Predictive Models for Very Preterm Birth: Developing a Point-of-Care Tool.

OBJECTIVE: The objective of this study was to create three point-of-care predictive models for very preterm birth using variables available at three different time points: prior to pregnancy, at the end of the first trimester, and mid-pregnancy. STUDY DESIGN: This is a retrospective cohort study of 359,396 Ohio Medicaid mothers from 2008 to 2015. The last baby for each mother was included in the final dataset. Births prior to 22 weeks were excluded. Multivariable logistic regression was used to create three models. These models were validated on a cohort that was set aside and not part of the model development. The main outcome measure was birth prior to 32 weeks. RESULTS: The final dataset contained 359,396 live births with 6,516 (1.81%) very preterm births. All models had excellent calibration. Goodness-of-fit tests suggested strong agreement between the probabilities estimated by the model and the actual outcome experience in the data. The mid-pregnancy model had acceptable discrimination with an area under the receiver operator characteristic curve of approximately 0.75 in both the developmental and validation datasets. CONCLUSION: Using data from a large Ohio Medicaid cohort we developed point-of-care predictive models that could be used before pregnancy, after the first trimester, and in mid-pregnancy to estimate the probability of very preterm birth. Future work is needed to determine how the calculator could be used to target interventions to prevent very preterm birth. KEY POINTS: · We developed predictive models for very preterm birth.. · All models showed excellent calibration.. · The models were integrated into a risk calculator..

Development of a Deep Learning Network to Classify Inferior Vena Cava Collapse to Predict Fluid Responsiveness.

OBJECTIVES: To create a deep learning algorithm capable of video classification, using a long short-term memory (LSTM) network, to analyze collapsibility of the inferior vena cava (IVC) to predict fluid responsiveness in critically ill patients. METHODS: We used a data set of IVC ultrasound (US) videos to train the LSTM network. The data set was created from IVC US videos of spontaneously breathing critically ill patients undergoing intravenous fluid resuscitation as part of 2 prior prospective studies. We randomly selected 90% of the IVC videos to train the LSTM network and 10% of the videos to test the LSTM network's ability to predict fluid responsiveness. Fluid responsiveness was defined as a greater than 10% increase in the cardiac index after a 500-mL fluid bolus, as measured by bioreactance. RESULTS: We analyzed 211 videos from 175 critically ill patients: 191 to train the LSTM network and 20 to test it. Using standard data augmentation techniques, we increased our sample size from 191 to 3820 videos. Of the 175 patients, 91 (52%) were fluid responders. The LSTM network was able to predict fluid responsiveness moderately well, with an area under the receiver operating characteristic curve of 0.70 (95% confidence interval [CI], 0.43-1.00), a positive likelihood ratio of infinity, and a negative likelihood ratio of 0.3 (95% CI, 0.12-0.77). In comparison, point-of-care US experts using video review offline and manual diameter measurement via software caliper tools achieved an area under the receiver operating characteristic curve of 0.94 (95% CI, 0.83-0.99). CONCLUSIONS: We demonstrated that an LSTM network can be trained by using videos of IVC US to classify IVC collapse to predict fluid responsiveness. Our LSTM network performed moderately well given the small training cohort but worse than point-of-care US experts. Further training and testing of the LSTM network with a larger data sets is warranted.

A single center retrospective cohort study comparing low-molecular-weight heparins to direct oral anticoagulants for the treatment of venous thromboembolism in patients with cancer - A real world experience.

INTRODUCTION: Low-molecular-weight heparins are the standard treatment for cancer-associated thrombosis. Recently, direct oral anticoagulants are a new option for thrombosis treatment; however, data supporting the use of direct oral anticoagulants for cancer-associated thrombosis are limited. OBJECTIVES: The primary objective of this study was to determine the rate of recurrent cancer-associated thrombosis and major bleeding within 6 months of starting either low-molecular-weight heparin or direct oral anticoagulant for treatment of cancer-associated thrombosis. Secondary objectives were to determine the rates of clinically relevant-non-major bleeding and all-cause mortality. PATIENTS/METHODS: This is a retrospective cohort study including adults with cancer-associated thrombosis treated with low-molecular-weight heparin or direct oral anticoagulant between 2010 and 2016 at the Ohio State University. Medical records were reviewed for 6 months after initiation of anticoagulation or until the occurrence of recurrent cancer-associated thrombosis, major bleeding, cessation of anticoagulation of interest, or death, whichever occurred first. RESULTS: Four hundred and eighty patients were included (290 low-molecular-weight heparin and 190 direct oral anticoagulant). Patients treated with direct oral anticoagulant were found to carry "lower risk" features including cancer with lower VTE risk and lower rate of metastatic disease. After adjustment for baseline differences, there was no significant difference in the rate of recurrent cancer-associated thrombosis (7.2% low-molecular-weight heparin vs 6.3% direct oral anticoagulant, p = 0.71) or major bleeding (7.6% low-molecular-weight heparin vs 2.6% direct oral anticoagulant, p = 0.08). CONCLUSIONS: Our study demonstrates that in a select population of cancer patients with VTE, direct oral anticoagulant use can be as effective and safe compared to the standard therapy with low-molecular-weight heparin.

Unusual behaviour induced by phase separation in hydrogel microspheres.

Hydrogel microspheres with the capability to interact with charged species such as various drugs by ion-exchange processes are useful in a variety of biomedical applications. Such systems have been developed to allow active loading of the microsphere with chemotherapeutic agents in the hospital pharmacy for subsequent locoregional therapy of tumours in the liver by drug-eluting bead chemoembolization (DEB-TACE). A variety of microspherical embolisation systems have been described, all based upon hydrogels bearing anionic functionalities to allow interaction with cationically charged drugs. We have recently prepared a series of microspheres bearing cationic functionality and have observed some unusual behaviour induced by phase-separation that occurs during the synthesis of the microspheres. The phase-separation results in the core of the microsphere being enriched in cationic polymer component compared to the outer polyvinyl alcohol (PVA)-based phase. For certain formulations, subsequent swelling in water results in the PVA-rich skins separating from the charged cores. Ion-exchange interactions with model compounds bearing multi-anionic groups create differential contraction of the charged core relative to the skin, resulting in an unusual "golf-ball" appearance to the surface of the microspheres. STATEMENT OF SIGNIFICANCE: The authors believe that the unusual behaviour of the microspheres reported in this paper is the first observation of its kind resulting from phase-separation during synthesis. This could have novel applications in drug delivery for systems that can respond by shedding their skin or altering the surface area to volume ratio upon loading a drug.

Transforming growth factor ß recruits persistent MAPK signaling to regulate long-term memory consolidation in Aplysia californica.

In this study, we explore the mechanistic relationship between growth factor signaling and kinase activity that supports the protein synthesis-dependent phase of long-term memory (LTM) consolidation for sensitization ofAplysia Specifically, we examine LTM for tail shock-induced sensitization of the tail-elicited siphon withdrawal (T-SW) reflex, a form of memory that requires both (i) extracellular signal-regulated kinase (ERK1/2; MAPK) activity within identified sensory neurons (SNs) that mediate the T-SW and (ii) the activation of transforming growth factor ß (TGFß) signaling. We now report that repeated tail shocks that induce intermediate-term (ITM) and LTM for sensitization, also induce a sustained post-training phase of MAPK activity in SNs (lasting at least 1 h). We identified two mechanistically distinct phases of post-training MAPK: (i) an immediate phase that does not require ongoing protein synthesis or TGFß signaling, and (ii) a sustained phase that requires both protein synthesis and extracellular TGFß signaling. We find that LTM consolidation requires sustained MAPK, and is disrupted by inhibitors of protein synthesis and TGFß signaling during the consolidation window. These results provide strong evidence that TGFß signaling sustains MAPK activity as an essential mechanistic step for LTM consolidation.

Reelin protects against amyloid ß toxicity in vivo.

Alzheimer's disease (AD) is a currently incurable neurodegenerative disorder and is the most common form of dementia in people over the age of 65 years. The predominant genetic risk factor for AD is the ε4 allele encoding apolipoprotein E (ApoE4). The secreted glycoprotein Reelin enhances synaptic plasticity by binding to the multifunctional ApoE receptors apolipoprotein E receptor 2 (Apoer2) and very low density lipoprotein receptor (Vldlr). We have previously shown that the presence of ApoE4 renders neurons unresponsive to Reelin by impairing the recycling of the receptors, thereby decreasing its protective effects against amyloid ß (Aß) oligomer-induced synaptic toxicity in vitro. We showed that when Reelin was knocked out in adult mice, these mice behaved normally without overt learning or memory deficits. However, they were strikingly sensitive to amyloid-induced synaptic suppression and had profound memory and learning disabilities with very low amounts of amyloid deposition. Our findings highlight the physiological importance of Reelin in protecting the brain against Aß-induced synaptic dysfunction and memory impairment.

Distinct Growth Factor Families Are Recruited in Unique Spatiotemporal Domains during Long-Term Memory Formation in Aplysia californica.

Several growth factors (GFs) have been implicated in long-term memory (LTM), but no single GF can support all of the plastic changes that occur during memory formation. Because GFs engage highly convergent signaling cascades that often mediate similar functional outcomes, the relative contribution of any particular GF to LTM is difficult to ascertain. To explore this question, we determined the unique contribution of distinct GF families (signaling via TrkB and TGF-ßr-II) to LTM formation in Aplysia. We demonstrate that TrkB and TGF-ßr-II signaling are differentially recruited during two-trial training in both time (by trial 1 or 2, respectively) and space (in distinct subcellular compartments). These GFs independently regulate MAPK activation and synergistically regulate gene expression. We also show that trial 1 TrkB and trial 2 TGF-ßr-II signaling are required for LTM formation. These data support the view that GFs engaged in LTM formation are interactive components of a complex molecular network.

Latent memory facilitates relearning through molecular signaling mechanisms that are distinct from original learning.

A highly conserved feature of memory is that it can exist in a latent, non-expressed state which is revealed during subsequent learning by its ability to significantly facilitate (savings) or inhibit (latent inhibition) subsequent memory formation. Despite the ubiquitous nature of latent memory, the mechanistic nature of the latent memory trace and its ability to influence subsequent learning remains unclear. The model organism Aplysia californica provides the unique opportunity to make strong links between behavior and underlying cellular and molecular mechanisms. Using Aplysia, we have studied the mechanisms of savings due to latent memory for a prior, forgotten experience. We previously reported savings in the induction of three distinct temporal domains of memory: short-term (10min), intermediate-term (2h) and long-term (24h). Here we report that savings memory formation utilizes molecular signaling pathways that are distinct from original learning: whereas the induction of both original intermediate- and long-term memory in naïve animals requires mitogen activated protein kinase (MAPK) activation and ongoing protein synthesis, 2h savings memory is not disrupted by inhibitors of MAPK or protein synthesis, and 24h savings memory is not dependent on MAPK activation. Collectively, these findings reveal that during forgetting, latent memory for the original experience can facilitate relearning through molecular signaling mechanisms that are distinct from original learning.

More than cholesterol transporters: lipoprotein receptors in CNS function and neurodegeneration.

Members of the low-density lipoprotein (LDL) receptor gene family have a diverse set of biological functions that transcend lipid metabolism. Lipoprotein receptors have broad effects in both the developing and adult brain and participate in synapse development, cargo trafficking, and signal transduction. In addition, several family members play key roles in Alzheimer's disease (AD) pathogenesis and neurodegeneration. This Review summarizes our current understanding of the role lipoprotein receptors play in CNS function and AD pathology, with a special emphasis on amyloid-independent roles in endocytosis and synaptic dysfunction.

Overcoming dose limitations using the orbital(®) multi-breath dry powder inhaler.

PURPOSE: A new approach to delivering high doses of dry powder medicaments to the lung is presented. The Orbital(®) dry powder device is designed to deliver high doses of drugs to the respiratory tract in a single dosing unit, via multiple inhalation maneuvers, overcoming the need to prime or insert multiple capsules. METHODS: The Orbital was tested in its prototype configuration and compared with a conventional RS01 capsule device. Three formulations were evaluated: 200 mg of spray-dried ciprofloxacin formulation for respiratory infection, 200 mg of spray-dried mannitol formulation for mucus clearance, and 100, 200, and 400 mg of co-spray-dried 1:8 formulations containing ciprofloxacin and mannitol as combination therapy. The systems were evaluated in terms of physicochemical properties and tested using a multistage liquid impinger at 60 L/min. Emptying rates were evaluated, and the aerosolization performance compared with 10 capsules used sequentially in the RS01. RESULTS AND DISCUSSION: The systems were different in terms of morphology, thermal response, moisture sorption, and stability; however, they had similar sizes when measured by laser diffraction, making them suitable for comparison in the Orbital and RS01 devices. The aerosolization performance from the Orbital device and RS01 was dependent on the formulation type; however, the fine particle fraction (FPF) produced by the Orbital device was higher than that by the RS01. The FPFs for ciprofloxacin, mannitol, and co-spray-dried formulation were 67.1±1.8, 47.1±2.2, and 42.0±1.8, respectively. For the Orbital, 90% of the loaded dose was delivered within 10 inhalation maneuvers, with the profile being dependent on the formulation type. CONCLUSION: The Orbital provides a means of delivering high doses of medicine to the respiratory tract through multiple breath maneuvers after a single actuation. This approach will allow the delivery of a wide range of high-payload formulations (>100 mg) for the treatment of a variety of lung disorders. To date, no such passive device exists that meets these crucial criteria.

Pattern and predictability in memory formation: from molecular mechanisms to clinical relevance.

Most long-term memories are formed as a consequence of multiple experiences. The temporal spacing of these experiences is of considerable importance: experiences distributed over time (spaced training) are more easily encoded and remembered than either closely spaced experiences, or a single prolonged experience (massed training). In this article, we first review findings from studies in animal model systems that examine the cellular and molecular properties of the neurons and circuits in the brain that underlie training pattern sensitivity during long-term memory (LTM) formation. We next focus on recent findings which have begun to elucidate the mechanisms that support inter-trial interactions during the induction of LTM. Finally, we consider the implications of these findings for developing therapeutic strategies to address questions of direct clinical relevance.

MAPK establishes a molecular context that defines effective training patterns for long-term memory formation.

Although the importance of spaced training trials in the formation of long-term memory (LTM) is widely appreciated, surprisingly little is known about the molecular mechanisms that support interactions between individual trials. The intertrial dynamics of ERK/MAPK activation have recently been correlated with effective training patterns for LTM. However, whether and how MAPK is required to mediate intertrial interactions remains unknown. Using a novel two-trial training pattern which induces LTM in Aplysia, we show that the first of two training trials recruits delayed protein synthesis-dependent nuclear MAPK activity that establishes a unique molecular context involving the recruitment of CREB kinase and ApC/EBP and is an essential intertrial signaling mechanism for LTM induction. These findings provide the first demonstration of a requirement for MAPK in the intertrial interactions during memory formation and suggest that the kinetics of MAPK activation following individual experiences determines effective training intervals for LTM formation.

Bleeding risk factors associated with argatroban therapy in the critically ill.

Argatroban is a parenteral direct thrombin inhibitor labeled for anticoagulation in patients with confirmed or suspected heparin-induced thrombocytopenia in the United States. Currently there are no studies evaluating bleeding risk factors in Intensive Care Unit patients.To determine bleeding risk factors associated with argatroban therapy in the critically ill. Critically ill patients admitted between July 2007-June 2008 who received argatroban were included in this retrospective cohort study. The primary endpoint was the incidence of bleeding complications associated with argatroban. Major bleeding was defined as a hemoglobin reduction ≥2 g/dL plus a transfusion of ≥2 units of blood in a 24 h period, or a retroperitoneal, intracranial, prosthetic joint, or other life-threatening bleed. Minor bleeding was any overt bleeding not fitting the major bleeding definition. Secondary outcomes included identifying risk factors for bleeding. Seventy-three patients were included with 16 (21.9%) total bleeding complications, 7 (9.6%) major and 9 (12.3%) minor bleeds. Four risk factors for bleeding were identified by univariate analysis: major surgery prior to or during argatroban therapy (OR = 8.4, 95% CI: 2.3-30.1, p = 0.001), dosing weight >90 kg (OR = 4.8, 95% CI: 1.4-15.8, p = 0.01), total bilirubin >3 mg/dL (OR = 8.1, 95% CI: 2.1-31.1, p = 0.002), and baseline platelets ≤70 K/µL (OR = 4.2, 95 % CI: 1.1-16.3, p = 0.039).Risks and benefits of argatroban should be weighed in patients with major surgery prior to or during argatroban, dosing weight ≥90 kg, total bilirubin ≥3 mg/dL, and baseline platelets ≤70 K/µL.

The association between body mass index, processes of care, and outcomes from mechanical ventilation: a prospective cohort study.

OBJECTIVE: To determine the association between excess weight and processes of care and outcomes for critically ill adults. DESIGN: Prospective cohort study. SETTING: Three medical intensive care units at two hospitals. PATIENTS: Five hundred eighty mechanically ventilated adult patients admitted between February 1, 2006 and January 31, 2008. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: After adjusting weight based on the recorded fluid balance before enrollment, 21.9% of subjects were categorized into different body mass index categories than without this adjustment. We used a competing risk analysis with events of interest considered death during hospitalization and successful liberation from mechanical ventilation. We found no statistically significant difference between body mass index categories (<25 kg/m² vs. 25 to <30 kg/m² vs. ≥30 kg/m²) in the competing risks analyses when the results were unadjusted or adjusted for severity of illness and comorbidities. When the analyses were adjusted for the use of continuous infusions of opioids and/or sedatives and ventilator parameters (tidal volume per ideal body weight, positive end-expiratory pressure, and airway pressure), subjects with an overweight fluid-balance-adjusted body mass index had significantly lower hazard ratios for dying while hospitalized (adjusted hazard ratio 0.68 [95% confidence interval 0.47-0.99], p=.044), and those with an obese fluid-adjusted body mass index had significantly higher hazard ratios for successful extubation (adjusted hazard ratio 1.53 [95% confidence interval 1.14-2.06], p=.005). An analysis of longer-term mortality found lower adjusted hazard ratios for subjects with overweight (adjusted hazard ratio 0.74 [95% confidence interval 0.56-0.96]) and obese (adjusted hazard ratio 0.74 [95% confidence interval 0.59-0.94]) fluid-balance-adjusted body mass indices. CONCLUSIONS: Processes of provided care may affect the observed association between excess weight and outcomes for critically ill adults and should be considered when making inferences about observed results. It is unknown if disparities in processes of care are due to clinically justified reasons for variation, bias against heavier patients, or other reasons.

The tail-elicited tail withdrawal reflex of Aplysia is mediated centrally at tail sensory-motor synapses and exhibits sensitization across multiple temporal domains.

The defensive withdrawal reflexes of Aplysia californica have provided powerful behavioral systems for studying the cellular and molecular basis of memory formation. Among these reflexes the tail-elicited tail withdrawal reflex (T-TWR) has been especially useful. In vitro studies examining the monosynaptic circuit for the T-TWR, the tail sensory-motor (SN-MN) synapses, have identified the induction requirements and molecular basis of different temporal phases of synaptic facilitation that underlie sensitization in this system. They have also permitted more recent studies elucidating the role of synaptic and nuclear signaling during synaptic facilitation. Here we report the development of a novel, compartmentalized semi-intact T-TWR preparation that allows examination of the unique contributions of processing in the SN somatic compartment (the pleural ganglion) and the SN-MN synaptic compartment (the pedal ganglion) during the induction of sensitization. Using this preparation we find that the T-TWR is mediated entirely by central connections in the synaptic compartment. Moreover, the reflex is stably expressed for at least 24 h, and can be modified by tail shocks that induce sensitization across multiple temporal domains, as well as direct application of the modulatory neurotransmitter serotonin. This preparation now provides an experimentally powerful system in which to directly examine the unique and combined roles of synaptic and nuclear signaling in different temporal domains of memory formation.

Vocal cord dysfunction: beyond severe asthma.

BACKGROUND: Vocal cord dysfunction (VCD) is the abnormal adduction of the vocal cords during inspiration causing extrathoracic airway obstruction. VCD has been described as a confounder of severe asthma. The influence of VCD among less severe asthmatics has not been previously defined. METHODS: We retrospectively reviewed the medical records of 59 patients with pulmonologist-diagnosed asthma who were referred for videolaryngostroboscopy (VLS) testing from 2006 to 2007. RESULTS: A total of 44 patients had both asthma and VCD. 15 patients had asthma without concomitant VCD. Females were predominant in both groups. Overall, the majority of patients referred for VLS testing had mild-to-moderate asthma (78%) and 72% of these patients had VCD. Few patients from either group had "classic" VCD symptoms of stridor or hoarseness. Gastroesophageal reflux disease (GERD) and rhinitis were common in both groups. CONCLUSIONS: Vocal cord dysfunction occurs across the spectrum of asthma severity. There was a lack of previously described "classic" VCD symptoms among asthmatics. Symptoms were diverse and not easily distinguished from common symptoms of asthma, highlighting the need for a high index of suspicion for VCD in patients with asthma. Failure to consider and diagnose VCD may result in misleading assumptions about asthma control, and result in unnecessary adjustments of asthma medications. The high prevalence of GERD raises the question of the role of acid reflux in the pathogenesis of VCD in asthmatics.

It's all about timing.

In the formation of long-term memories, a "spaced" distribution of study sessions is more beneficial than closely spaced "massed" study sessions. Pagani et al. (2009) examine the molecular basis of this spacing effect in Drosophila and find a role for the SHP2 homolog, corkscrew, an activator of Ras/MAPK signaling, in establishing optimal spacing intervals.

The clinical utility of eucapnic voluntary hyperventilation testing for the diagnosis of exercise-induced bronchospasm.

BACKGROUND: Exercise-induced bronchospasm (EIB) is the acute, transient airway narrowing associated with exercise. Eucapnic voluntary hyperventilation (EVH) has been used to diagnose EIB in elite athletes and in research settings. The clinical utility of EVH in a general pulmonary practice has not previously been reported. Thus we sought to determine the utility and applicability of EVH testing in the clinical setting. METHODS: We retrospectively analyzed 178 EVH tests performed at the Ohio State University Medical Center. RESULTS: A total of 178 EVH studies were performed. Fifty patients (28%) were EIB-positive. A threshold of 60% of the predicted maximum voluntary ventilation (MVV) per minute was used as a criterion for an adequate EVH test. A majority of patients, 127 (71%), had adequate EVH tests. Females were less likely to achieve 60% MVV than males (80% vs. 55%; p = 0.002). Of the 51 patients with inadequate tests, 17 (33%) were EIB-positive; 16 of these 17 were female. Overall, EVH testing was diagnostic in 144 of 178 (81%) of patients tested. CONCLUSIONS: We present the first description of the clinical use of EVH testing for the diagnosis of EIB in a large pulmonary practice. EVH was diagnostic in a large majority of patients. EVH is an excellent and feasible modality to diagnose EIB in patients seen in a general pulmonary practice. Our data highlight the need for further studies regarding the appropriate minimum threshold minute ventilation for an EVH test and to explain potential mechanisms for seemingly different stimulus thresholds for bronchospasm in males versus females.

Transient mitogen-activated protein kinase activation is confined to a narrow temporal window required for the induction of two-trial long-term memory in Aplysia.

Although it is commonly appreciated that spaced training is superior to massed training in memory formation, the molecular mechanisms underlying this feature of memory are largely unknown. We previously described the selective benefit of multiple spaced (vs massed) training trials in the induction of long-term memory (LTM) for sensitization in Aplysia californica. We now report that LTM can be induced with only two spaced training trials [tail shocks (TSs)] when the second TS is administered 45 min after the first. In contrast, spacing intervals of 15 and 60 min are ineffective. This surprisingly narrow permissive training window for two-trial LTM is accompanied by an equally narrow window of transient mitogen-activated protein kinase (MAPK) activation, a necessary signaling molecule for LTM induction, at 45 min after a single TS. Thus, the transient recruitment of MAPK following a single TS may provide a narrow molecular window for two-trial LTM formation.

Immune competence of cancer-reactive T cells generated de novo in adult tumor-bearing mice.

The impact of timing of antigen introduction into fetus and neonates leads to the suggestion that pre-existing antigens are tolerogenic to immunocompetent cells generated thereafter. This hypothesis predicts that in patients with cancer who are undergoing bone marrow transplantation, newly produced T cells with specificity for pre-existing tumor cells will be inactivated by the tumor antigens in the host. Because the effect of tumor cells on developing cancer-reactive T cells has not been investigated, we set out to systematically analyze the impact of tumor cells in the periphery on the development of tumor-reactive T cells in the thymus and their immunocompetence in the periphery. Our data demonstrate that in the host in which a tumor is established in the periphery, the cancer-reactive T cells develop normally, remain fully immunocompetent, become activated in the periphery, and cause regression of large established tumors. The immunocompetence of T cells generated in an antigen-bearing host is also confirmed in a skin graft transplantation model.