The use and misuse of the SCOFF screening measure over two decades: a systematic literature review.

PURPOSE: The SCOFF questionnaire was designed as a simple, memorable screening tool to raise suspicion that a person might have an eating disorder. It is over 20 years since the creation of the SCOFF, during which time it has been widely used. Considering this, we wish to review the use of the SCOFF in peer-reviewed scientific journals, and to assess whether it is being used appropriately in the manner in which it was originally devised and tested. METHODS: The Preferred Reporting Items for a Systematic Review and Meta-analysis (PRISMA) guidelines were followed, and all search strategies and methods were determined before the onset of the study. PubMed and Wiley Online Library were searched using the terms SCOFF and eating. Two reviewers were involved in the reviewing process. Criteria for appropriate use of the SCOFF were formalised with the tool's original authors. RESULTS: 180 articles were included in the final review. 48 articles had used the SCOFF appropriately, 117 articles inappropriately and 15 articles had been mixed in the appropriateness of their use. CONCLUSION: This systematic review highlights the inappropriate use of the SCOFF in diverse languages and settings. When used correctly the SCOFF has made a significant contribution to the understanding of eating disorders and its simplicity has been applauded and led to widespread use. However in over two-thirds of studies, the use of the SCOFF was inappropriate and the paper highlights how and in what way it was misused, Guidelines for the appropriate use of the SCOFF are stated. Future validation and avenues of research are suggested. LEVEL OF EVIDENCE: Level I.

Circadian rhythms of macrophages are altered by the acidic pH of the tumor microenvironment.

Macrophages are prime therapeutic targets due to their pro-tumorigenic and immunosuppressive functions in tumors, but varying efficacy of therapeutic approaches targeting macrophages highlights our incomplete understanding of how the tumor microenvironment (TME) can influence regulation of macrophages. The circadian clock is a key internal regulator of macrophage function, but how circadian rhythms of macrophages may be influenced by the tumor microenvironment remains unknown. We found that conditions associated with the TME such as polarizing stimuli, acidic pH, and elevated lactate concentrations can each alter circadian rhythms in macrophages. Circadian rhythms were enhanced in pro-resolution macrophages but suppressed in pro-inflammatory macrophages, while acidic pH had divergent effects on circadian rhythms depending on macrophage phenotype. While cyclic AMP (cAMP) has been reported to play a role in macrophage response to acidic pH, our results indicate that pH-driven changes in circadian rhythms are not mediated solely by the cAMP signaling pathway. Remarkably, clock correlation distance analysis of tumor-associated macrophages (TAMs) revealed evidence of circadian disorder in TAMs. This is the first report providing evidence that circadian rhythms of macrophages are altered within the TME. Our data suggest that heterogeneity in circadian rhythms at the population level may underlie this circadian disorder. Finally, we sought to determine how circadian regulation of macrophages impacts tumorigenesis, and found that tumor growth was suppressed when macrophages had a functional circadian clock. Our work demonstrates a novel mechanism by which the tumor microenvironment can influence macrophage biology through altering circadian rhythms, and the contribution of circadian rhythms in macrophages to suppressing tumor growth.

Do macrophages follow the beat of circadian rhythm in TIME (Tumor Immune Microenvironment)?

Advances in cancer research have made clear the critical role of the immune response in clearing tumors. This breakthrough in scientific understanding was heralded by the success of immune checkpoint blockade (ICB) therapies such as anti-programmed cell death protein 1 (PD-1)/ programmed death-ligand 1 (PD-L1) and anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4), as well as the success of chimeric antigen receptor (CAR) T cells in treating liquid tumors. Thus, much effort has been made to further understand the role of the immune response in tumor progression, and how we may target it to treat cancer. Macrophages are a component of the tumor immune microenvironment (TIME) that can promote tumor growth both indirectly, by suppressing T cell responses necessary for tumor killing, as well as directly, through deposition of extracellular matrix and promotion of angiogenesis. Thus, understanding regulation of macrophages within the tumor microenvironment (TME) is key to targeting them for immunotherapy. However, circadian rhythms (24-hour cycles) are a fundamental aspect of macrophage biology that have yet to be investigated for their role in macrophage-mediated suppression of the anti-tumor immune response Circadian rhythms regulate macrophage-mediated immune responses through time-of-day-dependent regulation of macrophage function. A better understanding of the circadian biology of macrophages in the context of the TME may allow us to exploit synergy between existing and upcoming treatments and circadian regulation of immunity.

Microfluidic Tools for Probing Fungal-Microbial Interactions at the Cellular Level.

Filamentous fungi are successful inhabitants of soil and play a major role in soil ecosystems, such as in the decomposition of organic and inorganic matter, as well as regulation of nutrient levels. There they also find numerous opportunities to interact with a variety of other microbes such as bacteria or other fungi. Studying fungal interactions at the cellular level, however, can be challenging owing to the black box-like nature of soil. New microfluidic tools are being developed for the study of fungal interactions; two platforms designed to study bacterial-fungal and fungal-fungal interactions are highlighted. Within these microchannels, fungal-microbial interactions can be monitored in controlled physico-chemical environments at higher temporal and spatial resolution than previously possible. Application of these tools have yielded numerous novel biological insights, such as the observation of bacterial polar attachment to hyphae or revealing uncharacterised fungal-fungal antagonisms. A key feature of these methodologies regards the ease of use of this tool by non-experts, yielding highly translatable technologies for use in microbiology labs.

MYC Ran Up the Clock: The Complex Interplay between MYC and the Molecular Circadian Clock in Cancer.

The MYC oncoprotein and its family members N-MYC and L-MYC are known to drive a wide variety of human cancers. Emerging evidence suggests that MYC has a bi-directional relationship with the molecular clock in cancer. The molecular clock is responsible for circadian (~24 h) rhythms in most eukaryotic cells and organisms, as a mechanism to adapt to light/dark cycles. Disruption of human circadian rhythms, such as through shift work, may serve as a risk factor for cancer, but connections with oncogenic drivers such as MYC were previously not well understood. In this review, we examine recent evidence that MYC in cancer cells can disrupt the molecular clock; and conversely, that molecular clock disruption in cancer can deregulate and elevate MYC. Since MYC and the molecular clock control many of the same processes, we then consider competition between MYC and the molecular clock in several select aspects of tumor biology, including chromatin state, global transcriptional profile, metabolic rewiring, and immune infiltrate in the tumor. Finally, we discuss how the molecular clock can be monitored or diagnosed in human tumors, and how MYC inhibition could potentially restore molecular clock function. Further study of the relationship between the molecular clock and MYC in cancer may reveal previously unsuspected vulnerabilities which could lead to new treatment strategies.

Publisher Correction: Natural and directed antigenic drift of the H1 influenza virus hemagglutinin stalk domain.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Publisher Correction: Natural and directed antigenic drift of the H1 influenza virus hemagglutinin stalk domain.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

Representaciones familiares en relación al uso y dependencia de drogas en adolescentes. El caso de zonas rurales / Family representations in relation to drug use and dependence in adolescents. The case of rural areas

Este trabajo indaga las representaciones sociales de familiares de adolescentes en situación de consumo problemático en relación al uso y dependencia de sustancias psicoactivas en zonas rurales del Valle de Lerma, Salta. Los propósitos del mismo implican identificar y describir las representaciones sociales de grupos familiares en relación a las drogodependencias como fenómeno asociado a la adolescencia, y a la particularidad del contexto rural, tomando como base de análisis a la Familia como Institución Social, la existencia de estrategias de detección y afrontamiento y la Accesibilidad al Sistema de Salud. Para ello, se construye una Teoría Fundamentada, junto a las familias, aplicando instrumentos propios de la investigación cualitativa; entrevistas individuales y grupales, y técnicas que permiten el registro audiovisual de las percepciones, imágenes y conceptos asociados. Los resultados obtenidos permitieron obtener un conocimiento socialmente elaborado y compartido, que brinda aproximaciones para definir y comprender el problema de las drogodependencias en adolescentes desde la perspectiva familiar en tanto fenómeno sanitario y socio comunitario, enriqueciendo la literatura pre existente, en tanto explora dimensiones psicosociales del consumo de drogas en adolescentes, facilitando el análisis de la influencia que ejerce la comunidad en particular sobre la problemática y viceversa. Finalmente, se busca contribuir a la toma de decisiones para alcanzar la equidad en el ámbito de la Salud Publica, promoviendo programas que favorezcan la creación y optimizacion de redes sociales, así también como la elaboración de programas socio sanitarios que compensen la falta de instituciones de salud especializadas en Drogodependencias en zonas rurales del Valle de Lerma

Natural and directed antigenic drift of the H1 influenza virus hemagglutinin stalk domain.

The induction of antibodies specific for the influenza HA protein stalk domain is being pursued as a universal strategy against influenza virus infections. However, little work has been done looking at natural or induced antigenic variability in this domain and the effects on viral fitness. We analyzed human H1 HA head and stalk domain sequences and found substantial variability in both, although variability was highest in the head region. Furthermore, using human immune sera from pandemic A/California/04/2009 immune subjects and mAbs specific for the stalk domain, viruses were selected in vitro containing mutations in both domains that partially contributed to immune evasion. Recombinant viruses encoding amino acid changes in the HA stalk domain replicated well in vitro, and viruses incorporating two of the stalk mutations retained pathogenicity in vivo. These findings demonstrate that the HA protein stalk domain can undergo limited drift under immune pressure and the viruses can retain fitness and virulence in vivo, findings which are important to consider in the context of vaccination targeting this domain.

Antigenicity of the 2015-2016 seasonal H1N1 human influenza virus HA and NA proteins.

Antigenic drift of the hemagglutinin (HA) and neuraminidase (NA) influenza virus proteins contributes to reduced vaccine efficacy. To analyze antigenic drift in human seasonal H1N1 viruses derived from the 2009 pandemic H1N1 virus (pH1N1-like viruses) accounts for the limited effectiveness (around 40%) of vaccination against pH1N1-like viruses during the 2015-2016 season, nasal washes/swabs collected from adult subjects in the Rochester, NY area, were used to sequence and isolate the circulating viruses. The HA and NA proteins from viruses circulating during the 2015-2016 season encoded eighteen and fourteen amino acid differences, respectively, when compared to A/California/04/2009, a strain circulating at the origin of the 2009 pandemic. The circulating strains belonged to subclade 6B.1, defined by HA amino acid substitutions S101N, S179N, and I233T. Hemagglutination-inhibiting (HAI) and HA-specific neutralizing serum antibody (Ab) titers from around 50% of pH1N1-like virus-infected subjects and immune ferrets were 2-4 fold lower for the 2015-2016 circulating strains compared to the vaccine strain. In addition, using a luminex-based mPlex HA assay, the binding of human sera from subjects infected with pH1N1-like viruses to the HA proteins from circulating and vaccine strains was not identical, strongly suggesting antigenic differences in the HA protein. Additionally, NA inhibition (NAI) Ab titers in human sera from pH1N1-like virus-infected subjects increased after the infection and there were measurable antigenic differences between the NA protein of circulating strains and the vaccine strain using both ferret and human antisera. Despite having been vaccinated, infected subjects exhibited low HAI Ab titers against the vaccine and circulating strains. This suggests that poor responses to the H1N1 component of the vaccine as well as antigenic differences in the HA and NA proteins of currently circulating pH1N1-like viruses could be contributing to risk of infection even after vaccination.

Functional Evolution of Influenza Virus NS1 Protein in Currently Circulating Human 2009 Pandemic H1N1 Viruses.

In 2009, a novel H1N1 influenza virus emerged in humans, causing a global pandemic. It was previously shown that the NS1 protein from this human 2009 pandemic H1N1 (pH1N1) virus was an effective interferon (IFN) antagonist but could not inhibit general host gene expression, unlike other NS1 proteins from seasonal human H1N1 and H3N2 viruses. Here we show that the NS1 protein from currently circulating pH1N1 viruses has evolved to encode 6 amino acid changes (E55K, L90I, I123V, E125D, K131E, and N205S) with respect to the original protein. Notably, these 6 residue changes restore the ability of pH1N1 NS1 to inhibit general host gene expression, mainly by their ability to restore binding to the cellular factor CPSF30. This is the first report describing the ability of the pH1N1 NS1 protein to naturally acquire mutations that restore this function. Importantly, a recombinant pH1N1 virus containing these 6 amino acid changes in the NS1 protein (pH1N1/NSs-6mut) inhibited host IFN and proinflammatory responses to a greater extent than that with the parental virus (pH1N1/NS1-wt), yet virus titers were not significantly increased in cell cultures or in mouse lungs, and the disease was partially attenuated. The pH1N1/NSs-6mut virus grew similarly to pH1N1/NSs-wt in mouse lungs, but infection with pH1N1/NSs-6mut induced lower levels of proinflammatory cytokines, likely due to a general inhibition of gene expression mediated by the mutated NS1 protein. This lower level of inflammation induced by the pH1N1/NSs-6mut virus likely accounts for the attenuated disease phenotype and may represent a host-virus adaptation affecting influenza virus pathogenesis.IMPORTANCE Seasonal influenza A viruses (IAVs) are among the most common causes of respiratory infections in humans. In addition, occasional pandemics are caused when IAVs circulating in other species emerge in the human population. In 2009, a swine-origin H1N1 IAV (pH1N1) was transmitted to humans, infecting people then and up to the present. It was previously shown that the NS1 protein from the 2009 pandemic H1N1 (pH1N1) virus is not able to inhibit general gene expression. However, currently circulating pH1N1 viruses have evolved to encode 6 amino acid changes (E55K, L90I, I123V, E125D, K131E, and N205S) that allow the NS1 protein of contemporary pH1N1 strains to inhibit host gene expression, which correlates with its ability to interact with CPSF30. Infection with a recombinant pH1N1 virus encoding these 6 amino acid changes (pH1N1/NSs-6mut) induced lower levels of proinflammatory cytokines, resulting in viral attenuation in vivo This might represent an adaptation of pH1N1 virus to humans.

Intraductal Delivery to the Rabbit Mammary Gland.

Localized intraductal treatments for breast cancer offer potential advantages, including efficient delivery to the tumor and reduced systemic toxicity and adverse effects1,2,3,4,5,6,7. However, several challenges remain before these treatments can be applied more widely. The development and validation of intraductal therapeutics in an appropriate animal model facilitate the development of intraductal therapeutic strategies for patients. While the mouse mammary gland has been widely used as a model system of mammary development and tumorigenesis, the anatomy is distinct from the human gland. A larger animal model, such as the rabbit, may serve as a better model for mammary gland structure and intraductal therapeutic development. In contrast to mice, in which ten ductal trees are spatially distributed along the body axis, each terminating in a separate teat, the rabbit mammary gland more closely resembles the human gland, with multiple overlapping ductal systems that exit through separate openings in one teat. Here, we present minimally invasive methods for the delivery of reagents directly into the rabbit mammary duct and for visualization of the delivery itself with high-resolution ultrasound imaging.

Therapeutic HPV Cancer Vaccine Targeted to CD40 Elicits Effective CD8+ T-cell Immunity.

Human papillomavirus (HPV), particularly HPV16 and HPV18, can cause cancers in diverse anatomical sites, including the anogenital and oropharyngeal (throat) regions. Therefore, development of safe and clinically effective therapeutic vaccines is an important goal. Herein, we show that a recombinant fusion protein of a humanized antibody to CD40 fused to HPV16.E6/7 (αCD40-HPV16.E6/7) can evoke HPV16.E6/7-specific CD8+ and CD4+ T-cell responses in head-and-neck cancer patients in vitro and in human CD40 transgenic (hCD40Tg) mice in vivo The combination of αCD40-HPV16.E6/7 and poly(I:C) efficiently primed HPV16.E6/7-specific T cells, particularly CD8+ T cells, in hCD40Tg mice. Inclusion of montanide enhanced HPV16.E6/7-specific CD4+, but not CD8+, T-cell responses. Poly(I:C) plus αCD40-HPV16.E6/7 was sufficient to mount both preventative and therapeutic immunity against TC-1 tumors in hCD40Tg mice, significantly increasing the frequency of HPV16-specific CD8+ CTLs in the tumors, but not in peripheral blood. In line with this, tumor volume inversely correlated with the frequency of HPV16.E6/7-specific CD8+ T cells in tumors, but not in blood. These data suggest that CD40-targeting vaccines for HPV-associated malignancies can provide a highly immunogenic platform with a strong likelihood of clinical benefit. Data from this study offer strong support for the development of CD40-targeting vaccines for other cancers in the future. Cancer Immunol Res; 4(10); 823-34. ©2016 AACR.

The Development of White-Asian Categorization: Contributions from Skin Color and Other Physiognomic Cues.

We examined the development of racial categorizations of faces spanning the European-East Asian ("White-Asian") categorical continuum in children between the ages of four and nine as well as adults. We employed a stimulus set that independently varied skin color and other aspects of facial physiognomy, allowing the contribution of each to be assessed independently and in interaction with each other. Results demonstrated substantial development across this age range in children's ability to draw on both sorts of cue, with over twice as much variance explained by stimulus variation in adults than children. Nonetheless, children were clearly sensitive to both skin color and other aspects of facial physiognomy, suggesting that understanding of the White-Asian category boundary develops in a somewhat different way than understanding of the White-Black category boundary, in which attention to features other than skin color appear only somewhat later. Discussion focuses on the implications of these findings for theories of social categorization.

Skin Care.

Aging skin is among the most common patient concerns in a facial plastic surgery practice. Ultraviolet (UV)-induced damage expedites the pace of intrinsic aging, resulting in many of the visible signs of aging, such as rough skin texture, pigmentation irregularities, fine and deep wrinkling, and inelasticity. Primary prevention of UV and environmental damage with proper skin care and the use of sunscreen are critical. There is great interest in topically applied products to reverse or delay the visible signs of photoaging. We discuss the most common topically applied agents for photoaging, reviewing their mechanisms and supporting evidence.

Endoscopic suture retriever for endolaryngeal keel placement in treatment of anterior glottic webs.

INTRODUCTION: Endoscopic placement of a laryngeal keel has traditionally required the use of a Lichtenberger endo-extralaryngeal needle passer, which is not universally available. We discuss a safe and technically simple alternate technique using an endoscopic suture retriever through a percutaneously placed angiocatheter that obviates the need for the Lichtenberger instrument. STUDY DESIGN: Case series. MATERIALS AND METHODS: Two 14-gauge angiocatheters were passed through the anterior neck under telescopic visualization of the larynx. The suture retriever was inserted through the catheter and deployed within the larynx to withdraw a Prolene suture that was threaded through a Silastic keel. The keel was then tied in position over a sterile button on the anterior neck. RESULTS: This procedure was performed on 2 patients with excellent outcomes in both cases. CONCLUSION: Endoscopic keel placement is a widely used procedure for treating anterior glottic webs and requires suture passage from within the larynx to the anterior neck to secure the keel into position. This is the first report of an exo-endolaryngeal suture retriever for placement of a laryngeal keel. This technique provides a safe, reliable, and efficient alternative to endo-extralaryngeal needle puncture and uses materials that are available in many operating room settings.

Chemoradiotherapy-induced upregulation of PD-1 antagonizes immunity to HPV-related oropharyngeal cancer.

While viral antigens in human papillomavirus (HPV)-related oropharyngeal cancer (HPVOPC) are attractive targets for immunotherapy, the effects of existing standard-of-care therapies on immune responses to HPV are poorly understood. We serially sampled blood from patients with stage III-IV oropharyngeal cancer undergoing concomitant chemoradiotherapy with or without induction chemotherapy. Circulating immunocytes including CD4(+) and CD8(+) T cells, regulatory T cells (Treg), and myeloid-derived suppressor cells (MDSC) were profiled by flow cytometry. Antigen-specific T-cell responses were measured in response to HPV16 E6 and E7 peptide pools. The role of PD-1 signaling in treatment-related immunosuppression was functionally defined by performing HPV-specific T-cell assays in the presence of blocking antibody. While HPV-specific T-cell responses were present in 13 of 18 patients before treatment, 10 of 13 patients lost these responses within 3 months after chemoradiotherapy. Chemoradiotherapy decreased circulating T cells and markedly elevated MDSCs. PD-1 expression on CD4(+) T cells increased by nearly 2.5-fold after chemoradiotherapy, and ex vivo culture with PD-1-blocking antibody enhanced HPV-specific T-cell responses in 8 of 18 samples tested. Chemoradiotherapy suppresses circulating immune responses in patients with HPVOPC by unfavorably altering effector:suppressor immunocyte ratios and upregulating PD-1 expression on CD4(+) T cells. These data strongly support testing of PD-1-blocking agents in combination with standard-of-care chemoradiotherapy for HPVOPC.

Tumor-expressed inducible nitric oxide synthase controls induction of functional myeloid-derived suppressor cells through modulation of vascular endothelial growth factor release.

Inducible NO synthase (iNOS) is a hallmark of chronic inflammation that is also overexpressed in melanoma and other cancers. Whereas iNOS is a known effector of myeloid-derived suppressor cell (MDSC)-mediated immunosuppression, its pivotal position at the interface of inflammation and cancer also makes it an attractive candidate regulator of MDSC recruitment. We hypothesized that tumor-expressed iNOS controls MDSC accumulation and acquisition of suppressive activity in melanoma. CD11b(+)GR1(+) MDSC derived from mouse bone marrow cells cultured in the presence of MT-RET-1 mouse melanoma cells or conditioned supernatants expressed STAT3 and reactive oxygen species (ROS) and efficiently suppressed T cell proliferation. Inhibition of tumor-expressed iNOS with the small molecule inhibitor L-NIL blocked accumulation of STAT3/ROS-expressing MDSC, and abolished their suppressive function. Experiments with vascular endothelial growth factor (VEGF)-depleting Ab and recombinant VEGF identified a key role for VEGF in the iNOS-dependent induction of MDSC. These findings were further validated in mice bearing transplantable MT-RET-1 melanoma, in which L-NIL normalized elevated serum VEGF levels; downregulated activated STAT3 and ROS production in MDSC; and reversed tumor-mediated immunosuppression. These beneficial effects were not observed in iNOS knockout mice, suggesting L-NIL acts primarily on tumor- rather than host-expressed iNOS to regulate MDSC function. A significant decrease in tumor growth and a trend toward increased tumor-infiltrating CD8(+) T cells were also observed in MT-RET transgenic mice bearing spontaneous tumors. These data suggest a critical role for tumor-expressed iNOS in the recruitment and induction of functional MDSC by modulation of tumor VEGF secretion and upregulation of STAT3 and ROS in MDSC.

Identification of CITED2 as a negative regulator of fracture healing.

The transcription regulator CITED2 (CBP/p300-Interacting-Transactivator-with-ED-rich-tail-2) is known to suppress genes mediating angiogenesis and extracellular matrix (ECM) remodeling. However, it is unclear whether CITED2 has a role in controlling skeletal repair or remodeling. We tested the hypothesis that CITED2 functions in bone fracture healing by suppressing the expression of genes critical to ECM remodeling, angiogenesis and osteogenesis, importantly the matrix metalloproteinases (MMPs). Three hours following mandibular osteotomy or sham surgery of adult rats, osteotomy fronts were harvested and the expression of CITED2 and genes associated with fracture healing was ascertained by quantitative PCR. In parallel, gain-of-function studies examined the effect of overexpressing CITED2 on the expression and activity of several MMPs. In the fractured mandible, CITED2 expression was inversely related to the expression of MMP-2, -3, -9, -13, VEGF, HIF-1alpha, M-CSF, RANK-L, and OPG. Consistent with this, the over-expression of CITED2 in osteoblasts inhibited the expression and activity of MMP-2, -3, -9, and -13. Taken together, the studies suggest that CITED2 is a critical upstream regulator of fracture healing. The suppression of CITED2 early after fracture may allow an optimal initiation of the healing response.

Evidence for non-traditional activation of complement factor C3 during murine liver regeneration.

UNLABELLED: Complement signaling has been implicated as important for normal hepatic regeneration. However, the specific mechanism by which complement is activated during liver regeneration remains undefined. To address this question, we investigated the hepatic regenerative response to partial hepatectomy in wildtype mice, C3-, C4-, and factor B-null mice, and C4-null mice treated with a factor B neutralizing antibody (mAb 1379). The results showed that following partial hepatectomy, C3-null mice exhibit reduced hepatic regeneration compared to wildtype mice as assessed by quantification of hepatic cyclin D1 expression and hepatocellular DNA synthesis and mitosis. In contrast, C4-null mice and factor B-null mice demonstrated normal liver regeneration. Moreover, animals in which all of the traditional upstream C3 activation pathways were disrupted, i.e. C4-null mice treated with mAb 1379, exhibited normal C3 activation and hepatocellular proliferation following partial hepatectomy. In order to define candidate non-traditional mechanisms of C3 activation during liver regeneration, plasmin and thrombin were investigated for their abilities to activate C3 in mouse plasma in vitro. The results showed that both proteases are capable of initiating C3 activation, and that plasmin can do so independent of the classical and alternative pathways. CONCLUSIONS: These results show that C3 is required for a normal hepatic regenerative response, but that disruption of the classical- or lectin-dependent pathways (C4-dependent), the alternative pathway (factor B-dependent), or all of these pathways does not impair the hepatic regenerative response, and indicate that non-traditional mechanisms by which C3 is activated during hepatic regeneration must exist. In vitro analysis raises the possibility that plasmin may contribute to non-traditional complement activation during liver regeneration in vivo.