenzyme that catalyzes the oxidation and isomerization of cholesterol to cholest-4-en-3-one. The reductive half reaction occurs via a hydride transfer from the substrate to the FAD cofactor. The structures of CO reduced with dithionite under aerobic conditions and in the presence of the substrate 2-propanol under both aerobic and anaerobic conditions are presented. The 1.32 Å resolution structure of the dithionite-reduced enzyme reveals a sulfite molecule covalently bound to the FAD cofactor. The isoalloxazine ring system displays a bent structure relative to that of the oxidized enzyme, and alternate conformations of a triad of aromatic residues near to the cofactor are evident. A 1.12 Å resolution anaerobically trapped reduced enzyme structure in the presence of 2-propanol does not show a similar bending of the flavin ring system, but does show alternate conformations of the aromatic triad. Additionally, a significant difference electron-density peak is observed within a covalent-bond distance of N5 of the flavin moiety, suggesting that a hydride-transfer event has occurred as a result of substrate oxidation trapping the flavin in the electron-rich reduced state. The hydride transfer generates a tetrahedral geometry about the flavin N5 atom. High-level density-functional theory calculations were performed to correlate the crystallographic findings with the energetics of this unusual arrangement of the flavin moiety. These calculations suggest that strong hydrogen-bond interactions between Gly120 and the flavin N5 centre may play an important role in these structural features.

Effect of prolonged methylprednisolone therapy in unresolving acute respiratory distress syndrome: a randomized controlled trial

CONTEXT

No pharmacological therapeutic protocol has been found effective in modifying the clinical course of acute respiratory distress syndrome (ARDS) and mortality remains greater than 50%.

OBJECTIVE

To determine the effects of prolonged methylprednisolone therapy on lung function and mortality in patients with unresolving ARDS.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Medical intensive care units of 4 medical centers.

PARTICIPANTS

Twenty-four patients with severe ARDS who had failed to improve lung injury score (LIS) by the seventh day of respiratory failure.

INTERVENTIONS

Sixteen patients received methylprednisolone and 8 received placebo. Methylprednisolone dose was initially 2 mg/kg per day and the duration of treatment was 32 days. Four patients whose LIS failed to improve by at least 1 point after 10 days of treatment were blindly crossed over to the alternative treatment.

MAIN OUTCOME MEASURES

Primary outcome measures were improvement in lung function and mortality. Secondary outcome measures were improvement in multiple organ dysfunction syndrome (MODS) and development of nosocomial infections.

RESULTS

Physiological characteristics at the onset of ARDS were similar in both groups. At study entry (day 9 [SD, 3] of ARDS), the 2 groups had similar LIS, ratios of PaO2 to fraction of inspired oxygen (FIO2), and MODS scores. Changes observed by study day 10 for methylprednisolone vs placebo were as follows: reduced LIS (mean [SEM], 1.7 [0.1] vs 3.0 [0.2]; P<.001); improved ratio of PaO2 to FIO2 (mean [SEM], 262 [19] vs 148 [35]; P<.001); decreased MODS score (mean [SEM], 0.7 [0.2] vs 1.8 [0.3]; P<.001); and successful extubation (7 vs 0; P=.05). For the treatment group vs the placebo group, mortality associated with the intensive care unit was 0 (0%) of 16 vs 5 (62%) of 8 (P=.002) and hospital-associated mortality was 2 (12%) of 16 vs 5 (62%) of 8 (P=.03). The rate of infections per day of treatment was similar in both groups, and pneumonia was frequently detected in the absence of fever.

CONCLUSIONS

In this study, prolonged administration of methylprednisolone in patients with unresolving ARDS was associated with improvement in lung injury and MODS scores and reduced mortality.

Nutrition knowledge and obesity of adults in community residences

Variation in nutrition knowledge of adults with mild or moderate mental retardation (30 obese, 27 nonobese) from four community agencies was examined as a function of their body mass and level of mental retardation. They completed a nutrition knowledge test adapted for individuals with mental retardation. Multiple regression analyses revealed significant effects of level of mental retardation and body mass on nutrition knowledge. Adults with mild mental retardation possessed greater nutrition knowledge than did those with moderate mental retardation, and obese individuals possessed more knowledge than did nonobese individuals. The unexpected relation between nutrition knowledge and degree of obesity implies an influential role for environmental factors in the development of obesity.

Prevalence, incidence, and correlates of syphilis seroreactivity in multiethnic San Francisco neighborhoods

To examine the extent of infection with syphilis in an inner-city community, we determined the prevalence, incidence, and correlates of syphilis seroreactivity in a representative sample of unmarried whites, African Americans, and Hispanics living in San Francisco during 1988 to 1989 and again 1 year later in 1989 to 1990. One thousand seven hundred seventy single men and women aged 20 to 44 were surveyed in a random household sample drawn from three neighborhoods of varying geographic and cultural characteristics. Syphilitic infection was determined by testing specimens with the microhemagglutination assay for antibodies to Treponema pallidum (MHA-TP). Of blood samples available from 1262 participants from the initial survey, 32 (2.5%) were MHA-TP reactive. After adjustment for age, a reactive syphilis serology was significantly predicted (P < 0.05) by African American race, homosexual activity (men), and less education. In homosexually active men, lifetime number of male sex partners and the presence of antibody to the human immunodeficiency virus (HIV) significantly predicted syphilis seroreactivity (P < 0.01). One year later, of 841 specimens available for testing, an additional 13 (1.5%) had become MHA-TP reactive. Eleven (85%) of the new cases were in heterosexual men and women. Although San Francisco citywide incidence data indicate that syphilis may be decreasing for the city as a whole, incidence data on a community level suggests that syphilitic infection is increasing in high-risk heterosexual communities. Thus, syphilis prevention programs should rely on serologic testing at the community level to plan effective intervention strategies.

Correlates of condom use among black, Hispanic, and white heterosexuals in San Francisco: the AMEN longitudinal survey. AIDS in Multi-Ethnic Neighborhoods survey

We examined correlates of condom use among heterosexual whites, blacks, and Hispanics (ages 20-45 years) with an human immunodeficiency virus (HIV) risk factor in a community-based longitudinal sample (San Francisco; n = 716). Lag models were used to examine hypothesized antecedents of condom use at wave 2. High levels of condom use were associated with labeling one's sexual behavior as risky for HIV infection, high levels of condom enjoyment and commitment to use condoms, good sexual communication practices, gender (trend), and marital status. The results support the need for wide-ranging intervention programs that stimulate people to make personal risk assessments, teach basic sexual skills, and direct those in need of intensive help to appropriate agencies.

Crack cocaine use and high-risk behaviors among sexually active black adolescents

The recent spread of crack cocaine use among inner-city teenagers has been accompanied by dramatic increases in juvenile delinquency and sexually transmitted diseases (STDs) among teenagers. This study examined the prevalence of five factors which promote STDs, including human immunodeficiency virus (HIV), among a sample of sexually active black adolescent crack users and non-users from the San Francisco Bay Area. Significant differences were observed between these groups with respect to history of engaging in sexual intercourse under the influence of drugs or alcohol, exchanging sexual favors for drugs or money, condom use in the most recent sexual encounter, and having five or more sexual partners in the last year. Approximately 63% of all respondents reported engaging in at least one of these risk behaviors. In multiple logistic regression analysis, reporting one or more of these STD/HIV risk behaviors was significantly associated with crack use and having one or more relatives who used drugs. Intervention efforts need to address both individual and environmental risk factors in order to reduce teens' risk for STDs, including HIV.

Prevalence and correlates of herpes simplex infections. The population-based AIDS in Multiethnic Neighborhoods Study

OBJECTIVE

To examine the extent and correlates of infection with herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) in an inner-city community, we studied the prevalence of antibodies to these viruses and their association with risk behaviors in a representative sample of unmarried white, black, and Hispanic adults living in San Francisco, Calif.

DESIGN

Cross-sectional, community-based, random household survey.

PARTICIPANTS

In 1988 and 1989, we surveyed 1770 unmarried men and women aged 20 to 44 years from three San Francisco neighborhoods of varying geographic and cultural characteristics.

MAIN OUTCOME MEASURES

HSV-1 and HSV-2 antibodies based on an immunodot assay using type-specific glycoproteins gG-1 and gG-2.

RESULTS

Of blood samples from 1212 participants available for testing, 750 (62%) had HSV-1 antibodies and 400 (33%) had HSV-2 antibodies. After controlling for other variables, HSV-1 antibody was significantly correlated (P less than .05) with older age (in heterosexual men, women, and homosexually active men), less education (in heterosexual men and women), and Hispanic (especially those not born in the United States) or black race. HSV-2 antibody was significantly correlated (P less than .05) with female gender, number of lifetime sexual partners and older age (in heterosexual men and women), and low levels of education and black or Hispanic race (in women). Among those with antibody to HSV-2, only 28 (19%) of 149 men and 32 (13%) of 251 women reported a history of genital herpes. However, most men (62%) and women (84%) who reported a history of genital herpes had HSV-2 antibodies. We observed a similar pattern (low sensitivity and moderate specificity) for a history of facial herpes and the presence of HSV-1 antibodies. After controlling for other variables, HSV-2 antibodies were associated with a lower frequency of HSV-1 antibodies among homosexual men infected with the human immunodeficiency virus.

CONCLUSIONS

HSV-1 antibodies were found in nearly two thirds of single urban adults and were most common among Hispanics not born in the United States. HSV-2 antibodies were found in one third of this population and were associated with risk behaviors for sexually transmitted diseases. For both facial and genital herpes infections, self-reporting of infection was very insensitive and moderately specific.

Risk for AIDS in multiethnic neighborhoods in San Francisco, California. The population-based AMEN Study

To examine the actual and potential spread of human immunodeficiency virus (HIV) from an acquired immunodeficiency syndrome (AIDS) epicenter to surrounding neighborhoods, we studied the prevalence of the viral infection and AIDS risk behaviors from 1988 to 1989 in a representative sample of unmarried whites, African Americans, and Hispanics living in San Francisco. We surveyed 1,770 single men and women aged 20 to 44 years (a 64% response rate) in a random household sample drawn from 3 neighborhoods of varying geographic and cultural proximity to the Castro District where the San Francisco epidemic began. Of 1,369 with blood tests, 69 (5%) had HIV antibodies; all but 5 of these reported either homosexual activity (32% HIV-positive; 95% confidence interval [CI] = 23%, 41%), injection drug use (5% HIV-positive; CI = 1%, 14%), or both (59% HIV-positive; CI 42%, 74%). Homosexual activity was more common among white men than among African-American or Hispanic men, but the proportion of those infected was similar in the 3 races. Both the prevalence of homosexually active men and the proportion infected were much lower in the 2 more outlying neighborhoods. Risk behaviors in the past year for acquiring HIV heterosexually--sex with an HIV-infected person or homosexually active man or injection drug user, unprotected sexual intercourse with more than 4 partners, and (as a proxy) having a sexually transmitted disease--were assessed in 1,573 neighborhood residents who were themselves neither homosexually active men nor injection drug users. The prevalence of reporting at least 1 of these risk behaviors was 12% overall, and race-gender estimates ranged from 5% among Hispanic women to 21% among white women. We conclude that in San Francisco, infection with HIV is rare among people who are neither homosexually active nor injection drug users, but the potential for the use spread of infection is substantial, as 12% of this group reported important risk behaviors for acquiring the virus heterosexually.

An Analysis of the Predictability of Hypoxemia Following Vertical Banded Gastroplasty

Postoperative (post-op) hypoxemia is unpredictable, often undetected by physical examination, sometimes fatal. We studied 45 morbidly obese patients with an average age of 37, including 16 smokers, having vertical banded gastroplasty (VBG) for useful preoperative (preop) predictor(s) of post-op hypoxemia during the first five days following VBG. Patient blood gases (arterial blood oxygen, P&infa;O&inf2; in mmHg), pre-op and five post-op days (POD), after 30 min in room air were: pre-op, 85 +/- 9; POD1, 63 +/- 9*; POD2, 61 +/- 9*; POD3, 63 +/- 10*; POD4, 63 +/- 9* POD5, 64 +/- 1 * (* p < 0.05, Student's t-test compared with pre-op). Linear regression showed no practical, predictive value for P.02 for age, Body Mass Index (BMI), pulmonary function tests (PFTs), smokers or preop P&infa;O&inf2;. Post-op atelectasis occurred in 84% of patients, mostly the posterior basilar regions on chest X-ray. No patient developed clinically diagnostic pneumonia. VBG patients experienced profound hypoxemia post-op, the lowest on POD2. There is no reliable method to predict which patient may develop severe hypoxemia. It is, therefore, extremely helpful to uniformly monitor P&infa;O&inf2; post-op in morbidly obese patients.

Postthaw stability of fibrinogen in cryoprecipitate stored between 1 and 6 degrees C

The fibrinogen activity in thawed cryoprecipitate stored between 1 and 6 degrees C is maintained essentially unchanged in most bags for a month. Occasionally, a bag will have a reduction in fibrinogen. If pooling has not occurred, thawed cryoprecipitate should be useful as a source of fibrinogen for a period of time considerably in excess of the 6 hours allowed for its use as a source of factor VIII or von Willebrand factor.

Hereditary hemorrhagic telangiectasia. A family study

The authors report a comprehensive evaluation of the hemostatic system in eight related patients with hereditary hemorrhagic telangiectasia (HHT). Unlike in previous reports, they could find no evidence for abnormalities in platelet aggregation or for qualitative abnormalities of the Factor VIII complex. The authors did identify a subgroup of the more severely affected patients in whom Factor VIIIc levels were increased, with shortened activated partial thromboplastin times (APTTs) associated with mild elevations of antithrombin III.

Cat-eye syndrome with different marker chromosomes in a mother and daughter

Except for atypical eye findings in the daughter, a mother and daughter with bisatellited marker chromosomes had abnormalities consistent with cat-eye syndrome. The mother's marker chromosome (mar number 1) is derived from one 22 and another acrocentric, possibly also a 22; the daughter's marker (mar number 2) may be an iso-dicentric, inv-dup (22) derivative of mar number 1. The mother has a tertiary trisomy translocation chromosome composed of at least one and perhaps two copies of 22pter----q11.2, whereas the daughter clearly has a secondary trisomy 22pter----q11.2 isochromosome, confirming this region as a cause of cat-eye syndrome. Results of hybridization using a unique sequence probe localized to 22q11 are consistent with the interpretation that both ends of both marker chromosomes are derived from 22.

The use of methacholine inhalation, methacholine skin testing, distilled water inhalation challenge and eosinophil counts in the evaluation of patients presenting with cough and/or nonwheezing dyspnea

Twenty-four patients presenting with cough and/or nonwheezing dyspnea were evaluated with methacholine inhalation challenge (MC), distilled water inhalation challenge (DC), intracutaneous tests to varying concentrations of methacholine, total eosinophil counts (TEC), sinus and chest x-rays. We found a statistically significant difference (P less than .005) in the mean TEC in those patients with a positive MC test and those with a negative test. Hyperreactivity of the airways to methacholine in asthmatics is not found in the skin. Distilled water inhalation did not serve to substitute for MC as a test of hyperreactive airways. The TEC is an excellent screening test as a predictor of patients with cough or dyspnea who have hyperreactive airways.

Correlation between serial pulmonary function tests and fiberoptic bronchoscopy in patients with Pneumocystis carinii pneumonia and the acquired immune deficiency syndrome

The records of 9 adult male patients with the acquired immune deficiency syndrome (AIDS) and biopsy-proved Pneumocystis carinii pneumonia were reviewed to determine the correlation between serial pulmonary function tests and the presence or absence of Pneumocystis organisms in subsequent bronchoscopy specimens. At diagnosis, total lung capacity (TLC) or vital capacity (VC) was abnormally low in 4 patients (44%) and diffusing capacity (DLCO) was abnormally low in 8 patients (89%). The ratio of forced expiratory volume in one second (FEV1) to forced vital capacity (FVC) was elevated in all patients. After 21 to 47 days of specific therapy for Pneumocystis pneumonia, changes in DLCO, TLC, VC, and FEV1/FVC did not correlate with the presence or absence of Pneumocystis organisms in bronchoscopy specimens from 7 patients. However, changes in DLCO 105 to 258 days after diagnosis seemed to correlate with the late response to treatment in 6 patients. These results suggest that decisions to terminate specific therapy for Pneumocystis pneumonia in patients with AIDS should not be based on short-term changes in pulmonary function.