An in vivo method for diversifying the functions of therapeutic antibodies.

V(D)J recombination generates mature B cells that express huge repertoires of primary antibodies as diverse immunoglobulin (Ig) heavy chain (IgH) and light chain (IgL) of their B cell antigen receptors (BCRs). Cognate antigen binding to BCR variable region domains activates B cells into the germinal center (GC) reaction in which somatic hypermutation (SHM) modifies primary variable region-encoding sequences, with subsequent selection for mutations that improve antigen-binding affinity, ultimately leading to antibody affinity maturation. Based on these principles, we developed a humanized mouse model approach to diversify an anti-PD1 therapeutic antibody and allow isolation of variants with novel properties. In this approach, component Ig gene segments of the anti-PD1 antibody underwent de novo V(D)J recombination to diversify the anti-PD1 antibody in the primary antibody repertoire in the mouse models. Immunization of these mouse models further modified the anti-PD1 antibodies through SHM. Known anti-PD1 antibodies block interaction of PD1 with its ligands to alleviate PD1-mediated T cell suppression, thereby boosting antitumor T cell responses. By diversifying one such anti-PD1 antibody, we derived many anti-PD1 antibodies, including anti-PD1 antibodies with the opposite activity of enhancing PD1/ligand interaction. Such antibodies theoretically might suppress deleterious T cell activities in autoimmune diseases. The approach we describe should be generally applicable for diversifying other therapeutic antibodies.

Interleukin-6 produced by enteric neurons regulates the number and phenotype of microbe-responsive regulatory T cells in the gut.

The immune and enteric nervous (ENS) systems monitor the frontier with commensal and pathogenic microbes in the colon. We investigated whether FoxP3+ regulatory T (Treg) cells functionally interact with the ENS. Indeed, microbe-responsive RORγ+ and Helios+ subsets localized in close apposition to nitrergic and peptidergic nerve fibers in the colon lamina propria (LP). Enteric neurons inhibited in vitro Treg (iTreg) differentiation in a cell-contact-independent manner. A screen of neuron-secreted factors revealed a role for interleukin-6 (IL-6) in modulating iTreg formation and their RORγ+ proportion. Colonization of germfree mice with commensals, especially RORγ+ Treg inducers, broadly diminished colon neuronal density. Closing the triangle, conditional ablation of IL-6 in neurons increased total Treg cells but decreased the RORγ+ subset, as did depletion of two ENS neurotransmitters. Our findings suggest a regulatory circuit wherein microbial signals condition neuronal density and activation, thus tuning Treg cell generation and immunological tolerance in the gut.

Conditional antibody expression to avoid central B cell deletion in humanized HIV-1 vaccine mouse models.

HIV-1 vaccine development aims to elicit broadly neutralizing antibodies (bnAbs) against diverse viral strains. In some HIV-1-infected individuals, bnAbs evolved from precursor antibodies through affinity maturation. To induce bnAbs, a vaccine must mediate a similar antibody maturation process. One way to test a vaccine is to immunize mouse models that express human bnAb precursors and assess whether the vaccine can convert precursor antibodies into bnAbs. A major problem with such mouse models is that bnAb expression often hinders B cell development. Such developmental blocks may be attributed to the unusual properties of bnAb variable regions, such as poly-reactivity and long antigen-binding loops, which are usually under negative selection during primary B cell development. To address this problem, we devised a method to circumvent such B cell developmental blocks by expressing bnAbs conditionally in mature B cells. We validated this method by expressing the unmutated common ancestor (UCA) of the human VRC26 bnAb in transgenic mice. Constitutive expression of the VRC26UCA led to developmental arrest of B cell progenitors in bone marrow; poly-reactivity of the VRC26UCA and poor pairing of the VRC26UCA heavy chain with the mouse surrogate light chain may contribute to this phenotype. The conditional expression strategy bypassed the impediment to VRC26UCA B cell development, enabling the expression of VRC26UCA in mature B cells. This approach should be generally applicable for expressing other bnAbs that are under negative selection during B cell development.

An examination of neurocognition and symptoms as predictors of post-hospital community tenure in treatment resistant schizophrenia.

Neurocognition and psychopathology are robust predictors of community functioning and relapse/rehospitalization in schizophrenia. Existing studies are however limited because they have ignored the most chronic, treatment-resistant patients. Moreover, the prediction of functional outcomes has yet to be extended to the duration of community tenure, an indicator of the capacity of chronically-hospitalized patients to gain traction in the community. The current study examined neurocognition and symptom severity at discharge as potential predictors of community tenure in chronically-hospitalized treatment-resistant patients. The study recruited 90 people with treatment-resistant schizophrenia who received services on an inpatient unit. Participants completed measures of psychopathology and neurocognition prior to discharge. Following discharge, participants were tracked at current residences six months and one year post-discharge to assess community tenure. The percentage of individuals who continued to live in the community at 12-month follow-up was 51%. Severe negative symptoms but not neurocognitive impairment or positive symptoms was a significant predictor of shorter post-hospital community tenure. Of the negative symptoms domain, anhedonia-asociality proved to be the most relevant predictor of community tenure in the sample. The capacity to elicit goal-directed behaviors in response to anticipated physical and social rewards may be an important treatment target for sustaining community tenure.

Incidence of Adjacent Segment Disease Requiring Reoperation After Lumbar Laminectomy Without Fusion: A Study of 398 Patients.

BACKGROUND: Adjacent segment disease (ASD) has not been described after laminectomy without fusion. OBJECTIVE: To determine the incidence of ASD after a 1- or 2-level lumbar laminectomy. METHODS: We retrospectively reviewed medical records of all patients who underwent 1- or 2-level, bilateral lumbar laminectomy without fusion for degenerative spinal disease (all follow-up ≥1 year). ASD was defined as clinical and/or radiographic evidence of degenerative spinal disease that required reoperation at the level above or below the index laminectomy. RESULTS: Of the 398 patients, the incidence of ASD requiring reoperation was 10%. The 39 ASD cases were almost equally distributed at L2-L3 (31%), L3-L4 (26%), and L5-S1 (31%), and to a lesser extent at L4-L5 (15%) (P = .51). The ASD incidences of 10% and 9% were equivalent after a 1- and 2-level laminectomy, respectively (P = .76). Rostral ASD was statistically more common than caudal ASD after both the 1- (P < .001) and 2- (P < .001) level laminectomy. Of the 39 ASD cases, 95% required laminectomy, 26% discectomy, and 49% fusion. Average time to ASD was 4 years. After a Kaplan-Meier analysis, time to reoperation for ASD was equivalent among the 1- and 2-level laminectomy cohorts (log-rank test, P = .13). CONCLUSION: The cumulative incidence of ASD requiring reoperation was 10% over a mean of 4 years. Both the 1- and 2-level laminectomy cohorts experienced equivalent incidences and rates of ASD. Of the 39 operations for ASD, about half required a fusion.

Impact of Age on Short-term Outcomes After Lumbar Fusion: An Analysis of 1395 Patients Stratified by Decade Cohorts.

BACKGROUND: The safety and efficacy of spinal fusion in the elderly population remains uncertain with conflicting data. OBJECTIVE: To determine if elderly patients undergoing instrumented lumbar fusion have increased 30-day complication rates compared to younger patients. METHODS: The American College of Surgeons National Surgical Quality Improvement Program was used to identify all patients undergoing instrumented posterolateral lumbar fusion between 2005 and 2011. Patients were stratified by decade cohorts as follows: <65, 65 to 75, 75 to 85, and ≥85 years old. All 30-day complications were grouped as overall composite morbidity and were compared using multivariate analysis. RESULTS: A total of 1395 patients were identified and the overall 30-day complication rate was 11.47%. The complication rates were 9.04% and 14.05% for patients younger than 65 and older than 65, respectively. When stratified by decade cohorts, the complication rates were 9.04% for the <65 cohort, 13.46% for the 65 to 75 cohort, 16.17% for the >75 to 85 cohort, and 4.00% for the ≥85 cohort. Multivariable regression analysis revealed no statistically significant difference between the <65 and ≥65 age cohorts (odds ratio = 1.26; 95% confidence interval: 0.87-2.19). After stratifying into age cohorts, multivariable analyses revealed no difference in odds of postoperative complication occurrence for any age cohort when compared with the referent group (<65 years of age). CONCLUSION: Patients older than 65 years of age have significantly higher rates of complications after lumbar fusion when compared to younger patients. However, multivariable analysis revealed that age was not an independent risk factor for complication occurrence after lumbar fusion.

Routine, empathic and compassionate patient care: definitions, development, obstacles, education and beneficiaries.

RATIONALE: We believe that this study represents an innovative approach to clarifying the definitions of routine, empathic and compassionate health care, as well as of sympathy. We emphasize the importance of affective empathy and its intensification in the context of patient suffering (compassion), without abandoning the ideal of clinical equanimity. METHODS: We develop a pedagogical model for clinicians and trainees who are weaker in their empathic skills that includes four levels of growth. We clarify representative obstacles to empathic and compassionate care in education and clinical practice. We summarize the four beneficiaries of empathic and compassionate care (clinicians, patients, trainees, institutions). We suggest areas for future research, including the development of a compassion scale and conclude with a statement on how the conceptual and professional confusion we address adversely impacts patients and trainees. The article represents the consensus work of a group of health care professionals and students at Stony Brook University Hospital and School of Medicine who have been engaged in this project for several years through the Center for Medical Humanities, Compassionate Care, and Bioethics, established in August of 2008. CONCLUSIONS: We discern a shift away from concepts of clinical empathy and compassionate care that deny a significant place for an affective component and that idealize 'detachment'.

Biomechanical impact of C2 pedicle screw length in an atlantoaxial fusion construct.

BACKGROUND: Posterior, atlantoaxial (AA) fusions of the cervical spine may include either standard (26 mm) or short (16 mm) C2 pedicle screws. This manuscript focused on an in vitro biomechanical comparison of standard versus short C2 pedicle screws to perform posterior C1-C2 AA fusions. METHODS: Twelve human cadaveric spines underwent C1 lateral mass screw and standard C2 pedicle screw (n = 6) versus short C2 pedicle screw (n = 6) fixation. Six additional controls were not instrumented. The peak torque, peak rotational interval, and peak stiffness of the constructs were analyzed to failure levels. RESULTS: The peak torque to construct failure was not statistically significantly different among the control spine (12.2 Nm), short pedicle fixation (15.5 Nm), or the standard pedicle fixation (11.6 Nm), P = 0.79. While the angle at the peak rotation statistically significantly differed between the control specimens (47.7° of relative motion) and the overall instrumented specimens (P < 0.001), the 20.7° of relative rotation in the short C2 pedicle screw specimens was not statistically significantly higher than the 13.7° of relative rotation in the standard C2 pedicle screw specimens (P = 0.39). Similarly, although the average stiffness was statistically significantly lower in control group (0.026 Nm/degree) versus the overall instrumented specimens (P = 0.001), the standard C2 pedicle screws (2.54 Nm/degree) did not differ from the short C2 pedicle screws. CONCLUSIONS: Both standard and short C2 pedicle screws allow for equally rigid fixation of C1 lateral mass-C2 AA fusions. Usage of a short C2 pedicle screw may be an acceptable method of stabilization in carefully selected patient populations.

Concurrent neoadjuvant chemotherapy is an independent risk factor of stroke, all-cause morbidity, and mortality in patients undergoing brain tumor resection.

Neoadjuvant chemotherapy (NC) may be utilized for treatment of various tumors, and a proportion of patients on active NC may require resection of a primary or secondary brain tumor. The objective of this study is to examine the impact of NC on postoperative neurosurgical outcomes. Elective cranial neurosurgical patient data was obtained from the American College of Surgeons National Surgical Quality Improvement Program database between 2006 and 2012. The impact of NC on 30 day stroke, all-cause postoperative morbidity, and mortality were assessed. Adjusted odds ratios (OR) were estimated for stroke, overall morbidity, and mortality using a multivariable logistic regression model, accomplished in stepwise fashion, for patients receiving NC versus those not receiving NC. This study analyzed 3812 patients undergoing elective cranial surgery, with 152 on concurrent NC. NC patients had a complication rate of 23.68%, while patients not receiving NC had a lower complication rate at 17.65% (p=0.057). Multivariable regression analysis revealed that patients who received NC had significantly increased odds of developing a stroke with neurological deficit (OR 3.39; 95% confidence interval [CI] 1.37-8.40) and all-cause postoperative morbidity (OR 1.57; 95% CI 1.04-2.37) over the control group. Finally, the NC cohort demonstrated higher odds of mortality following surgery than their non-NC counterparts (OR 3.81; 95% CI 1.81-8.02). Ninety-two patients (2.41%) died within 30 days, of whom 10 (6.58%) were receiving NC versus 82 non-NC (2.24%) patients (p=0.001). Concurrent NC is associated with an increased risk of short-term stroke with neurological deficit, all-cause morbidity, and mortality in patients undergoing brain tumor resection.

Gold fiducials are a unique marker for localization in the thoracic spine: a cost comparison with percutaneous vertebroplasty.

We present a unique application of the gold fiducial as a preoperative, radiographic marker placed in the thoracic spine and used for intraoperative localization. In comparison to percutaneous vertebroplasty marking of thoracic spinal levels with polymethyl methacrylate (PMMA) cement, implantation of the gold fiducial is technically facile with a minimal learning curve. The fiducial markers are also associated with significantly less financial resources. Following 2013 Current Procedural Terminology (CPT) coding, the cost of vertebroplasty under fluoroscopic guidance, $3195·43, or under computed tomography (CT) guidance, $3232·54, is more than double the cost of the gold fiducial implantation - $1237·55 and $1267·03, under similar imaging techniques, respectively. In the first description of gold fiducials in the thoracic spine, we conclude that the marker is a safe and cost-effective method for preoperative localization of the thoracic levels.

Spontaneous regression of sequestrated lumbar disc herniations: Literature review.

Lumbar disc herniations (LDH) may regress with conservative management; however, this phenomenon is poorly understood for the sequestrated subtype of LDH. We present one of the first comprehensive literature reviews specifically addressing the spontaneous regression of sequestrated intervertebral discs. We reviewed all publications with lumbar disc herniations, sequestrated subtype. Our results were then narrowed to patients who experienced spontaneous regression of the sequestration. Based on our literature review of 53 cases, patients with sequestrated lumbar disc herniations experienced symptomatic resolution in a mean of 1.33±1.34 months and radiographic resolution in 9.27±13.32 months. Symptomatic patients with sequestrated discs present similarly to those with other types of lumbar disc herniations. Sequestrations may have the highest likelihood to radiographically regress in the shortest time frame in comparison to the remaining subtypes of LDH. The most likely mechanism for regression is an inflammatory response elicited against the free fragment. Patients with disc sequestrations may be managed conservatively, in the absence of intractable pain, inability to walk, weakness or symptoms suggestive of cauda equina syndrome.

Carbon dioxide induction of panic anxiety in schizophrenia with auditory hallucinations.

Panic is commonly co-morbid with schizophrenia. Panic may emerge prodromally, contribute to specific psychotic symptoms, and predict medication response. Panic is often missed due to agitation, impaired cognition, psychotic symptom overlap and limited clinician awareness. Carbon dioxide exposure has been used reliably to induce panic in non-psychotic panic subjects, but has not been systematically studied in schizophrenia. Eight inpatients with schizophrenia, recent auditory hallucinations, none preselected for panic, all on antipsychotic medication, received a structured Panic and Schizophrenia Interview (PaSI), assessing DSM-IV panic symptoms concurrent with paroxysmal auditory hallucinations. On that interview, all eight subjects reported panic concurrent with auditory hallucinations. At one sitting, subjects were exposed, in random order, to 35% carbon dioxide and to placebo room air, blinded to condition. All subjects experienced panic to carbon dioxide, one with limited symptoms. Only one subject panicked to placebo. One subject (one of only two without antipanic medication) had paroxysmal voices concurrent with induced panic. With added adjunctive clonazepam, that patient had marked clinical improvement and no response to carbon dioxide re-challenge. This first systematic examination offers preliminary evidence that carbon dioxide safely induces panic symptoms in schizophrenia. Panic may be prevalent and pathophysiologically significant in schizophrenia with auditory hallucinations.