A Nationwide Survey of Educational Resource Utilization and Perception Among Internal Medicine Residents.

BACKGROUND: New virtual resources ("novel resources") have been incorporated into medical education. No recent large studies about their use and perception among internal medicine (IM) residents exist. OBJECTIVE: Characterize the use and perceived helpfulness of educational resources. DESIGN: Nationwide survey from December 2019 to March 2020. PARTICIPANTS: IM residents in the USA. MAIN MEASURES: Residents were surveyed on their use and their perceived helpfulness of resources for both attaining general medical knowledge and for point-of-care (POC) learning. Traditional resources included board review resources, clinical experience, digital clinical resources (e.g., UpToDate), journal articles, pocket references, professional guidelines, textbooks, and residency curricula. Novel resources included Twitter, video streaming platforms (e.g., YouTube), online blogs, podcasts, and Wikipedia. KEY RESULTS: We had 662 respondents from 55 residency programs across 26 states. On average, residents used 9 total resources (7 traditional and 2 novel). Digital clinical resources and clinical experience were used by all residents and found helpful by the highest percentage of residents (96% and 94%, respectively). Journal articles were next (used by 90%), followed by board review resources and residency curricula (both used by 85%). Their perceived helpfulness varied, from 90% for board review resources, to 66% for journal articles and 64% for residency curricula, the lowest perceived helpfulness of any traditional resource. Podcasts and video streaming platforms were used as frequently as textbooks (58-59%), but were rated as helpful more frequently (75% and 82% vs 66%, respectively). CONCLUSIONS: Digital clinical resources, video streaming platforms, and podcasts were perceived as helpful, underscoring the importance of ensuring their integration into medical education to complement clinical experience and other traditional resources which remain highly valued by residents. IMPORTANCE: Our findings can inform residency programs as they transition to virtual curricula in the wake of the COVID-19 pandemic.

Intrapatient viral diversity and treatment outcome in patients with genotype 3a hepatitis C virus infection on sofosbuvir-containing regimens.

Treatment with the direct-acting antiviral agent (DAA) sofosbuvir (SOF), an NS5B inhibitor, and velpatasvir (VEL), an NS5A inhibitor, demonstrates viral cure rates of ≥95% in hepatitis C virus (HCV) genotypes (GT) 1-6. Here, we investigated intrapatient HCV diversity in NS5A and NS5B using Shannon entropy to examine the relationship between viral diversity and treatment outcome. At baseline, HCV diversity was lowest in patients infected with HCV GT3 as compared to the other GTs, and viral diversity was greater in NS5A than NS5B (P < .0001). Treatment outcome with SOF/VEL or the comparator regimen of SOF with ribavirin (RBV) was not correlated with baseline diversity. However, among persons treated with SOF/VEL, a decrease in diversity from baseline was observed at relapse in the majority virologic failures, consistent with a viral bottleneck event at relapse. In contrast, an increase in diversity was observed in 27% of SOF+RBV virologic failures. We investigated whether the increase in diversity was due to an increase in the transition rate, one mode of potential RBV-mediated mutagenesis; however, we found no evidence of this mechanism. Overall, we did not observe that viral diversity at baseline influenced treatment outcome, but the diversity changes observed at relapse can improve our understanding of RBV viral suppression in vivo.

Vpx-containing dendritic cell vaccine induces CTLs and reactivates latent HIV-1 in vitro.

Eradication of human immunodeficiency virus-1 (HIV-1) from an infected individual requires a means of inducing production of virus from latently infected cells and stimulating an immune response against the infected cells. We report the development of lentiviral vectors that transduce dendritic cells (DCs) to both induce production of virus from latently infected cells and stimulate antigen-specific cytotoxic T lymphocytes (CTLs). The vectors package Vpx, a lentiviral accessory protein that counteracts the SAMHD1-mediated block to DC transduction, allowing for long-term expression of vector-encoded proteins. The vectors encode influenza or HIV-1-derived epitopes fused via a self-cleaving peptide to CD40L that releases the peptide into the endoplasmic reticulum for entry into the antigen presentation pathway. Expression of CD40L caused transduced DCs to mature and produce Th1-skewing cytokines. The DCs presented antigen to CD8 T cells, enhancing antigen-specific CTLs. Coculture of the transduced DCs with latently infected cells induced high-level virus production, an effect that was mediated by tumor necrosis factor alpha. The ability of a DC vaccine to reactivate latent HIV-1 and stimulate an adaptive immune response provide a means to reduce the size of the latent reservoir in patients. This strategy can also be applied to develop DC vaccines for other diseases.

Characterization of modified pearl millet (Pennisetum typhoides) starch.

Pearl millet starch (Pennisetum typhoides) was isolated and subjected to hydrothermal, acidic and enzymatic modifications. Native and various modified starches were characterized in terms of yield, moisture, protein, ash, bulk density, swelling power, solubility, colour, sediment volume, gel consistency, water binding capacity, pasting properties, freeze thaw stability and paste clarity. Hydrothermal modification (HTMS) caused an increase in swelling power and solubility. L value was higher for acid and enzymatically modified starches (EMS). A significant reduction (p ≤ 0.05) in sediment volume and water binding capacity was observed for acid modified starch (AMS) and EMS. Peak viscosity values declined for all modifications. However, EMS and AMS showed an improved freeze-thaw stability and paste clarity.

Development of a model to investigate the effects of prolonged ischaemia on the muscles of mastication of male Sprague Dawley rats.

OBJECTIVE: The aims of this study were to develop a novel rodent model of masticatory muscle ischaemia via unilateral ligation of the external carotid artery (ECA), and to undertake a preliminary investigation to characterize its downstream effects on mechanosensitivity and cellular features of the masseter and temporalis muscles. DESIGN: The right ECA of 18 male Sprague-Dawley rats was ligated under general anaesthesia. Mechanical detection thresholds (MDTs) at the masseter and temporalis bilaterally were measured immediately before ECA ligation and after euthanasia at 10-, 20-, and 35-days (n = 6 rats/timepoint). Tissue samples from both muscles and sides were harvested for histological analyses and for assessing changes in the expression of markers of hypoxia and muscle degeneration (Hif-1α, VegfA, and Fbxo32) via real time PCR. Data were analyzed using mixed effect models and non-parametric tests. Statistical significance was set at p < 0.05. RESULTS: MDTs were higher in the right than left hemiface (p = 0.009) after 20 days. Histological changes indicative of muscle degeneration and fibrosis were observed in the right muscles. Hif-1α, VegfA, and Fbxo32 were more highly expressed in the masseter than temporalis muscles (all p < 0.05). Hif-1α and, VegfA did not change significantly with time in all muscles (all p > 0.05). Fbxo32 expression gradually increased in the right masseter (p = 0.024) and left temporalis (p = 0.05). CONCLUSIONS: ECA ligation in rats induced hyposensitivity in the homolateral hemiface after 20 days accompanied by tissue degenerative changes. Our findings support the use of this model to study pathophysiologic mechanisms of masticatory muscle ischaemia in larger investigations.

Provision of smoking cessation support for patients following a diagnosis of cancer in Ireland.

There is growing evidence that smoking cessation (SC) improves outcomes following diagnosis of cancer. Notwithstanding adverse outcomes, a significant number of those diagnosed with cancer continue to smoke. Our objective was to document the SC services provided for patients with cancer by specialist adult cancer hospitals across Ireland, a country with a stated tobacco endgame goal. A cross-sectional survey based on recent national clinical guidelines was used to determine SC care delivery across eight adult cancer specialist hospitals, and one specialist radiotherapy centre. Qualtrics was used. The response rate was 88.9% with data reported from seven cancer hospitals and one specialist radiotherapy centre, all indicating they had some SC related provision (100%). Stop smoking medications were provided to cancer inpatients in two hospitals, at outpatients and attending day ward services in one hospital. Smokers with cancer were referred automatically to the SC service in two hospitals at diagnosis. While stop smoking medications were available 24 h a day in five hospitals, most did not stock all three (Nicotine Replacement Therapy, Bupropion, Varenicline). One hospital advised they had data on uptake of SC services for smokers with cancer but were unable to provide detail. There is considerable variation in SC information and services provided to cancer patients across adult cancer specialist centres in Ireland, reflecting the suboptimal practice of smoking cessation for patients with cancer found in the limited international audits. Such audits are essential to demonstrate service gaps and provide a baseline for service improvement.

Analysis of Perception of Students and Faculty on Case Based Early Clinical Exposure in First Year Medical Students.

Early clinical exposure (ECE) is a novel strategy for medical colleges to bridge the gap between basic and clinical sciences. There are few studies that explain student's and faculty's perspective on ECE. This study compares the ECE models (Case-based and Video-based case) in terms of benefits and challenges. This cross-over comparative study with 120 medical students of MBBS Batch 2019 and 8 facilitators was conducted in Government medical college, Pali, Rajasthan, India from September 2020 to March 2021. Entire batch was divided into two groups. In a hospital environment, one group was taught by an actual case (patient) of a specific topic, while another group was taught in a classroom setting by a video-based case. The students' and faculty's perspectives on Case-Based Early Clinical Exposure (CBECE) were documented using a pre-tested questionnaire and evaluated on a Likert scale. Finally, both groups were given assessment questions and the process was repeated in the following session of case based early clinical exposure, but with switched groups. Majority of the students (98.3%) agreed CBECE as more effective for attentiveness, retention, correlation of clinical knowledge with theoretical knowledge and communication. Most of the students (43.0%) believed that learning is limited due to lack of repeatability as compare with video-based case. Most of the facilitators found CBECE as effective tool for the development of attitude and communication skills of the students. CBECE can be implemented with limited sessions for sensitization of students about health care setup, importance of empathetic behavior, communication skill and better correlation of preclinical subjects in the context of disease.

Tumor-specific killer cells in paraneoplastic cerebellar degeneration.

Models for immune-mediated tumor regression in mice have defined an essential role for cytotoxic T lymphocytes (CTLs); however, naturally occurring tumor immunity in humans is poorly understood. Patients with paraneoplastic cerebellar degeneration (PCD) provide an opportunity to explore the mechanisms underlying tumor immunity to breast and ovarian cancer. Although tumor immunity and autoimmune neuronal degeneration in PCD correlates with a specific antibody response to the tumor and brain antigen cdr2, this humoral response has not been shown to be pathogenic. Here we present evidence for a specific cellular immune response in PCD patients. We have detected expanded populations of MHC class I-restricted cdr2-specific CTLs in the blood of 3/3 HLA-A2.1+ PCD patients, providing the first description, to our knowledge, of tumor-specific CTLs using primary human cells in a simple recall assay. Cross-presentation of apoptotic cells by dendritic cells also led to a potent CTL response. These results indicate a model whereby immature dendritic cells that engulf apoptotic tumor cells can mature and migrate to draining lymph organs where they could induce a CTL response to tissue-restricted antigens. In PCD, peripheral activation of cdr2-specific CTLs is likely to contribute to the subsequent development of the autoimmune neuronal degeneration.

Dendritic cells are potent antigen-presenting cells for microbial superantigens.

Dendritic cells are a small subset of human blood mononuclear cells that are potent stimulators of several T cell functions. Here we show they are 10-50-fold more potent than monocytes or B cells in inducing T cell responses to a panel of superantigens. Furthermore, dendritic cells can present femtomolar concentrations of superantigen to T cells even at numbers where other antigen-presenting cells (APCs) are inactive. Although dendritic cells express very high levels of the major histocompatibility complex products that are required to present superantigens, it is only necessary to pulse these APCs for 1 hour with picomolar levels of one superantigen, staphylococcal enterotoxin B, to maximally activate T cells. Our results suggest that very small amounts of superantigen will be immunogenic in vivo if presented on dendritic cells.

Interleukin 1 production during accessory cell-dependent mitogenesis of T lymphocytes.

We have studied the control and significance of IL-1 production in human leukocyte cultures during accessory cell-dependent, T lymphocyte mitogenesis using sensitive bioassays and immunolabeling techniques. In primary antigen-dependent systems like the MLR, IL-1 production was not detected in accessory cells (monocytes, dendritic cells) or T cells, suggesting that it is not an early product in these responses. However, monocytes could be induced to make IL-1 after interacting with sensitized antigen-specific T cells. Both alloreactive T cell clones or freshly prepared lymphoblasts induced IL-1 provided the monocytes carried the HLA-DR antigens to which the T cells were initially sensitized. Even in these circumstances, dendritic cells and B cells failed to make IL-1. The mechanism whereby activated T cells induce IL-1 in monocytes was explored. Supernatants from cocultures of monocytes and T cells or several recombinant cytokines induced little or no IL-1. A more potent antigen independent pathway of IL-1 induction was identified. IL-1 could be induced in third-party HLA-DR nonspecific monocytes in cocultures of alloreactive T cell clones or blasts and HLA-DR-specific dendritic cells. The induction was factor independent since dendritic cells and T blasts placed in a chamber separate from third-party monocytes by a semipermeable membrane did not induce monocyte IL-1. These results suggest that a cell contact mechanism rather than an IL-1-inducing factor leads to IL-1 production. The role of IL-1 in T cell proliferation was tested with a polyclonal anti-IL-1 antibody. The antibody failed to block the proliferation of primary T cells, or alloreactive T cell clones and blasts stimulated with HLA-specific monocytes or dendritic cells, even though IL-1 in the medium was neutralized.

Inactivated influenza virus, when presented on dendritic cells, elicits human CD8+ cytolytic T cell responses.

Inactivated or subunit virus preparations have been excellent vaccines for inducing antibody responses. Generation of cytolytic T cell responses, however, is thought to require replicating virus, primarily to provide sufficiently large amounts of cytoplasmic proteins for processing and presentation on major histocompatibility complex class I molecules by antigen-presenting cells. Potent human CD8+ cytolytic T cell responses to live replicating influenza A virus are generated when dendritic cells are used as the antigen-presenting cells. Here, we demonstrate that dendritic cells pulsed with poorly replicating, heat- or ultraviolet-inactivated influenza virus, induce equally strong CD8+ cytolytic T lymphocyte responses. The cytotoxic T lymphocytes are generated in the apparent absence of CD4+ helper cells or exogenous cytokines. Active viral protein synthesis is not required to charge class I molecules on dendritic cells. When pulsed with inactivated virus, < 1% of dendritic cells express nonstructural protein 1, which is only synthesized in the infectious cycle. To be optimally effective, however, the inactivated virus must retain its fusogenic activity, and presumably access the cytoplasm of dendritic cells. The data indicate, therefore, that dendritic cells require only small amounts of viral protein to charge class I molecules, most likely via traditional class I processing pathways. These results reopen the potential use of inactivated virus preparations as immunogens for cytotoxic T lymphocyte responses.

Antigen-specific inhibition of effector T cell function in humans after injection of immature dendritic cells.

Immunostimulatory properties of dendritic cells (DCs) are linked to their maturation state. Injection of mature DCs rapidly enhances antigen-specific CD4+ and CD8+ T cell immunity in humans. Here we describe the immune response to a single injection of immature DCs pulsed with influenza matrix peptide (MP) and keyhole limpet hemocyanin (KLH) in two healthy subjects. In contrast to prior findings using mature DCs, injection of immature DCs in both subjects led to the specific inhibition of MP-specific CD8+ T cell effector function in freshly isolated T cells and the appearance of MP-specific interleukin 10-producing cells. When pre- and postimmunization T cells were boosted in culture, there were greater numbers of MP-specific major histocompatibility complex tetramer-binding cells after immunization, but these had reduced interferon production and lacked killer activity. These data demonstrate the feasibility of antigen-specific inhibition of effector T cell function in vivo in humans and urge caution with the use of immature DCs when trying to enhance tumor or microbial immunity.

Small amounts of superantigen, when presented on dendritic cells, are sufficient to initiate T cell responses.

Dendritic cells are potent antigen-presenting cells for several primary immune responses and therefore provide an opportunity for evaluating the amounts of cell-associated antigens that are required for inducing T cell-mediated immunity. Because dendritic cells express very high levels of major histocompatibility complex (MHC) class II products, it has been assumed that high levels of ligands bound to MHC products ("signal one") are needed to stimulate quiescent T cells. Here we describe quantitative aspects underlying the stimulation of human blood T cells by a bacterial superantigen, staphylococcal enterotoxin A (SEA). The advantages of superantigens for quantitative studies of signal one are that these ligands: (a) engage MHC class II and the T cell receptor but do not require processing; (b) are efficiently presented to large numbers of quiescent T cells; and (c) can be pulsed onto dendritic cells before their application to T cells. Thus one can relate amounts of dendritic cell-associated SEA to subsequent lymphocyte stimulation. Using radioiodinated SEA, we noted that dendritic cells can bind 30-200 times more superantigen than B cells and monocytes. Nevertheless, this high SEA binding does not underlie the strong potency of dendritic cells to present antigen to T cells. Dendritic cells can sensitize quiescent T cells, isolated using monoclonals to appropriate CD45R epitopes, after a pulse of SEA that occupies a maximum of 0.1% of surface MHC class II molecules. This corresponds to an average of 2,000 molecules per dendritic cell. At these low doses of bound SEA, monoclonal antibodies to CD3, CD4, and CD28 almost completely block T cell proliferation. In addition to suggesting new roles for MHC class II on dendritic cells, especially the capture and retention of ligands at low external concentrations, the data reveal that primary T cells can generate a response to exceptionally low levels of signal one as long as these are delivered on dendritic cells.

Consequences of cell death: exposure to necrotic tumor cells, but not primary tissue cells or apoptotic cells, induces the maturation of immunostimulatory dendritic cells.

Cell death by necrosis is typically associated with inflammation, in contrast to apoptosis. We have identified additional distinctions between the two types of death that occur at the level of dendritic cells (DCs) and which influence the induction of immunity. DCs must undergo changes termed maturation to act as potent antigen-presenting cells. Here, we investigated whether exposure to apoptotic or necrotic cells affected DC maturation. We found that immature DCs efficiently phagocytose a variety of apoptotic and necrotic tumor cells. However, only exposure to the latter induces maturation. The mature DCs express high levels of the DC-restricted markers CD83 and lysosome-associated membrane glycoprotein (DC-LAMP) and the costimulatory molecules CD40 and CD86. Furthermore, they develop into powerful stimulators of both CD4(+) and CD8(+) T cells. Cross-presentation of antigens to CD8(+) T cells occurs after uptake of apoptotic cells. We demonstrate here that optimal cross-presentation of antigens from tumor cells requires two steps: phagocytosis of apoptotic cells by immature DCs, which provides antigenic peptides for major histocompatibility complex class I and class II presentation, and a maturation signal that is delivered by exposure to necrotic tumor cells, their supernatants, or standard maturation stimuli, e.g., monocyte-conditioned medium. Thus, DCs are able to distinguish two types of tumor cell death, with necrosis providing a control that is critical for the initiation of immunity.

Immature dendritic cells phagocytose apoptotic cells via alphavbeta5 and CD36, and cross-present antigens to cytotoxic T lymphocytes.

Dendritic cells, but not macrophages, efficiently phagocytose apoptotic cells and cross-present viral, tumor, and self-antigens to CD8(+) T cells. This in vitro pathway corresponds to the in vivo phenomena of cross-priming and cross-tolerance. Here, we demonstrate that phagocytosis of apoptotic cells is restricted to the immature stage of dendritic cell (DC) development, and that this process is accompanied by the expression of a unique profile of receptors, in particular the alphavbeta5 integrin and CD36. Upon maturation, these receptors and, in turn, the phagocytic capacity of DCs, are downmodulated. Macrophages engulf apoptotic cells more efficiently than DCs, and although they express many receptors that mediate this uptake, they lack the alphavbeta5 integrin. Furthermore, in contrast to DCs, macrophages fail to cross-present antigenic material contained within the engulfed apoptotic cells. Thus, DCs use unique pathways for the phagocytosis, processing, and presentation of antigen derived from apoptotic cells on class I major histocompatibility complex. We suggest that the alphavbeta5 integrin plays a critical role in the trafficking of exogenous antigen by immature DCs in this cross-priming pathway.

Efficient interaction of HIV-1 with purified dendritic cells via multiple chemokine coreceptors.

HIV-1 actively replicates in dendritic cell (DC)-T cell cocultures, but it has been difficult to demonstrate substantial infection of purified mature DCs. We now find that HIV-1 begins reverse transcription much more efficiently in DCs than T cells, even though T cells have higher levels of CD4 and gp120 binding. DCs isolated from skin or from blood precursors behave similarly. Several M-tropic strains and the T-tropic strain IIIB enter DCs efficiently, as assessed by the progressive formation of the early products of reverse transcription after a 90-min virus pulse at 37 degrees C. However, few late gag-containing sequences are detected, so that active viral replication does not occur. The formation of these early transcripts seems to follow entry of HIV-1, rather than binding of virions that contain viral DNA. Early transcripts are scarce if DCs are exposed to virus on ice for 4 h, or for 90 min at 37 degrees C, conditions which allow virus binding. Also the early transcripts once formed are insensitive to trypsin. The entry of a M-tropic isolates is blocked by the chemokine RANTES, and the entry of IIIB by SDF-1. RANTES interacts with CCR5 and SDF-1 with CXCR4 receptors. Entry of M-tropic but not T-tropic virus is ablated in DCs from individuals who lack a functional CCR5 receptor. DCs express more CCR5 and CXCR4 mRNA than T cells. Therefore, while HIV-1 does not replicate efficiently in mature DCs, viral entry can be active and can be blocked by chemokines that act on known receptors for M- and T-tropic virus.