Longitudinal dynamics of infection and serum antibody in A. actinomycetemcomitans periodontitis

OBJECTS: This report describes one of the first prospective studies delineating the relationship between infection, host antibody responses and disease exacerbations and remissions in a distinct subset of periodontitis patients infected with A. actinomycetemcomitans. DESIGN: The design of this longitudinal study included visits for each patient approximately every 2 months for up to 3 years. SUBJECTS AND METHODS: Subjects (n = 51) included 16 adult periodontitis (AP) and 11 early-onset periodontitis (EOP) patients with elevated serum IgG antibody to A. actinomycetemcomitans and infection with this microorganism, 12 AP patients with normal levels of anti-Aa antibody, and 12 normal subjects. MEASUREMENT OUTCOMES: Clinical parameters included a gingival index, plaque index, bleeding on probing, pocket depth, and attachment level. Disease activity was defined as loss of attachment during the monitoring intervals. Serum IgG, IgM and IgA antibody to A. actinomycetemcomitans Y4 (serotype b) was quantit-ated using an ELISA. Subgingival plaque samples were examined for A. actinomycetemcomitans using colony immunobiotting. Human serum IgG antibody specificities to outer membrane antigens (OMA) of A. actinomycetemcomitans Y4 were determined using Western immunoblotting. RESULTS: A. actinomycetemcomitans-infected AP patients had a higher frequency of teeth infected when compared to the EOP patients. However, the EOP patients exhibited a trend for higher levels of A. actinomycetemcomitans in those teeth that were infected. Active disease patients demonstrated a significantly greater frequency of infected sites, as well as significant elevations in the proportions of A. octinomycetemcomitans. Both EOP and AP groups showed significantly elevated IgG, IgM and IgA antibody to A. actinomycetemcornitans when compared to a periodontally normal group. The level of IgG antibody was significantly elevated in A. actinomycetemcomitans-positive patients with active disease, while IgA antibody was decreased in a number of the active group patients. Plaque samples derived from active sites showed a clear and significant increase in A. actinomycetemcomitans that occurred from 2–6 months prior to the identification of disease activity. Approximately 70% of the active disease patients showed an increase in IgG antibody level by 2–4 months prior to disease activity. Studies of the antigen reactivity patterns of serum IgG indicated that antibody to antigens of 65, 58, 48, 29 and 24 kDa were more frequent in patients who showed active disease, while those patients with the greatest frequency of active disease appeared to show a general decrease in the recognition of the A. actinomycetemcomitans OMA. CONCLUSIONS: It appears that A. actinomycetemcomitans infection relates to a particular type of disease with accompanying antibody responses that reflect periods of active disease. The dynamics of A. actinomycetemcomitans infection and the level and specificity of systemic antibody responses to this pathogen support an important contribution of the immune response to managing this infection.     

Genomic insights into abdominal aortic aneurysms

Introduction

An individual’s genetic background plays a significant role in his or her chances of developing an abdominal aortic aneurysm (AAA). This risk is likely to be due to a combination of multiple small effect genetic factors acting together, resulting in considerable difficulty in the identification of these factors.

Methods

Methods for the identification of genetic factors associated with disease are usually based on the analysis of genetic variants in case-control studies. Over the last decade, owing to advances in bioinformatics and laboratory technology, these studies have progressed from focusing on the examination of a single genetic variant in each study to the examination of many millions of variants in a single experiment. We have conducted a series of such experiments using these methods.

Results

Our original methods using candidate gene approaches led to the initial identification of a genetic variant in the interleukin-10 gene associated with AAA. However, further studies failed to confirm this association and highlighted the necessity for adequately powered studies to be conducted, as well as the need for confirmatory studies to be performed, prior to the acceptance of a variant as a risk for disease. The subsequent application of genomic techniques to our sample set, in a global collaboration, has led to the identification of three robustly verified risk loci for AAA in the LRP1, LDLR and SORT1 genes.

Conclusions

Genomic studies of AAA have led to the identification of new pathways involved in the pathogenesis of AAA. The exploration of these pathways has the potential to unlock new avenues for therapeutic intervention to prevent the development and progression of AAA.     

Neuropeptide Y Attenuates Stress‐Induced Bone Loss Through Suppression of Noradrenaline Circuits

Chronic stress and depression have adverse consequences on many organ systems, including the skeleton, but the mechanisms underlying stress‐induced bone loss remain unclear. Here we demonstrate that neuropeptide Y (NPY), centrally and peripherally, plays a critical role in protecting against stress‐induced bone loss. Mice lacking the anxiolytic factor NPY exhibit more anxious behavior and elevated corticosterone levels. Additionally, following a 6‐week restraint, or cold‐stress protocol, Npy‐null mice exhibit three‐fold greater bone loss compared to wild‐type mice, owing to suppression of osteoblast activity. This stress‐protective NPY pathway acts specifically through Y2 receptors. Centrally, Y2 receptors suppress corticotropin‐releasing factor expression and inhibit activation of noradrenergic neurons in the paraventricular nucleus. In the periphery, they act to control noradrenaline release from sympathetic neurons. Specific deletion of arcuate Y2 receptors recapitulates the Npy‐null stress response, coincident with elevated serum noradrenaline. Importantly, specific reintroduction of NPY solely in noradrenergic neurons of otherwise Npy‐null mice blocks the increase in circulating noradrenaline and the stress‐induced bone loss. Thus, NPY protects against excessive stress‐induced bone loss, through Y2 receptor‐mediated modulation of central and peripheral noradrenergic neurons. © 2014 American Society for Bone and Mineral Research.     

Point-of-care testing for coagulation studies in a stroke protocol: a time-saving innovation

Study Objectives

Time counts in thrombolytic therapy for stroke. An international normalized ratio (INR) greater than 1.7 may preclude its use. We studied whether the use of point-of-care testing (POCT) for INR in the emergency department (ED) may substitute for the same test done in the central hospital laboratory, thereby reducing time to treatment.

Methods

We performed a prospective observational study comparing a POCT analysis of INR (i-STAT-1; Abbott Inc, Abbott Park, Ill) with a simultaneously drawn sample sent to the central laboratory. We tested a convenience sample of adult patients taking warfarin who presented to the ED of a tertiary teaching hospital.

Results

Thirty-two patients were enrolled. A receiver operator curve analysis was performed. Sensitivity and specificity were calculated for laboratory INR cutoff of 1.7. The area under the curve was 0.979 (95% confidence interval [CI], 0.843-0.991). When POCT INR was 2.1, the sensitivity for laboratory INR being higher than 1.7 was 100% (CI, 62.9%-100.0%), and the specificity was 90.5 (CI, 69.6-98.5). When POCT INR was 1.8, the specificity for laboratory INR being lower than 1.7 was 100% (CI, 83.7%-100%), and the sensitivity was 62.5% (CI, 24.7%-91.0%). The regression coefficient (r) value was 0.9648.

Conclusion

Correlation of POCT INR with that of the central laboratory and receiver operator curve characteristics are excellent. In general, POCT INR is about 0.3 higher than the laboratory INR. This is not generally of clinical importance, but when using cutoff of 1.7 (central laboratory), it may be. We describe a 3-tiered system for use of POCT INR in determining use of tissue-type plasminogen activator.     

Bone Microenvironment-Suppressed T Cells Increase Osteoclast Formation and Osteolytic Bone Metastases in Mice

Immunotherapies use components of the immune system, such as T cells, to fight cancer cells, and are changing cancer treatment, causing durable responses in some patients. Bone metastases are a debilitating complication in advanced breast and prostate cancer patients. Approved treatments fail to cure bone metastases or increase patient survival and it remains unclear whether immunotherapy could benefit patients. The bone microenvironment combines various immunosuppressive factors, and combined with T cell products could increase bone resorption fueling the vicious cycle of bone metastases. Using syngeneic mouse models, our study revealed that bone metastases from 4T1 breast cancer contain tumor-infiltrating lymphocyte (TILs) and their development is increased in normal mice compared to immunodeficient and T-cell depleted mice. This effect seemed caused by the TILs specifically in bone, because T-cell depletion increased 4T1 orthotopic tumors and did not affect bone metastases from RM-1 prostate cancer cells, which lack TILs. T cells increased osteoclast formation ex vivo and in vivo contributing to bone metastasis vicious cycle. This pro-osteoclastic effect is specific to unactivated T cells, because activated T cells, secreting interferon γ (IFNγ) and interleukin 4 (IL-4), actually suppressed osteoclastogenesis, which could benefit patients. However, non-activated T cells from bone metastases could not be activated in ex vivo cultures. 4T1 bone metastases were associated with an increase of functional polymorphonuclear and monocytic myeloid-derived suppressor cells (MDSCs), potent T-cell suppressors. Although effective in other models, sildenafil and zoledronic acid did not affect MDSCs in bone metastases. Seeking other therapeutic targets, we found that monocytic MDSCs are more potent suppressors than polymorphonuclear MDSCs, expressing programmed cell death receptor-1 ligand (PD-L1)⁺ in bone, which could trigger T-cell suppression because 70% express its receptor, programmed cell death receptor-1 (PD-1). Collectively, our findings identified a new mechanism by which suppressed T cells increase osteoclastogenesis and bone metastases. Our results also provide a rationale for using immunotherapy because T-cell activation would increase their anti-cancer and their anti-osteoclastic properties. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).     

Queer diagnoses revisited: The past and future of homosexuality and gender diagnoses in DSM and ICD

The American Psychiatric Association (APA) recently completed a several year process of revising the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). During that time, there were objections raised to retaining DSM's gender identity disorder diagnoses and calls to remove them, just as homosexuality had been removed from DSM-II in 1973. At the conclusion of the DSM-5 revision process, the gender diagnoses were retained, albeit in altered form and bearing the new name of ‘gender dysphoria’. The author of this paper was a member of the DSM-5 Workgroup on Sexual and Gender Identity Disorders and presently serves on the WHO Working Group on Sexual Disorders and Sexual Health. Both groups faced similar tasks: reconciling patients’ needs for access to care with the stigma of being given a psychiatric diagnosis. The differing nature of the two diagnostic manuals led to two different outcomes. As background, this paper updates the history of homosexuality and the gender diagnoses in the DSM and in the International Statistical Classification of Diseases and Related Health Problems (ICD) as well as what is expected to happen to the homosexuality and gender diagnoses following the current ICD-11 revision process.     

Interkingdom assemblages in human saliva display group-level surface mobility and disease-promoting emergent functions

Fungi and bacteria often engage in complex interactions, such as the formation of multicellular biofilms within the human body. Knowledge about how interkingdom biofilms initiate and coalesce into higher-level communities and which functions the different species carry out during biofilm formation remain limited. We found native-state assemblages of Candida albicans (fungi) and Streptococcus mutans (bacteria) with highly structured arrangement in saliva from diseased patients with childhood tooth decay. Further analyses revealed that bacterial clusters are attached within a network of fungal yeasts, hyphae, and exopolysaccharides, which bind to surfaces as a preassembled cell group. The interkingdom assemblages exhibit emergent functions, including enhanced surface colonization and growth rate, stronger tolerance to antimicrobials, and improved shear resistance, compared to either species alone. Notably, we discovered that the interkingdom assemblages display a unique form of migratory spatial mobility that enables fast spreading of biofilms across surfaces and causes enhanced, more extensive tooth decay. Using mutants, selective inactivation of species, and selective matrix removal, we demonstrate that the enhanced stress resistance and surface mobility arise from the exopolymeric matrix and require the presence of both species in the assemblage. The mobility is directed by fungal filamentation as hyphae extend and contact the surface, lifting the assemblage with a “forward-leaping motion.” Bacterial cell clusters can “hitchhike” on this mobile unit while continuously growing, to spread across the surface three-dimensionally and merge with other assemblages, promoting community expansion. Together, our results reveal an interkingdom assemblage in human saliva that behaves like a supraorganism, with disease-causing emergent functionalities that cannot be achieved without coassembly.

The microbial life on Earth often resides on surfaces, where cells form multicellular structures known as biofilms (1). Extensive efforts have been devoted to understanding the biofilm formation process and the mechanisms underlying the biofilm lifestyle (1–3). While most studies have focused on bacteria, eukaryotic microbes also frequently form biofilms. Furthermore, previous studies have revealed that biofilms composed of bacteria and fungi are highly abundant in nature, establishing complex interkingdom interactions (4–7). Such bacterial–fungal biofilms can display enhanced virulence and survival, which is achieved through tight cell–cell cohesion, metabolite exchange, and extracellular polymeric matrices within established communities (4–6). How interkingdom biofilms initiate and develop on the surface, and which functions the different species carry out during this process, remains unclear.In the human oral cavity, biofilms formed by bacteria and fungi have a major impact on health (7, 8). For example, patients affected by severe childhood caries (tooth decay), a widespread and costly infectious disease affecting toddlers worldwide (9), display high carriage of the bacterium Streptococcus mutans and the fungus Candida albicans, both in saliva and in biofilms formed on teeth (dental plaque) (10). Previous studies have shown that these distinct microbes form interkingdom biofilms with enhanced virulence under sugar-rich conditions (11, 12). However, interactions of these two species in saliva have not been characterized, and the extent to which the interactions between S. mutans and C. albicans influence the dynamics of biofilm formation and its functional properties is unknown.In this study, we investigated the interactions between S. mutans and C. albicans during colonization and biofilm formation in human saliva, and made several unexpected discoveries with implications for disease. We observed that in saliva of toddlers affected by severe tooth decay, S. mutans and C. albicans formed highly structured interkingdom assemblages. Using real-time multiscale imaging and computational analysis, we studied the organization of such interkingdom assemblages and assessed their role during biofilm formation spatiotemporally. These experiments showed that bacterial clusters attached to yeast and hyphal complexes to form assemblages that display emergent properties, including enhanced surface colonization, a higher growth rate, and a stronger tolerance to shear stress and antimicrobials, which are not observed in either bacteria or fungi alone. Surprisingly, when individually tracked, these interkingdom assemblages display a unique mode of migratory group-level mobility, enabled by fungal filamentation across surfaces, which is used by the attached bacterial clusters for “hitchhiking.” Through this mobility, the interkingdom assemblages rapidly proliferate across the surface and expand three-dimensionally, leading to biofilm superstructures and extensive enamel decay on ex vivo tooth surfaces that cannot be achieved by each species alone. Hence, our data reveal an interkingdom assemblage found in human saliva that efficiently colonizes, displays emergent properties, and enhances surface spreading through a group-level mobility mechanism that propels clusters of otherwise nonmotile bacteria and fungi across the surface, to ultimately promote community spatial expansion and disease-causing activity.     

Towards evidence-based practice in medical training: making evaluations more meaningful

CONTEXT: The evaluation of training is problematic and the evidence base inconclusive. This situation may arise for 2 main reasons: training is not understood as a complex intervention and, related to this, the evaluation methods applied are often overly simplistic. METHOD: This paper makes the case for construing training, especially in the field of specialist medical education, as a complex intervention. It also selectively reviews the available literature in order to match evaluative techniques with the demonstrated complexity. CONCLUSIONS: Construing training as a complex intervention can provide a framework for selecting the most appropriate methodology to evaluate a given training intervention and to appraise the evidence base for training fairly, choosing from among both quantitative and qualitative approaches and applying measurement at multiple levels of training impact.     

Wallerian degeneration after cerebral infarction: evaluation with sequential MR imaging

The dynamic signal intensity changes at magnetic resonance (MR) imaging in active and chronic wallerian degeneration in the corticospinal tract were evaluated. Forty-three patients with wallerian degeneration seen on MR images after cerebral infarction were studied. When possible, patients with acute stroke were examined with MR imaging prospectively at the onset of symptoms and then at weekly intervals for several months. Focal infarction without distal axonal degeneration is demonstrated for the 1st month following onset of clinical symptoms. At 4 weeks, a well-defined band of hypointense signal appears on T2-weighted images in the topographic distribution of the corticospinal tract. After 10-14 weeks, the signal becomes permanently hyperintense. Over several years, accompanying ipsilateral brain stem shrinkage occurs. The dark signal intensity observed on T2-weighted images between 4 and 14 weeks is believed to result primarily from transitory increased lipid-protein ratio.