Utilizing a High-Fidelity COVID-19 Simulation to Develop Collaboration Skills Among Multispecialty Cohorts

ABSTRACT

Nursing students rarely have the opportunity to witness nurse-to-nurse collaboration with nurses from differing specialties. Simulation can provide students with an opportunity to practice this important skill. In this simulation, students from a critical care course and students from a maternal/newborn course worked together to care for a pregnant client with COVID-19. The client's condition required expertise from both an obstetrical nurse and a critical care nurse. Although the design of the simulation was aimed at collaboration, various other important observations and teaching moments were uncovered during the implementation of the simulation.

Prevalence of Immunomodulator Use as Combination Therapy With Vedolizumab or Ustekinumab in Inflammatory Bowel Disease

INTRODUCTION

The benefit of adding an immunomodulator to vedolizumab and ustekinumab remains unclear and may compromise the safety of these biologics. We evaluated the prevalence and predictors of immunomodulator use with vedolizumab or ustekinumab in patients with inflammatory bowel disease in a large longitudinal cohort.

METHODS

Clinical information was ascertained from electronic medical records of patients enrolled in TARGET-IBD, a prospective longitudinal observational cohort of patients with inflammatory bowel disease (IBD) at 34 sites. The prevalence of immunomodulator use with vedolizumab, ustekinumab, and antitumor necrosis factor therapies and predictors of immunomodulator use with vedolizumab and ustekinumab were estimated. Rates of combination therapy were additionally stratified by time from drug approval.

RESULTS

Four thousand thirty-nine adults with IBD were identified, of whom 18.8% were treated with vedolizumab and 13.0% were treated with ustekinumab. Combination therapy with vedolizumab and ustekinumab exceeded 30% (30.7% and 36.2%, respectively) and was more likely in those with perianal disease or previous biologic exposure. Age and presence of extraintestinal manifestations did not consistently predict the use of an immunomodulator. Combination therapy decreased in the years after drug approval.

DISCUSSION

Combination therapy with vedolizumab or ustekinumab was common and was associated with perianal disease and greater exposure to other biologics, although the practice is decreasing with time. Further data are needed to determine the efficacy and safety of combination therapy in patients initiating vedolizumab or ustekinumab for IBD.

Prevalence and burden of atopic dermatitis involving the head, neck, face, and hand: A cross sectional study from the TARGET-DERM AD cohort

BACKGROUND

Atopic dermatitis (AD) is severely burdensome, and there has been poor characterization of any differences in impact based on the area affected.

OBJECTIVE

To estimate the prevalence and HRQoL impact of head/face/neck/hand (HFNH) involvement among patients with moderate-to-severe atopic dermatitis.

METHODS

All TARGET-DERM AD registry patients with moderate/severe Investigator Global Assessment (vIGA-AD) were assessed using the Patient Oriented SCORing Atopic Dermatitis, Patient Oriented Eczema Measure (POEM) and the (Children's) Dermatology Life Quality Index ((C)DLQI).

RESULTS

541 participants met the criteria (75.0% adults) and 84% (N = 453) reported HFNH involvement. HFNH and non-HFNH involved participants had similar characteristics; 55.2% female and 46.9% White. Compared to the non-HFNH involved, the involved had severe vIGA-AD (28.5% vs 16.3%, P = .02) and higher median body surface area affected (15% vs 10%, P ≤ .01) and were twice as likely to have higher (C)DLQI and POEM scores.

LIMITATIONS

This was an analysis of real-world and patient reported outcome data.

CONCLUSION

Real-world HFNH involved AD patients were associated with significantly worse quality of life, POEM/(C)DLQI, and more severe disease. Detailed assessments of specific areas affected by AD are needed to personalize treatment.

Effectiveness of Remdesivir Treatment Protocols Among Patients Hospitalized with COVID-19: A Target Trial Emulation

BACKGROUND

Remdesivir is recommended for certain hospitalized patients with COVID-19. However, these recommendations are based on evidence from small randomized trials, early observational studies, or expert opinion. Further investigation is needed to better inform treatment guidelines with regard to the effectiveness of remdesivir among these patients.

METHODS

We emulated a randomized target trial using chargemaster data from 333 US hospitals from 1 May 2020 to 31 December 2021. We compared three treatment protocols: remdesivir within 2 days of hospital admission, no remdesivir within the first 2 days of admission, and no remdesivir ever. We used baseline comorbidities recorded from encounters up to 12 months before admission and identified the use of in-hospital medications, procedures, and oxygen supplementation from charges. We estimated the cumulative incidence of mortality or mechanical ventilation/extracorporeal membrane oxygenation with an inverse probability of censoring weighted estimator. We conducted analyses in the total population as well as in subgroups stratified by level of oxygen supplementation.

RESULTS

A total of 274,319 adult patients met the eligibility criteria for the study. Thirty-day in-hospital mortality risk differences for patients adhering to the early remdesivir protocol were -3.1% (95% confidence interval = -3.5%, -2.7%) compared to no early remdesivir and -3.7% (95% confidence interval -4.2%, -3.2%) compared to never remdesivir, with the strongest effect in patients needing high-flow oxygen. For mechanical ventilation/extracorporeal membrane oxygenation, risk differences were minimal.

CONCLUSIONS

We estimate that, among hospitalized patients with COVID-19, remdesivir treatment within 2 days of admission reduced 30-day in-hospital mortality, particularly for patients receiving supplemental oxygen on the day of admission.

Older Adult Patients Use More Aminosalicylate Monotherapy Compared With Younger Patients With Inflammatory Bowel Disease: TARGET-IBD

GOAL

The goal of this study was to describe medication utilization patterns in older inflammatory bowel disease (IBD) patients.

BACKGROUND

Despite a growing population of older patients with Crohn's disease (CD) and ulcerative colitis (UC), questions remain regarding medication utilization patterns in comparison to younger populations.

MATERIALS AND METHODS

We collected data from the 34 sites in TARGET-IBD, a multicenter, observational cohort. The primary outcome in this study was the IBD-specific therapy utilized among older patients with IBD compared with younger age groups. Therapy use was analyzed using pairwise comparisons and then the odds of IBD-specific therapy use among patients older than age 65 were evaluated using multivariable logistic regression models.

RESULTS

We identified 2980 patients with IBD (61% CD). In multivariable analysis, younger patients with UC were significantly less likely to utilize aminosalicylate monotherapy when compared with patients above 65 years [age 18 to 29: adjusted odds ratio (aOR)=0.51, 95% confidence interval (CI): 0.33-0.78]. In patients with CD, younger patients were significantly less likely to use aminosalicylate monotherapy when compared with patients above 65 (greatest difference age 18 to 29: aOR=0.31, 95% CI: 0.18-0.52). Younger patients with CD and UC were significantly more likely to use anti-tumor necrosis factor monotherapy than patients above 65 years (age 18 to 29: aOR=3.87, 95% CI: 2.47-6.06 and aOR=2.68, 95% CI: 1.29-5.58, respectively).

CONCLUSIONS

Older patients with IBD demonstrate significant differences in medication utilization, including more aminosalicylate monotherapy and less anti-tumor necrosis factor monotherapy compared with younger age groups. Given the aging population in the United States, these utilization patterns may have long-term implications for disease control.

Objective disease activity assessment and therapeutic drug monitoring prior to biologic therapy changes in routine inflammatory bowel disease clinical practice: TARGET-IBD

Background

Inflammatory bowel disease (IBD) treatment paradigms recommend objective disease activity assessment and reactive therapeutic drug monitoring (TDM) prior to changes in biologic therapy. We aimed to describe objective marker and TDM assessment in routine clinical practice prior to biologic therapeutic changes in adult IBD patients.

Methods

TARGET-IBD is a prospective longitudinal cohort of over 2100 IBD patients receiving usual care at 34 US academic or community centers enrolled between June 2017 and October 2019 who received biologic therapy and had a dose change or biologic discontinuation for lack of efficacy. Objective markers of disease activity within 12 weeks prior included fecal calprotectin, C-reactive protein (CRP), endoscopy, computed tomography (CT) and magnetic resonance imaging (MRI). TDM data for infliximab or adalimumab was obtained.

Results

525 patients (71.4% Crohn’s disease [CD], 28.6% ulcerative colitis [UC]) receiving biologic therapy underwent dose change (55.6%) or discontinuation (44.4%) for lack of efficacy. The majority were Caucasian (85.7%), 18–39 years old (52.2%), privately insured (81.5%), and at academic centers (73.7%). For dose changes, 67.5% had at least one objective disease activity assessment or TDM in the 12 weeks prior (CD 67.9%, UC 66.2%; P = 0.79). The most common objective marker was CRP in both CD (39.1%) and UC (54.5%). CRP and calprotectin were used significantly more in UC (P = 0.02 and P = 0.03). TDM was obtained in 30.7% (28.8% UC, 31.4% CD; P = 0.72) prior to dose change. For biologic discontinuation, 79.4% patients underwent objective assessment or TDM prior. In CD, CRP (46.3%) was most common, and CT (P = 0.03) and MRI (P < 0.001) were significantly more frequent than in UC. TDM was performed in 40.1% of patients (43.5% UC, 38.0% CD, P = 0.49) prior to discontinuation. Among all participants with dose change or discontinuation, endoscopy was performed in 29.3% with CD and 31.3% with UC. Academic care setting was associated with objective assessment before therapy change (OR 1.59, 95% CI 1.01–2.50).

Conclusion

Nearly one-third of patients undergoing a biologic dose change or discontinuation do not undergo objective disease activity assessment or TDM. Assessment choice differs by disease. Future studies assessing the impact of such practices on long-term outcomes are needed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02143-x.

Patient Characteristics and Outcomes of 11 721 Patients With Coronavirus Disease 2019 (COVID-19) Hospitalized Across the United States

BACKGROUND

As COVID-19 disseminates throughout the US, a better understanding of patient characteristics associated with hospitalization, morbidity and mortality in diverse geographic regions is essential.

METHODS

Hospital chargemaster data on adult patients with COVID-19 admitted to 245 hospitals across 38 states between February 15 and April 20, 2020 were assessed. Clinical course from admission through hospitalization to discharge or death was analyzed.

RESULTS

A total of 11,721 patients were included (majority were >60 years of age [59.9%] and male [53.4%]). Comorbidities included hypertension (46.7%), diabetes (27.8%), cardiovascular disease (18.6%), obesity (16.1%), and chronic kidney disease (12.2%). Mechanical ventilation was required by 1,967 patients (16.8%). Mortality among hospitalized patients was 21.4% and increased to 70.5% among those on mechanical ventilation. Male sex, older age, obesity, geographic region, and the presence of chronic kidney disease or preexisting cardiovascular disease were associated with an increased odds of mechanical ventilation. All aforementioned risk factors, with the exception of obesity, were associated with an increased odds of death (all p& 0.001). Many patients received investigational medications for treatment of COVID-19, including 48 patients on remdesivir and 4,232 on hydroxychloroquine.

CONCLUSION

This large observational cohort describes the clinical course and identifies factors associated with outcomes of hospitalized patients with COVID-19 across the US. These data can inform strategies to prioritize prevention and treatment for this disease.

Factors Associated With Readmission in the United States Following Hospitalization With Coronavirus Disease 2019

BACKGROUND

Patients hospitalized for coronavirus disease 2019 (COVID-19) may experience complications following hospitalization and require readmission. In this analysis, we estimated the rate and risk factors associated with COVID-19-related readmission and inpatient mortality.

METHODS

In this retrospective cohort study, we used deidentified chargemaster data from 297 hospitals across 40 US states on patients hospitalized with COVID-19 from 15 February 2020 through 9 June 2020. Demographics, comorbidities, acute conditions, and clinical characteristics of first hospitalization are summarized. Multivariable logistic regression was used to measure risk factor associations with 30-day readmission and in-hospital mortality.

RESULTS

Among 29 659 patients, 1070 (3.6%) were readmitted. Readmitted patients were more likely to have diabetes, hypertension, cardiovascular disease (CVD), or chronic kidney disease (CKD) vs those not readmitted (P < .0001) and to present on first admission with acute kidney injury (15.6% vs 9.2%), congestive heart failure (6.4% vs 2.4%), or cardiomyopathy (2.1% vs 0.8%) (P < .0001). Higher odds of readmission were observed in patients aged >60 vs 18-40 years (odds ratio [OR], 1.92; 95% confidence interval [CI], 1.48-2.50) and those admitted in the Northeast vs West (OR, 1.43; 95% CI, 1.14-1.79) or South (OR, 1.28; 95% CI, 1.11-1.49). Comorbidities including diabetes (OR, 1.34; 95% CI, 1.12-1.60), CVD (OR, 1.46; 95% CI, 1.23-1.72), CKD stage 1-5 (OR, 1.51; 95% CI, 1.25-1.81), and CKD stage 5 (OR, 2.27; 95% CI, 1.81-2.86) were associated with higher odds of readmission; 12.3% of readmitted patients died during second hospitalization.

CONCLUSIONS

Among this large US population of patients hospitalized with COVID-19, readmission was associated with certain comorbidities and acute conditions during first hospitalization. These findings may inform strategies to mitigate risks of readmission due to COVID-19 complications.

Methodology and Initial Results From a Real-World Observational Cohort of Patients With Inflammatory Bowel Disease: TARGET-IBD

Background

Data on care patterns for inflammatory bowel disease (IBD) from large-scale, diverse clinical cohorts in real-world practice are sparse. We developed a real-world cohort of patients receiving care at academic and community sites, for comparative study of therapies and natural history of IBD.

Methods

We describe novel methodology of central abstraction of clinical data into a real-world IBD registry with patient reported outcomes (PROs). Baseline demographics, clinical characteristics, healthcare utilization, and disease metrics were assessed. Bivariate statistics were used to compare demographic and clinical data by Crohn disease (CD) or ulcerative colitis (UC) and site of care (academic, community).

Results

In 1 year, 1343 IBD patients (60.1% CD, 38.9% UC) were recruited from 27 academic (49.5%) and community (50.5%) sites, exceeding expectations (110% enrolled). Most participants also consented to provide PROs (59.5%) or biosamples (85.7%). Overall, 48.7% of the cohort provided a baseline PRO, and 62.6% provided a biosample. Compared to UC, CD subjects had higher prior (34.1% CD vs 7.7% UC; P < 0.001) and current (72.1% vs 47.9%; P < 0.001) biologic utilization. CD participants from academic sites had more complicated disease than those from community sites (62.5% vs 46.8% stricturing/penetrating; 33.5% vs 27% perianal; 36.8% vs 14.5% prior biologic, respectively). Nearly all (90.4%) participants had endoscopic data of whom 37.7% were in remission. One-year retention was 98.4%.

Conclusions

Centralized data abstraction and electronic PRO capture provided efficient recruitment into a large real-world observational cohort. This novel platform provides a resource for clinical outcomes and comparative effectiveness research in IBD.

International observational atopic dermatitis cohort to follow natural history and treatment course: TARGET-DERM AD study design and rationale

INTRODUCTION

As new topical and systemic treatments become available for atopic dermatitis (AD), there is a need to understand how treatments are being used in routine clinical practice, their comparative effectiveness and their long-term safety in diverse clinical settings.

METHODS AND ANALYSIS

The TARGET-DERM AD cohort is a longitudinal, observational study of patients with AD of all ages, designed to provide practical information on long-term effectiveness and safety unobtainable in traditional registration trials. Patients with physician-diagnosed AD receiving prescription treatment (topical or systemic) will be enrolled at academic and community clinical centres. Up to 3 years of retrospective medical records, 5 years of prospective medical records, and optional biological samples and patient-reported outcomes will be collected. The primary aims include characterisation of AD treatment regimens, evaluation of response to therapy, and description of adverse events.

ETHICS AND DISSEMINATION

TARGET-DERM has been approved by a central IRB (Copernicus Group IRB, 5000 Centregreen Way Suite 200, Cary, North Carolina 27513) as well as local and institutional IRBs. No additional Ethics Committee reviews. Results will be reviewed by a publications committee and submitted to peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT03661866, pre-results.

Mathematical models of dorsal closure

Dorsal closure is a model cell sheet movement that occurs midway through Drosophila embryogenesis. A dorsal hole, filled with amnioserosa, closes through the dorsalward elongation of lateral epidermal cell sheets. Closure requires contributions from 5 distinct tissues and well over 140 genes (see Mortensen et al., 2018, reviewed in Kiehart et al., 2017 and Hayes and Solon, 2017). In spite of this biological complexity, the movements (kinematics) of closure are geometrically simple at tissue, and in certain cases, at cellular scales. This simplicity has made closure the target of a number of mathematical models that seek to explain and quantify the processes that underlie closure's kinematics. The first (purely kinematic) modeling approach recapitulated well the time-evolving geometry of closure even though the underlying physical principles were not known. Almost all subsequent models delve into the forces of closure (i.e. the dynamics of closure). Models assign elastic, contractile and viscous forces which impact tissue and/or cell mechanics. They write rate equations which relate the forces to one another and to other variables, including those which represent geometric, kinematic, and or signaling characteristics. The time evolution of the variables is obtained by computing the solution of the model's system of equations, with optimized model parameters. The basis of the equations range from the phenomenological to biophysical first principles. We review various models and present their contribution to our understanding of the molecular mechanisms and biophysics of closure. Models of closure will contribute to our understanding of similar movements that characterize vertebrate morphogenesis.

A real-world observational cohort of patients with primary biliary cholangitis: TARGET-primary biliary cholangitis study design and rationale

Primary biliary cholangitis (PBC) is a rare chronic cholestatic liver disease that may progress to biliary cirrhosis if left untreated. The first‐line therapy for PBC is ursodeoxycholic acid (UDCA). Unfortunately, 1 of 3 patients does not respond to UDCA. These patients are at risk for developing clinical events, including cirrhosis, complications of portal hypertension, hepatocellular carcinoma, liver transplant, or death. Recently, the U.S. Food and Drug Administration approved obeticholic acid to be used in certain patients with PBC. Off‐label therapies are also used, and several other therapies are currently under evaluation. Real‐world effectiveness of newly approved and off‐label therapies remains unknown. TARGET‐PBC is a 5‐year, longitudinal, observational study of patients with PBC that will evaluate the effectiveness of clinical practice interventions and provide practical information unobtainable in registration trials. Enrollment will take place at both academic and community sites. In addition to consenting to medical records review, participants will be asked to provide an annual blood sample and complete patient reported outcome surveys at predetermined intervals. Any available liver biopsies will be digitally preserved. Conclusion: Key study outcomes will be the evaluation of the safety and effectiveness of PBC interventions and the assessment of disease progression under real‐world conditions. (Hepatology Communications 2018;2:484‐491)

Pancreatic adenocarcinoma patients with localised chronic severe pancreatitis show an increased number of single beta cells, without alterations in fractional insulin area

AIMS/HYPOTHESIS

Recent histological analysis of pancreases obtained from patients with long-standing type 1 diabetes identified chronic islet inflammation and limited evidence suggestive of beta cell replication. Studies in rodent models also suggest that beta cell replication can be induced by certain inflammatory cytokines and by gastrin. We therefore tested the hypothesis that beta cell replication is observed in non-autoimmune human pancreatic disorders in which localised inflammation or elevated gastrin levels are present.

METHODS

Resected operative pancreatic specimens were obtained from patients diagnosed with primary adenocarcinoma (with or without chronic severe pancreatitis) or gastrinoma. Additional pancreatic tissue was obtained from autopsy control patients. Immunohistochemistry was used to assess fractional insulin area, beta cell number and replication rate and differentiation factors relevant to beta cell development.

RESULTS

Fractional insulin area was similar among groups. Patients with pancreatic adenocarcinoma and localised chronic severe pancreatitis displayed significant increases in the number of single beta cells, as well as increased beta cell replication rate and levels of neurogenic differentiation 1 in islets. Patients with gastrinoma demonstrated significant increases in the number of single beta cells, but the beta cell replication rate and islet differentiation factor levels were similar to those in the control group.

CONCLUSIONS/INTERPRETATION

These findings indicate that chronic severe pancreatic inflammation can be associated with significant effects on beta cell number or replication rate, depending on the distribution of the cells. This information may prove useful for attempts seeking to design therapies aimed at inducing beta cell replication as a means of reversing diabetes.

Anaesthetists should wear gloves--touch sensitivity is improved with a new type of thin glove

BACKGROUND

Sterile gloves should be worn for all invasive procedures. However, loss of touch sensitivity when wearing gloves leads to poor compliance among anaesthetists in the UK. Our aim was to investigate whether new surgical glove types, such as extra-thin or latex-free gloves, offer any advantage in touch sensitivity.

METHODS

The skin-pressure sensibility threshold of the gloved pulp of the dominant index finger was established in 24 anaesthetists using nine self-made modified von Frey hairs. The range of forces generated by nylon monofilaments was evenly distributed between 0.5 and 17 mN. The gloves tested were latex Biogel standard, latex-free Biogel Neotech, and extra-thin latex Ansell microthin surgical gloves. The different glove types were assessed in a counterbalancing algorhithm, the individual was blinded, and the filaments were applied in random order.

RESULTS

The median threshold force to touch was significantly lower for the extra-thin surgical gloves in comparison to the standard latex (P = 0.014) and latex-free gloves (P = 0.001). There was no significant difference between the standard latex and latex-free gloves (P = 0.166).

CONCLUSION

We have demonstrated that wearing extra-thin surgical gloves offers increased touch sensitivity. This may improve dexterity when carrying out delicate invasive procedures. Latex-free surgical gloves performed similar to standard latex gloves. Our findings should encourage more widespread glove use among anaesthetists.

Interobserver reliability between a nurse and anaesthetist of tests used for predicting difficult tracheal intubation

We examined the interobserver reliability, between a nurse and anaesthetist, of five tests used to predict difficult tracheal intubation: mouth opening; thyromental distance; head and neck movement; mandibular luxation; and assessment of oropharyngeal view. For each test, an anaesthetic nurse and a specialist registrar anaesthetist were trained to use a standard method of examination. Most of the tests had either good or very good reliability. Assessment of mouth opening demonstrated only moderate reliability and assessment of oropharyngeal view demonstrated poor reliability. The interobserver reliability estimates between a nurse and an anaesthetist are similar to those previously demonstrated between two anaesthetists.

Recombinant adeno-associated virus-mediated alpha-1 antitrypsin gene therapy prevents type I diabetes in NOD mice

Type I diabetes results from an autoimmune destruction of the insulin-producing pancreatic beta cells. Although the exact immunologic processes underlying this disease are unclear, increasing evidence suggests that immunosuppressive, immunoregulatory and anti-inflammatory agents can interrupt the progression of the disease. Alpha 1 antitrypsin (AAT) is a multifunctional serine proteinase inhibitor (serpin) that also displays a wide range of anti-inflammatory properties. To test the ability of AAT to modulate the development of type I diabetes, we performed a series of investigations involving recombinant adeno-associated virus vector (rAAV)-mediated gene delivery of human alpha-1 antitrypsin (hAAT) to nonobese diabetic (NOD) mice. Recombinant AAV-expressing hAAT (rAAV2-CB-AT) was administered intramuscularly to 4-week-old female NOD mice (1 x 10(10) i.u./mouse). A single injection of this vector reduced the intensity of insulitis, the levels of insulin autoantibodies, and the frequency of overt type I diabetes (30% (3/10) at 32 weeks of age versus 70% (7/10) in controls). Transgene expression at the injection sites was confirmed by immunostaining. Interestingly, antibodies against hAAT were present in a majority of the vector-injected mice and circulating hAAT was undetectable when assessed 10 weeks postinjection. This study suggests a potential therapeutic role for AAT in preventing type I diabetes as well as the ability of AAV gene therapy-based approaches to ameliorate disease effectively.

The influence of esmolol on the dose of propofol required for induction of anaesthesia

Cardiac output may be an important determinant of the induction dose of intravenous anaesthetic. Esmolol is known to reduce cardiac output, and we examined its effect on the propofol dose required for induction of anaesthesia. The size of the effect seen with esmolol was compared with midazolam co-induction. Sixty patients were randomly allocated to placebo (saline), esmolol (1mg x kg(-1) bolus, followed by an infusion at 250 microg x kg(-1)min(-1)) or midazolam (0.04 mg x kg(-1)) groups. Induction of anaesthesia commenced 3 min following the administration of the study drug, using a Diprifusor set to achieve plasma propofol concentrations of 10 microg x ml(-1) at 5 min. The primary end point used was the propofol dose per kg at loss of response to command. The mean (SD) propofol dose for each group was 2.38 (0.48) mg x kg(-1) for placebo, 1.79 (0.36) mg x kg(-1) for esmolol and 1.34 (0.35) mg x kg(-1) for midazolam (all means significantly different; p < 0.0005). We found that predosing with esmolol reduces the propofol requirements for induction of anaesthesia by 25%.

Immunity to adeno-associated virus serotype 2 delivered transgenes imparted by genetic predisposition to autoimmunity

Adeno-associated virus (AAV) is widely considered a promising vector for therapeutic gene delivery. This promise is based on previous studies assessing AAVs safety and toxicity, ability to infect nondividing cells, elicit a limited immune response and provide long-term gene expression. However, we now find that earlier studies underappreciated the degree of AAV immunogenicity as well as the extent to which genetic background, through regulation of immune responsiveness, influences the duration of gene expression and thereby the effectiveness of AAV-mediated gene therapy. We evaluated antibody responses in 12 mouse strains to AAV serotype 2 (AAV2) and AAV2-expressed transgene products including green fluorescent protein (GFP), human alpha1-antitrypsin and murine interleukin-10. As expected, all immunocompetent mice administered AAV2 developed serologic evidence of immune responsiveness to the virus. However, a previously unidentified serologic prozone effect was observed suggesting that the concentrations of anti-AAV2 antibodies may have historically been subject to marked underestimation. Furthermore, strains with genetic predisposition to autoimmunity (eg, NOD, NZW, MRL-lpr) specifically imparted a functionally deleterious immune response to AAV-delivered transgene products. These findings suggest that more thorough studies of anti-AAV immunity should be performed, and that genetic predisposition to autoimmunity should be considered when assessing AAV efficacy and safety in humans.

Prevalence of ROPS--equipped tractors and farm/farmer characteristics

Data were collected on tractor safety status and the prevalence of ROPS as part of the Ohio Farm Family Health and Hazard Surveillance Program (FFHHSP) "walk-around" hazard assessments of cash grain farms in central Ohio. Principal operator (PO) characteristics thought a priori to have a possible association with ROPS utilization included age, education, percent time spent farming, total years in agriculture, and previous training in occupational injury prevention. Farm characteristics of interest were farm size, acres of cropland in use, sales value during the past 12 months, and current number of farm workers. Descriptive and logistic regression analyses were conducted to evaluate potential associations between these factors and ROPS utilization patterns. Of 1,044 tractors encountered on 306 farms, 359 (34.4%) were equipped with ROPS, 29 (9.5%) had nothing but ROPS-equipped tractors, and 117 (38.2%) did not have any ROPS-equipped tractors. The absence/presence of ROPS-equipped tractors in our sample was found to vary by several factors, and over a wide range. Results of invariable logistic regression analyses (excluding the relatively small number of tractors manufactured after 1985) indicated that younger POs with at least a high school education who spent more than half their time working in agriculture, employed three or more workers, had 500 or more acres of total farm land and cropland in use, and had a 12-month sales value exceeding $250,000 were more likely to have at least one ROPS-equipped tractor on their farms. However, time spent farming, number of workers, and the 12-month sales value were not strongly predictive in multivariable models. Although more than 20% of the POs in our sample reported having had training in occupational injury prevention, this factor had essentially no value in predicting the absence/presence of ROPS-equipped tractors on their farms. The results of this study illustrate the need for interventions to encourage ROPS retrofitting that target POs with less education and who work on smaller and less productive farms. However, the low overall ROPS utilization rates suggest that all farmers could benefit from intervention efforts.

Pre-operative screening: criteria for referring to anaesthetists

Nurses assess patients pre-operatively using screening questionnaires and locally-developed protocols. Our objectives were to determine which questions might identify patients who should be seen by an anaesthetist before the day of surgery. A review of the literature and a preliminary questionnaire to establish questions to be tested was followed by a modified, two-round Delphi questionnaire to determine the level of agreement by anaesthetists. There was agreement for referring patients who gave a positive response to questions that query: restricted exercise tolerance; previous anaesthetic problems; family history of anaesthetic problem; pathology affecting neck movement; angina; arrhythmia; heart failure; asthma; epilepsy; insulin-dependent diabetes mellitus; liver disease and unspecified kidney disease. There was equivocal agreement on questions that report a myocardial infarction over one year ago, cerebrovascular accident, non insulin-dependent diabetes mellitus and thyroid disease. Nurses should use these criteria during pre-operative assessment to decide the timing of evaluation by an anaesthetist.

Enhancement of survival by LPA via Erk1/Erk2 and PI 3-kinase/Akt pathways in a murine hepatocyte cell line

First published September 5, 2001; 10.1152/ajpcell.00077.2001.-Protective mechanisms for lysophosphatidic acid (LPA) against cell death caused by Clostridium difficile toxin, or tumor necrosis factor-alpha (TNF-alpha) plus D-galactosamine, were investigated in a murine hepatocyte cell line AML12 expressing Edg2 LPA receptor. In these models of hepatocellular injury, LPA prevented hepatocyte damage, suppressed apoptosis, and enhanced cell survival in a dose-dependent fashion. The protective effects of LPA were abolished by wortmannin and LY-294002, specific inhibitors of phosphatidylinositol 3-phosphate kinase (PI 3-kinase), and by PD-98059 and U-0126, inhibitors of MEK1/MEK2. In nontreated hepatocytes, LPA elicited a gradual and sustained increase in phosphorylation of Erk1/Erk2 over 180 min of stimulation and downstream phosphorylation of p90RSK and transcription factor Elk-1. In C. difficile toxin-treated cells, LPA-induced phosphorylation of Erk1/Erk2 was rapid but transient, while p90RSK and Elk-1 phosphorylation did not change significantly. LPA stimulated phosphorylation of Akt in a time-dependent manner in both intact and toxin-treated AML12 hepatocytes. Wortmannin and LY-294002 abolished phosphorylation of Akt, further supporting activation of PI 3-kinase/Akt as a signaling pathway, which mediates hepatocyte protection by LPA. Taken together, these results demonstrate that LPA prevents cell apoptosis induced by C. difficile toxin and TNF-alpha/D-galactosamine in the AML12 murine hepatocyte cell line. Cell protection by LPA involves activation of the mitogen-activated protein kinase Erk1/Erk2 cascade and PI 3-kinase-dependent phosphorylation of Akt.

An adenoviral system for tetracycline-regulated TGF-beta expression mediates a reversible cell cycle arrest

The ability to regulate the proliferation of normal cells in a reversible manner would be a useful adjunct to some clinical therapies. including many types of cancer chemotherapy and surgery for periodontal regeneration. While the application of recombinant growth factors and cytokines to target cells is a logical approach to regulate cell proliferation, the high turnover rates of these peptide factors often make this approach impractical. Recombinant adenoviral vectors can be used to direct the expression of transgene products such as growth factors in many cell types in vitro and in vivo. We have adapted the tetracycline-regulated expression system to allow regulated transforming growth factor (TGF)-beta1 expression using recombinant adenovirus. We demonstrate that infection with a recombinant TGF-beta-encoding virus system in primary human oral keratinocytes and in a lung epithelial cell line is sufficient to allow a cell cycle arrest that is reversible upon tetracycline addition. This inhibition is efficient even after the infection of a minority of cells in a population. These results highlight the possibility of using low level infection with recombinant adenovirus to cause short-term blocks on cell proliferation.

Adeno-associated virus vector-mediated IL-10 gene delivery prevents type 1 diabetes in NOD mice

The development of spontaneous autoimmune diabetes in nonobese diabetic (NOD) mice provides for their use as a model of human type 1 diabetes. To test the feasibility of muscle-directed gene therapy to prevent type 1 diabetes, we developed recombinant adeno-associated virus (rAAV) vectors containing murine cDNAs for immunomodulatory cytokines IL-4 or IL-10. Skeletal muscle transduction of female NOD mice with IL-10, but not IL-4, completely abrogated diabetes. rAAV-IL-10 transduction attenuated the production of insulin autoantibodies, quantitatively reduced pancreatic insulitis, maintained islet insulin content, and altered splenocyte cytokine responses to mitogenic stimulation. The beneficial effects were host specific, as adoptive transfer of splenocytes from rAAV IL-10-treated animals rapidly imparted diabetes in naive hosts, and the cells contained no protective immunomodulatory capacity, as defined through adoptive cotransfer analyses. These results indicate the utility for rAAV, a vector with advantages for therapeutic gene delivery, to transfer immunoregulatory cytokines capable of preventing type 1 diabetes. In addition, these studies provide foundational support for the concept of using immunoregulatory agents delivered by rAAV to modulate a variety of disorders associated with deleterious immune responses, including allergic reactions, transplantation rejection, immunodeficiencies, and autoimmune disorders.

Observed incidence of tumorigenesis in long-term rodent studies of rAAV vectors

Gene therapy using recombinant adeno-associated virus vectors (rAAV) is generally considered safe. During the course of a study designed to determine the long-term efficacy of rAAV-mediated gene therapy initiated in newborn mice with the lysosomal storage disease, mucopolysaccharidosis type VII (MPSVII), a significant incidence of hepatocellular carcinomas and angiosarcomas was discovered. A hepatocellular carcinoma was first detected in a 35-week-old mouse and by 72 weeks of age, three out of five rAAV-treated MPSVII mice had similar lesions. These types of tumors had not been seen previously in long-term studies of MPSVII mice using recombinant enzyme or bone marrow transplantation. In an attempt to ascertain whether mouse strain or GUSB expression confers susceptibility to tumor formation, we histopathologically examined untreated normal mice of the same strain, untreated MPSVII mice, and normal mice overexpressing human GUSB for the presence of tumors and increased hepatocyte replication. The results of these studies do not indicate that MPSVII mice or mice overexpressing human GUSB are susceptible to tumor formation; however, the number of animals examined is too small to draw definitive conclusions. Results from quantitative PCR performed on the tumor samples suggest that the tumors are probably not caused by an insertional mutagenesis event followed by the clonal expansion of a transformed cell. In a separate study, a relatively large group of mice injected with varying doses and types of rAAV vectors had no evidence of hepatic or vascular tumors. Although the mechanism of tumor formation is currently unknown, the tumorigenic potential of rAAV vectors must be rigorously determined in long-term in vivo studies.

Stable therapeutic serum levels of human alpha-1 antitrypsin (AAT) after portal vein injection of recombinant adeno-associated virus (rAAV) vectors

Previous work from our group showed that recombinant adeno-associated virus (rAAV) vectors mediated long-term secretion of therapeutic serum levels of human alpha-1 antitrypsin (hAAT) after a single injection in murine muscle. We hypothesized that hepatocyte transduction could be even more efficient, since these cells represent the natural site of AAT production and secretion. To test this hypothesis, rAAV vectors containing the hAAT cDNA driven by either the human elongation factor 1 alpha promoter, the human cytomegalovirus immediate-early promoter (CMV), or the CMV-chicken beta actin hybrid (CB) promoter were injected into the portal or tail veins of adult C57Bl/6 mice. Potentially therapeutic serum levels of hAAT (600 microg/ml) were achieved after portal vein injection of doses of 4 x 10(9) infectious units (IU), a 10-fold lower dose than that required for similar levels of expression via the i.m. route. Serum levels greater than 1 mg/ml were achieved at doses of 3 x 10(10) IU. Southern blotting of liver DNA revealed the presence of circular episomal vector genomes. Immunostaining showed that transgene expression was scattered throughout the liver parenchyma. Similar results were obtained with a rAAV-CB-green fluorescent protein (GFP) vector. There was no evidence of hepatic toxicity. These data indicate that liver-directed rAAV-based gene therapy is effective in the murine model, and hence might be feasible for treatment of human AAT deficiency.

LPS antagonism reduces graft-versus-host disease and preserves graft-versus-leukemia activity after experimental bone marrow transplantation

Acute graft-versus-host disease (GVHD) and leukemic relapse remain the two major obstacles to successful outcomes after allogeneic bone marrow transplantation (BMT). Recent studies have demonstrated that the loss of gastrointestinal tract integrity, and specifically the translocation of LPS into the systemic circulation, is critical to the induction of cytokine dysregulation that contributes to GVHD. Using a mouse BMT model, we studied the effects of direct LPS antagonism on GVHD severity and graft-versus-leukemia (GVL) activity. Administration of B975, a synthetic lipid-A analogue from day 0 to day +6, reduced serum TNF-alpha levels, decreased intestinal histopathology, and resulted in significantly improved survival and a reduction in clinical GVHD, compared with control-treated animals. Importantly, B975 had no effect on donor T cell responses to host antigens in vivo or in vitro. When mice received lethal doses of P815 tumor cells at the time of BMT, administration of B975 did not impair GVL activity and resulted in significantly improved leukemia-free survival. These findings reveal a critical role for LPS in the early inflammatory events contributing to GVHD and suggest that a new class of pharmacologic agents, LPS antagonists, may help to prevent GVHD while preserving T cell responses to host antigens and GVL activity.

Negotiated safety and other agreements between men in relationships: risk practice redefined

This study examines patterns of agreement, knowledge and practice which can prevent or facilitate HIV transmission among men who are in regular ('primary') male-to-male relationships. Data are from a national volunteer phone-in survey of homosexually-active men in Australia. A sub-sample of 1070 men from a larger sample (n=3039) were found to have one or more regular partners for longer than 6 months. Self-reported HIV serostatus of survey participant and his regular partner, type of agreement regarding anal intercourse both within and outside the regular relationship, and engaging in unprotected anal intercourse with regular and with casual partners were examined. Risk practice was defined as unprotected anal intercourse with a regular partner of different or unknown serostatus and/or unprotected anal intercourse with a casual partner. Agreements were classified as: negotiated safety (28.8%); no unprotected anal intercourse (33.6%); unsafe (10.6%) and no agreement (17.0%). Risk practice was reported by 17.8% of the men. Type of agreement was found to be the strongest predictor of risk practice. Negotiated safety agreements were common, and were kept on the whole. Men with unsafe agreements, although only a small proportion of men in relationships, had high levels of risk practice.

Role of myosin-II phosphorylation in V12Cdc42-mediated disruption of Drosophila cellularization

Microinjection of constitutively active Cdc42 (V12Cdc42) disrupts the actomyosin cytoskeleton during cellularization (Crawford et al., Dev. Biol., 204, 151-164 (1998)). The p21-activated kinase (PAK) family of Ser/Thr kinases are effectors of GTP-bound forms of the small GTPases, Cdc42 and Rac. Drosophila PAK, which colocalizes with actin and myosin-II during cellularization, concentrates at sites of V12Cdc42-induced actomyosin disruption. In vitro biochemical analyses demonstrate that PAK phosphorylates the regulatory light chain (RLC) of Drosophila nonmuscle myosin-II on Ser21, a site known to activate myosin-II function. Although activated PAK does not disrupt the actomyosin cytoskeleton, it induces increased levels of Ser21 phosphorylated RLC. These findings suggest that increased levels of RLC phosphorylation do not contribute to disruption of the actomyosin hexagonal array.

Hyporesponsiveness of donor cells to lipopolysaccharide stimulation reduces the severity of experimental idiopathic pneumonia syndrome: potential role for a gut-lung axis of inflammation

Idiopathic pneumonia syndrome (IPS) is a major complication of allogeneic bone marrow transplantation (BMT). We have shown that experimental IPS is associated with increased levels of LPS and TNF-alpha in the bronchoalveolar lavage (BAL) fluid. We hypothesized that the deleterious effects of these inflammatory mediators in the lung may be linked to gut injury that develops after BMT. To test this hypothesis, we used mouse strains that differ in their sensitivity to LPS as donors in an experimental BMT model. Lethally irradiated C3FeB6F(1) hosts received BMT from either LPS-sensitive or LPS-resistant donors. Five weeks after BMT, LPS-resistant BMT recipients had significantly less lung injury compared with recipients of LPS-sensitive BMT. This effect was associated with reductions in TNF-alpha secretion (both in vitro and in vivo), BAL fluid LPS levels, and intestinal injury. The relationship between TNF-alpha, gut toxicity, and lung injury was examined further by direct cytokine blockade in vivo; systemic neutralization of TNF-alpha resulted in a significant reduction in gut histopathology, BAL fluid LPS levels, and pulmonary dysfunction compared with control-treated animals. We conclude that donor resistance to endotoxin reduces IPS in this model by decreasing the translocation of LPS across the intestinal border and systemic and pulmonary TNF-alpha production. These data demonstrate a potential etiologic link between gut and lung damage after BMT and suggest that methods that reduce inflammatory responses to LPS, and specifically, those that protect the integrity of the gut mucosa, may be effective in reducing IPS after BMT.

Reduced susceptibility of nonobese diabetic mice to TNF-alpha and D-galactosamine-mediated hepatocellular apoptosis and lethality

Nonobese diabetic (NOD/LtJ or NOD) mice are resistant to doses of LPS and D-galactosamine that uniformly produce lethality in C57BL/6J (B6) mice (p < 0.01). Liver caspase-3-like activity, serum transaminase levels (both p < 0.05), and the numbers of apoptotic liver nuclei were also reduced in NOD compared with B6 mice treated with LPS (100 ng) and D-galactosamine (8 mg). NOD mice were also at least 100-fold more resistant to recombinant human TNF-alpha and D-galactosamine treatment than B6 mice (p < 0.001). Binding of recombinant human TNF-alpha to splenocytes from NOD mice was similar to that seen in B6 mice, suggesting that the defect in responsiveness was not due to an inability of recombinant human TNF-alpha to bind the NOD TNF type 1 (p55) receptor. Because the TNF type 1 (p55) receptor shares a common signaling pathway with Fas (CD95), NOD and B6 mice were treated with the Fas agonist antibody, Jo-2. Surprisingly, NOD mice were as sensitive as B6 mice to Fas-induced lethality and hepatic injury. In addition, primary hepatocytes isolated from NOD mice and cultured in vitro in the presence of D-galactosamine with or without TNF-alpha were found to be resistant to apoptosis and cytotoxicity when compared with B6 mice. In contrast, Jo-2 treatment produced similar increases in caspase-3 activity and cytotoxicity in primary hepatocytes from NOD and B6 mice. The resistance to LPS- and TNF-alpha-mediated lethality and hepatic injury in D-galactosamine-sensitized NOD mice is apparently due to a post-TNFR binding defect, and independent of signaling pathways shared with Fas.

Endoscopic detection of dysplasia in patients with Barrett's esophagus using light-scattering spectroscopy

BACKGROUND & AIMS

We conducted a study to assess the potential of light-scattering spectroscopy (LSS), which can measure epithelial nuclear enlargement and crowding, for in situ detection of dysplasia in patients with Barrett's esophagus.

METHODS

Consecutive patients with suspected Barrett's esophagus underwent endoscopy and systematic biopsy. Before biopsy, each site was sampled by LSS using a fiberoptic probe. Diffusely reflected white light was spectrally analyzed to obtain the size distribution of cell nuclei in the mucosal layer, from which the percentage of enlarged nuclei and the degree of crowding were determined. Dysplasia was assigned if more than 30% of the nuclei exceeded 10 microm and the histologic findings compared with those of 4 pathologists blinded to the light-scattering assessment. The data were then retrospectively analyzed to further explore the diagnostic potential of LSS.

RESULTS

Seventy-six sites from 13 patients were sampled. All abnormal sites and a random sample of nondysplastic sites were reviewed by the pathologists. The average diagnoses were 4 sites from 4 different patients as high-grade dysplasia (HGD), 8 sites from 5 different patients as low-grade dysplasia (LGD), 12 as indefinite for dysplasia, and 52 as nondysplastic Barrett's. The sensitivity and specificity of LSS for detecting dysplasia (either LGD or HGD) were 90% and 90%, respectively, with all HGD and 87% of LGD sites correctly classified. Decision algorithms using both nuclear enlargement and crowding further improved diagnostic accuracy, and accurately classified samples into the 4 histologic categories.

CONCLUSIONS

LSS can reliably detect LGD and HGD in patients with Barrett's esophagus.

Newcastle disease virus phosphoprotein gene analysis and transcriptional editing in avian cells

Nucleotide sequence was determined for the phosphoprotein (P) gene from 23 Newcastle disease virus (NDV) isolates representing all defined pathotypes with different chronological and geographic origins. Sequence variation, with synonymous substitutions dominating, occurred throughout the P gene. An exception was a conserved central region containing the transcriptional editing site. Four G nucleotide additions were detected in NDV P gene mRNA potentially creating alternative open reading frames. However, only one in-frame stop codon exists with a single G addition among all isolates that would allow for a potential V protein. A second potential stop codon does not exist in the P gene consensus sequence among all isolates with more than one G nucleotide addition at the editing site. This precludes a possible W protein in these isolates. A second potential alternative in-frame start site exists among all isolates that could encode a predicted X protein for NDV. Comparison of the P gene editing sites among the Paramyxovirinae and predicted P gene usage demonstrates that NDV more closely resembles the respiroviruses and morbilliviruses. Phylogenetic analysis of P gene sequences among NDV isolates demonstrates there are two clades of these viruses. One group includes viruses isolated in the US prior to 1970, while a second cluster includes virulent viruses circulating worldwide.

Tumor necrosis factor-alpha neutralization reduces lung injury after experimental allogeneic bone marrow transplantation

BACKGROUND

Idiopathic pneumonia syndrome (IPS) is a frequent and potentially fatal complication of bone marrow transplantation (BMT). We have previously shown that experimental IPS is associated with increased levels of lipopolysaccaride (LPS) and tumor necrosis factor-alpha (TNFalpha) in the bronchoalveolar lavage (BAL) fluid, and that administration of LPS to animals with extensive graft versus host exacerbated underlying lung injury (Blood 1996; 88: 3230).

METHODS

Lethally irradiated CBA mice received BMT from allogeneic (B10.BR) or syngeneic (CBA) donors. The role of TNFalpha in the exacerbation of pulmonary toxicity caused by LPS injection and in the evolution of IPS after allogeneic BMT was examined by neutralizing TNFalpha after BMT using a soluble binding protein (rhTNFR:Fc).

RESULTS

Five weeks after BMT, administration of rhTNFR:Fc dramatically reduced mortality and prevented the exacerbation of lung injury caused by LPS administration. This protective effect was associated with preservation of pulmonary function and with marked reductions of cells, neutrophils, and LPS in the BAL fluid of treated animals. TNFalpha neutralization from week 4 to 6 after allogeneic BMT effectively halted the progression of systemic GVHD and significantly reduced, but did not prevent lung injury that developed during the treatment period.

CONCLUSIONS

We conclude that TNFalpha is central to early LPS induced toxicity in this model and is a significant, but not the exclusive contributor to the development of IPS after allogeneic BMT.

Fas ligand-deficient gld mice are more susceptible to graft-versus-host-disease

BACKGROUND

The Fas/Fas ligand (FasL) pathway plays an important role in a number of apoptotic processes that could be important for the development of graft-versus-host disease (GVHD) after bone marrow transplantation (BMT), such as cytolysis of target cells by cytotoxic T cells, regulation of inflammatory responses, peripheral deletion of autoimmune cells, costimulation of T cells, and activation-induced cell death.

METHODS

To study the role of the Fas/FasL pathway in the complex pathophysiology of graft versus host disease (GVHD), we used FasL-deficient B6.gld mice as recipients in a Major Histocompatibility Antigen Complex-matched minor Histocompatibility Antigen-mismatched murine model for GVHD after allogeneic BMT (C3H.SW-->B6).

RESULTS

We found a significantly higher morbidity and mortality from GVHD compared to control B6 recipients. Histopathological analysis of the GVHD target organs demonstrated that B6.gld recipients developed significantly more thymic and intestinal GVHD. B6gld recipients with GVHD demonstrated an increased expansion of donor T cells and monocytes/ macrophages compared to control B6 recipients, whereas serum TNF-alpha levels were equivalent in B6.gld recipients and control B6 recipients.

CONCLUSION

This study demonstrates that the expression of FasL in the BMT recipient is important for the host's ability to control GVHD.

Neutrophils die in the gingival crevice, periodontal pocket, and oral cavity by necrosis and not apoptosis

BACKGROUND

Neutrophils play important roles in the homeostasis of periodontal tissues. However, remarkably little is known about how these cells live and die in the gingival crevice and periodontal pocket. We have examined whether subgingival neutrophils die by necrosis or apoptosis and have begun to study the mechanisms controlling the functional lifespan of these cells.

METHODS

Neutrophils collected from clinically healthy gingival crevices, periodontal pockets, and the oral cavity (saliva) were examined with Hoechst dye 33342, propidium iodide/eithidium bromide, and FITC-annexin V to identify live, dead, and apoptotic cells. Blood neutrophils were cultured for 17 to 20 hours in the presence or absence of gingival crevice washings (GC-w) to study the effect of GC-w on neutrophil apoptosis. In addition, endotoxin was removed from GC-w by affinity resin to investigate the contribution of LPS to the inhibitory effect of GC-w on blood neutrophils.

RESULTS

The percentage of dead neutrophils in all subgingival sites and in all oral samples far exceeded the percentage of apoptotic neutrophils. In all 3 locations, approximately 30% of neutrophils were dead, whereas less than 1% of neutrophils were apoptotic. We conclude that the majority of neutrophils which lose their viability within gingival crevices, periodontal pockets and the oral cavity die by necrosis and not by apoptosis. Washings obtained from clinically healthy gingival crevices (GC-w) variably, but significantly, delayed apoptosis of peripheral blood neutrophils (mean suppression 45.7% +/- SD 22.3). Removal of endotoxin from GC-w significantly reduced this inhibitory effect.

CONCLUSIONS

Our findings provide insights into the mechanisms of neutrophil death and the control of the functional lifespan of neutrophils in gingival crevices and periodontal pockets and therefore into the pathogenesis of periodontal diseases.

Fas-deficient lpr mice are more susceptible to graft-versus-host disease

The Fas/Fas ligand (FasL) pathway is involved in a variety of regulatory mechanisms that could be important for the development of graft-vs-host disease (GVHD) after bone marrow transplantation (BMT), such as cytolysis of target cells by cytotoxic T cells, regulation of inflammatory responses, peripheral deletion of autoimmune cells, costimulation of T cells, and activation-induced cell death. To further evaluate the role of Fas/FasL in the complex pathophysiology of GVHD, we used Fas-deficient B6.lpr mice as recipients in a MHC-matched minor histocompatibility Ag-mismatched murine model for GVHD after allogeneic BMT (C3H.SW-->B6). We found a significantly higher morbidity and mortality from GVHD compared with control B6 recipients. In contrast, B6.lpr recipients had very little hepatic GVHD, although all other specific GVHD target organs (skin, intestines, and thymus) were more severely affected than in the control B6 recipients. B6.lpr recipients with GVHD demonstrated intact donor lymphoid engraftment and an increase in expansion of donor T cells and monocytes/macrophages compared with control B6 recipients. Serum levels of IFN-gamma and TNF-alpha were higher in B6.lpr recipients than in control B6 recipients, and monocytes/macrophages in B6.lpr recipients appeared more sensitized. B6.lpr recipients had more residual peritoneal macrophages after BMT, and peritoneal macrophages from B6.lpr mice could induce a greater proliferative response from C3H.SW splenocytes. This study demonstrates that the expression of Fas in the recipient is required for GVHD of the liver, but shows unexpected consequences when host tissues lack the expression of Fas for the development of GVHD in other organs and systemic GVHD.

Derivation of hepatocytes from bone marrow cells in mice after radiation-induced myeloablation

Following a report of skeletal muscle regeneration from bone marrow cells, we investigated whether hepatocytes could also derive in vivo from bone marrow cells. A cohort of lethally irradiated B6D2F1 female mice received whole bone marrow transplants from age-matched male donors and were sacrificed at days 1, 3, 5, and 7 and months 2, 4, and 6 posttransplantation (n = 3 for each time point). Additionally, 2 archival female mice of the same strain who had previously been recipients of 200 male fluorescence-activated cell sorter (FACS)-sorted CD34(+)lin(-) cells were sacrificed 8 months posttransplantation under the same protocol. Fluorescence in situ hybridization (FISH) for the Y-chromosome was performed on liver tissue. Y-positive hepatocytes, up to 2.2% of total hepatocytes, were identified in 1 animal at 7 days posttransplantation and in all animals sacrificed 2 months or longer posttransplantation. Simultaneous FISH for the Y-chromosome and albumin messenger RNA (mRNA) confirmed male-derived cells were mature hepatocytes. These animals had received lethal doses of irradiation at the time of bone marrow transplantation, but this induced no overt, histologically demonstrable, acute hepatic injury, including inflammation, necrosis, oval cell proliferation, or scarring. We conclude that hepatocytes can derive from bone marrow cells after irradiation in the absence of severe acute injury. Also, the small subpopulation of CD34(+)lin(-) bone marrow cells is capable of such hepatic engraftment.

Endotoxin-stimulated macrophages decrease bile acid uptake in WIF-B cells, a rat hepatoma hybrid cell line

Endotoxemia leads to cytokine-mediated alterations of the hepatocellular sodium-taurocholate-cotransporting polypeptide (ntcp). We hypothesized that stimulated macrophages are essential transducers for down-regulating hepatocellular bile salt uptake in response to endotoxin (lipopolysaccharide [LPS]) exposure. Using an in vitro model, we exposed mouse macrophages (IC-21 cell line) to LPS for 24 hours. Concentrations of cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-1beta, and IL-6 increased 10.6-fold, 12.5-fold, and 444-fold, respectively, in LPS-conditioned IC-21 medium (CM) versus unconditioned IC-21 medium (UM). WIF-B rat hepatoma hybrid cells were incubated with either CM or UM or treated directly with medium containing recombinant TNF-alpha, IL-1beta, and IL-6. [(3)H]Taurocholate ([(3)H]TC) uptake decreased in WIF-B cells exposed to either TNF-alpha (54% of control), IL-1beta (78%), IL-6 (55%) as single additives, or in triple combination (TCC) (43%). A virtually identical decrease was observed after exposing WIF-B cells to CM (52%, P <.001). LPS had no direct effect on [(3)H]TC uptake. CM treatment did not decrease L-alanine transport in WIF-B cells. Blocking antibodies against TNF-alpha, IL-1beta, and IL-6 restored the diminished [(3)H]TC uptake in cells exposed to TCC and CM to 87% and 107% of controls, respectively. Northern blotting revealed that ntcp messenger RNA (mRNA) expression was significantly reduced in WIF-B cells after exposure to CM, and in primary rat hepatocytes exposed to CM or TNF-alpha (68%, 14%, and 29% of control, respectively). We conclude that macrophages and their ability to secrete the cytokines TNF-alpha, IL-1beta, and IL-6 may be essential in mediating the endotoxin-induced cholestatic effect of decreased hepatocellular bile salt uptake.

Characterization of primary isolate-like variants of simian-human immunodeficiency virus

Several different strains of simian-human immunodeficiency virus (SHIV) that contain the envelope glycoproteins of either T-cell-line-adapted (TCLA) strains or primary isolates of human immunodeficiency virus type 1 (HIV-1) are now available. One of the advantages of these chimeric viruses is their application to studies of HIV-1-specific neutralizing antibodies in preclinical AIDS vaccine studies in nonhuman primates. In this regard, an important consideration is the spectrum of antigenic properties exhibited by the different envelope glycoproteins used for SHIV construction. The antigenic properties of six SHIV variants were characterized here in neutralization assays with recombinant soluble CD4 (rsCD4), monoclonal antibodies, and serum samples from SHIV-infected macaques and HIV-1-infected individuals. Neutralization of SHIV variants HXBc2, KU2, 89.6, and 89.6P by autologous and heterologous sera from SHIV-infected macaques was restricted to an extent that these viruses may be considered heterologous to one another in their major neutralization determinants. Little or no variation was seen in the neutralization determinants on SHIV variants 89.6P, 89.6PD, and SHIV-KB9. Neutralization of SHIV HXBc2 by sera from HXBc2-infected macaques could be blocked with autologous V3-loop peptide; this was less true in the case of SHIV 89.6 and sera from SHIV 89.6-infected macaques. The poorly immunogenic but highly conserved epitope for monoclonal antibody IgG1b12 was a target for neutralization on SHIV variants HXBc2, KU2, and 89.6 but not on 89.6P and KB9. The 2G12 epitope was a target for neutralization on all five SHIV variants. SHIV variants KU2, 89.6, 89.6P, 89.6PD, and KB9 exhibited antigenic properties characteristic of primary isolates by being relatively insensitive to neutralization in peripheral blood mononuclear cells with serum samples from HIV-1-infected individuals and 12-fold to 38-fold less sensitive to inhibition with recombinant soluble CD4 than TCLA strains of HIV-1. The utility of nonhuman primate models in AIDS vaccine development is strengthened by the availability of SHIV variants that are heterologous in their neutralization determinants and exhibit antigenic properties shared with primary isolates.

The canals of Hering and hepatic stem cells in humans

Small, extraportal, hepatic parenchymal cells, positive for biliary-type cytokeratins, may represent hepatic stem cells, canals of Hering (CoH), and/or ductal plate remnants. We evaluated these cells 3 dimensionally in normal human liver and massive necrosis. Tissues from normal human livers and from 1 liver with acetaminophen-induced massive necrosis were serially sectioned, immunostained for cytokeratin 19 (CK19), and sequentially photographed. Images were examined to determine 3-dimensional relationships among CK19-positive cells. Immunostains for other hepatocyte and progenitor cell markers were examined. In normal livers, intraparenchymal CK19-positive cells lined up as linear arrays in sequential levels. One hundred of 106 (94.3%) defined, complete arrays within levels examined, most having 1 terminus at a bile duct, the other in the lobule, beyond the limiting plate. In massive necrosis, there were 767 individual CK19-positive cells or clusters around a single portal tract, 747 (97.4%) of which were spatially related forming arborizing networks connected to the interlobular bile duct by single tributaries. C-kit was positive in normal CoH. CK19 co-expressed with HepPar1, c-kit, and alpha-fetoprotein (AFP) in parenchymal cells in massive necrosis. Small, extraportal, biliary-type parenchymal cells represent cross-sections of the CoH that radiate from the portal tract, usually extending past the limiting plate into the proximate third of the hepatic lobule. The 3-dimensional structure of ductular reactions in massive necrosis suggests that these reactions are proliferations of the cells lining the CoH. Therefore, the CoH consist of, or harbor, facultative hepatic stem cells in humans.

Hepatic toxicity and persistence of ser/thr protein phosphatase inhibition by microcystin in the little skate Raja erinacea

Microcystin-induced ser/thr protein phosphatase (PP) inhibition and toxicity were examined in the little skate (Raja erinacea), an evolutionarily primitive marine vertebrate. As in mammals, PP inhibition and toxicity were exclusively hepatocellular, but were much more persistent in the skate. A dose of 63 microg/kg given iv to adult male skates resulted in the near complete inhibition of hepatic PP activity at 24 h. PP activity was still 95% inhibited 7 days after dosing in skates given 125 microg/kg microcystin. Mortality occurred at doses of 500 microg/kg or more. Hepatic lesions were only seen in animals with fully inhibited PP activity in liver. The histological changes seen at 125 microg/kg were mild periportal inflammatory changes increasing in severity together with hepatocyte necrosis at higher doses of microcystin. Microcystin persisted and could be detected in plasma up to 7 days after dosing. This finding shows that, in the skate, as in mammals, the liver is the only organ capable of uptake of microcystin, since there was no significant inhibition of PP activity in the rectal gland and small decreases in PP activity of the kidney that were not time or dose dependent. In vitro microcystin caused dose-dependent inhibition of PP activity in isolated skate hepatocytes, while it was without effect in cultured rectal glands. Uptake of microcystin and the accompanying inhibition of PP activity in skate hepatocytes was prevented by the addition of a series of organic dyes and bile acids. The spectrum of inhibitors of microcystin uptake in skate is similar to that seen in the rat, indicating common features of the carrier(s) in these diverse species.

Analysis of nucleotides and aromatic amino acids in normal and neoplastic colon mucosa by ultraviolet resonance raman spectroscopy

The objective of this study was to explore the potential of using ultraviolet resonance Raman (UVRR) spectroscopy to analyze normal and neoplastic colon tissue. Ultraviolet light at 251 nm, generated from the third harmonic of a Titanium:Sapphire laser, was used to irradiate the surfaces of surgically resected human colon specimens from six patients, five clinically diagnosed with adenocarcinoma, and one with familial adenomatous polyposis. All grossly neoplastic samples found to contain mucosal dysplasia or invasive adenocarcinoma upon histologic evaluation, were analyzed in parallel with normal tissue obtained from the same specimen and located at least 1 cm away from grossly neoplastic tissue. The colon spectra were modeled as a linear combination of nucleotide, aromatic amino acid, and lipid lineshapes, using chemical standards as a reference. Nucleotide and amino acid contributions to the UVRR spectra were quantified by a least squares minimization method. The least squares minimization spectral model was verified in aqueous solutions, where relative concentrations of free nucleotides and DNA were quantified with < 10% error. Of the 11 neoplastic samples studied from the 6 specimens, 10 showed either a lower amino acid/nucleotide ratio, a lower level of adenyl (A) signal, or both when compared with their normal counterpart. Lower amino acid/nucleotide ratio was present in five of six samples containing only dysplasia, and three of the five samples containing invasive adenocarcinoma. Lower A was present in all five samples containing invasive cancer, and in three of the six samples containing only dysplasia. This lower level of A corroborates previously published biochemistry work showing a lower level of total adenylates in tumor homogenates compared with normal tissue. Our data indicate that surface UVRR may provide unique information about site-to-site changes in cellular metabolites during colon carcinogenesis.