Distribution modeling quantifies collective TH cell decision circuits in chronic inflammation

Immune responses are tightly regulated by a diverse set of interacting immune cell populations. Alongside decision-making processes such as differentiation into specific effector cell types, immune cells initiate proliferation at the beginning of an inflammation, forming two layers of complexity. Here, we developed a general mathematical framework for the data-driven analysis of collective immune cell dynamics. We identified qualitative and quantitative properties of generic network motifs, and we specified differentiation dynamics by analysis of kinetic transcriptome data. Furthermore, we derived a specific, data-driven mathematical model for T helper 1 versus T follicular helper cell-fate decision dynamics in acute and chronic lymphocytic choriomeningitis virus infections in mice. The model recapitulates important dynamical properties without model fitting and solely by using measured response-time distributions. Model simulations predict different windows of opportunity for perturbation in acute and chronic infection scenarios, with potential implications for optimization of targeted immunotherapy.

Dissecting the dynamic transcriptional landscape of early T helper cell differentiation into Th1, Th2, and Th1/2 hybrid cells

Selective differentiation of CD4+ T helper (Th) cells into specialized subsets such as Th1 and Th2 cells is a key element of the adaptive immune system driving appropriate immune responses. Besides those canonical Th-cell lineages, hybrid phenotypes such as Th1/2 cells arise in vivo, and their generation could be reproduced in vitro. While master-regulator transcription factors like T-bet for Th1 and GATA-3 for Th2 cells drive and maintain differentiation into the canonical lineages, the transcriptional architecture of hybrid phenotypes is less well understood. In particular, it has remained unclear whether a hybrid phenotype implies a mixture of the effects of several canonical lineages for each gene, or rather a bimodal behavior across genes. Th-cell differentiation is a dynamic process in which the regulatory factors are modulated over time, but longitudinal studies of Th-cell differentiation are sparse. Here, we present a dynamic transcriptome analysis following Th-cell differentiation into Th1, Th2, and Th1/2 hybrid cells at 3-h time intervals in the first hours after stimulation. We identified an early bifurcation point in gene expression programs, and we found that only a minority of ~20% of Th cell-specific genes showed mixed effects from both Th1 and Th2 cells on Th1/2 hybrid cells. While most genes followed either Th1- or Th2-cell gene expression, another fraction of ~20% of genes followed a Th1 and Th2 cell-independent transcriptional program associated with the transcription factors STAT1 and STAT4. Overall, our results emphasize the key role of high-resolution longitudinal data for the characterization of cellular phenotypes.

Data-Driven Mathematical Model of Apoptosis Regulation in Memory Plasma Cells

Memory plasma cells constitutively produce copious amounts of antibodies, imposing a critical risk factor for autoimmune disease. We previously found that plasma cell survival requires secreted factors such as APRIL and direct contact to stromal cells, which act in concert to activate NF-κB- and PI3K-dependent signaling pathways to prevent cell death. However, the regulatory properties of the underlying biochemical network are confounded by the complexity of potential interaction and cross-regulation pathways. Here, based on flow-cytometric quantification of key signaling proteins in the presence or absence of the survival signals APRIL and contact to the stromal cell line ST2, we generated a quantitative model of plasma cell survival. Our model emphasizes the non-redundant nature of the two plasma cell survival signals APRIL and stromal cell contact, and highlights a requirement for differential regulation of individual caspases. The modeling approach allowed us to unify distinct data sets and derive a consistent picture of the intertwined signaling and apoptosis pathways regulating plasma cell survival.

Principles underlying the complex dynamics of temperature entrainment by a circadian clock

Autonomously oscillating circadian clocks resonate with daily environmental (zeitgeber) rhythms to organize physiology around the solar day. Although entrainment properties and mechanisms have been studied widely and in great detail for light-dark cycles, entrainment to daily temperature rhythms remains poorly understood despite that they are potent zeitgebers. Here we investigate the entrainment of the chronobiological model organism Neurospora crassa, subject to thermocycles of different periods and fractions of warm versus cold phases, mimicking seasonal variations. Depending on the properties of these thermocycles, regularly entrained rhythms, period-doubling (frequency demultiplication) but also irregular aperiodic behavior occurs. We demonstrate that the complex nonlinear phenomena of experimentally observed entrainment dynamics can be understood by molecular mathematical modeling.

Randomized phase II study of two gemcitabine schedules for patients with impaired performance status (Karnofsky performance status </= 70) and advanced non-small-cell lung cancer

PURPOSE

This randomized phase II study compared two treatment schedules of gemcitabine in patients with non-small-cell lung cancer (NSCLC) and impaired Karnofsky performance status (KP). Primary objectives were to record changes from baseline KP and to assess symptom palliation. Secondary objectives were overall survival, tumor response, and toxicity.

PATIENTS AND METHODS

Patients with stage IIIb and IV NSCLC and KP </= 70 were randomly assigned to receive gemcitabine 1,000 mg/m(2) on days 1, 8, and 15 of each 28-day cycle (3w4) or gemcitabine 1,500 mg/m(2) on days 1 and 8 of each 21-day cycle (2w3), both for up to six cycles. KP, toxicity, and SS14 lung cancer specific questions were recorded before each cycle of treatment. Response was evaluated 4 weeks after the last cycle.

RESULTS

One hundred seventy-four patients were enrolled. There was significant early attrition due to disease progression; only 61.5% of patients were alive at 2 months. There was a significant improvement in KP from baseline to pre-cycle 3 in both arms, with a trend in favor of the 3w4 regimen for duration and faster onset of improvement. Eight of the 17 quality-of-life (QOL) variables assessed showed an improvement of more than 10% between baseline and the start of the third cycle of treatment. Response rate, survival, and duration were similar in both arms.

CONCLUSION

There was no significant difference between the two schedules examined in terms of improvement in KP or QOL, but there seemed to be a trend in favor of the 3w4 schedule.

Clinical and quality of life outcomes in the first United Kingdom randomized trial of endobronchial brachytherapy (intraluminal radiotherapy) vs. external beam radiotherapy in the palliative treatment of inoperable non-small cell lung cancer

BACKGROUND AND PURPOSE

A randomized controlled trial was designed to evaluate the clinical and quality of life (QL) outcomes of patients receiving endobronchial brachytherapy (EBT) or external beam radiotherapy (XRT) as a primary palliative treatment in advanced lung cancer.

MATERIALS AND METHODS

Ninety-nine patients presenting de novo with lung cancer were randomized to receive EBT or XRT. Eleven key symptoms or clinical signs were assessed by clinicians and patient ratings using self-assessment questionnaires were obtained at the same time. The primary endpoints were a comparison of EBT and XRT for symptom relief and acute and late side-effects (palliation) and their effect on patients' functional status and patient-rated QL outcomes. A secondary objective was a comparison of clinician assessments with patient self-reported symptoms.

RESULTS

Both treatments produced good levels of symptom relief. They were better for XRT at the expense of more acute morbidity. Late side-effects were similar. The functional status of patients was well maintained and changed similarly with time in both groups. XRT gave a better duration of palliation. Twenty-eight percent of XRT patients required EBT (at a median time of 304 days) whereas 51% of EBT patients subsequently had XRT (at a median of 125 days). There was a significant modest gain in median survival with initial XRT (287 vs. 250 days). When clinician and patient assessments were compared, doctors were found to underestimate the severity of breathlessness, anorexia, tiredness and nausea.

CONCLUSIONS

Fractionated XRT is preferred to EBT as an initial treatment in better performance patients because it provides better overall and more sustained palliation with fewer retreatments and a modest gain in survival time. QL assessment is required in the evaluation of palliative treatments because clinicians frequently underestimate the incidence and severity of key symptoms.

Dose intensity in small cell lung cancer

Evidence from preclinical models and from clinical trials describing the importance of dose intensity in securing a better treatment outcome is reviewed. Recent randomized trials have shown statistically significant survival benefits with higher-dose, accelerated chemotherapy regimens with and without granulocyte colony-stimulating factor and granulocyte-macrophage colony-stimulating factor. The novel use of peripheral blood progenitor cells contained in whole blood autotransfusions, which allow a marked increase in dose intensity of an ifosfamide/carboplatin/etoposide regimen, could provide a much easier method of delivering dose-intensive chemotherapy than previously available.

Propofol and seizures

It is now clear that "seizure activity", excitatory phenomena, and/or a disorder of muscle tone are potential complications of the use of propofol. Whether this "seizure activity" is primarily, secondarily, or not at all a cerebral cortical event is still to be elucidated. Clearly propofol does have anticonvulsant activity, and also clearly it can produce an involuntary movement disorder, in certain patients, under certain conditions. Propofol is not the first anaesthetic drug to be implicated in the causation of seizures or abnormal movements nor indeed the first to appear to have anti-convulsant and proconvulsant activity (e.g. Althesin). While propofol has undoubtedly proved a very useful drug, the problem of convulsive phenomena creates a degree of background concern about its use. More needs to be known about the mechanism of this complication and any risk factors involved in determining who may have a seizure after propofol. In the clinical setting, the reporting of seizures possibly related to propofol should include--medical history, including personal or family history of epilepsy and movement disorders; a history of previous anaesthetics and whether propofol was used; regular medications; use of drugs or alcohol; history of chemical dependency; emotional state prior to induction; presence of hyperventilation or fever; a description of the alleged seizure, including rate of administration of propofol and amount given, time of onset of seizure in relation to time of drug administration, speed of onset of signs, quality of the abnormal movements, part of body involved, duration, any indication of a postictal state, any cardiovascular changes which may have accompanied the seizure, and any other possible triggers for the reaction such as other drugs used, including premedication; post seizure investigations including temperature, blood sugar, electrolytes, arterial gas analysis, neurological examination, EEG and CT scan. These actions and these investigations concerning propofol should not be delayed. It would appear appropriate to recommend to patients who experience apparent convulsive phenomena after propofol that they not be re-exposed to the drug.

Intensive combined-modality therapy in small cell lung cancer

Combination ifosfamide/carboplatin/etoposide (ICE) chemotherapy and ICE plus mid-cycle vincristine (VICE) are reviewed. Thoracic radiotherapy and prophylactic cranial irradiation given as single fractions in the majority of patients have been intercalated with VICE in the later studies. The patient populations have not been intensively staged with computed tomography, etc, but do have reasonable Karnofsky performance status ratings and biochemical screens. A policy of no dose reduction over six courses of VICE chemotherapy has been followed in three consecutive studies of 166 patients. The minimum length of follow-up is 26 months and the 2-year survival rate is > or = 30%. Hematopoietic growth factor support in an attempt to overcome the considerable myelosuppression with VICE therapy is currently being evaluated.

Therapy for small cell lung cancer using carboplatin, ifosfamide, etoposide (without dose reduction), mid-cycle vincristine with thoracic and cranial irradiation

The aim of this study was to assess the efficacy and toxicity of intensive chemotherapy, administered without dose reduction, with cranial and thoracic radiotherapy given when possible as a single fraction in small cell lung cancer. 87 patients were eligible on the basis of good performance status, normal or near normal biochemistry and clinical staging, 73 limited and 14 extensive stage, computed tomography scanning was not mandatory. Six cycles of carboplatin, ifosfamide and etoposide with vincristine on day 15 at 4 weekly intervals were planned. Dosages were not reduced in response to myelosuppression. Prophylactic cranial irradiation (PCI) as a single fraction after the first cycle and thoracic irradiation (when possible as a single fraction) following the third cycle were delivered. Seventy-two per cent of patients completed the protocol. Complete response rate was 55% and 26% of patients had a partial response. The median nadirs of neutropenia were 0.5 x 10(9)/l and thrombocytopenia 14 x 10(9)/l, with 6% probable treatment-related deaths. Performance status and dyspnoea improved markedly to normal or near normal levels following the second course. Brain metastases occurred in 13% of patients. The median survival was 16.2 months with a 2-year survival of 31% (95% confidence interval, 24-41%) for a minimum follow-up of 26 months. These results compare favourably with other combined modality studies, using multiple radiotherapy fractions with cisplatin-based combinations and dosage reduction for patients staged in more anatomical detail. The toxicity spectrum and efficacy data could lead to the use of this chemotherapy regimen with haematopoietic growth factors and, in the future, peripheral blood progenitor cell rescue.

Neurological and cognitive impairment in long-term survivors of small cell lung cancer

Despite its effectiveness in reducing the rate of brain metastases, the role of prophylactic cranial irradiation (PCI) in the management of small cell lung cancer (SCLC) remains controversial because of concern about radiation-induced neurological morbidity. In order to evaluate morbidity and its impact on quality of life 64 patients surviving > or = 2 years in remission were recalled for assessment. 52 had received PCI. Most of the patients were well: 95% had performance status < or = 1 and nine out of 37 neurological examinations were abnormal. On neuropsychometric testing, only 19% of patients performed at the level expected for their age and intellectual ability on all four tests used. Fifty-four per cent of patients were impaired on two or more of the tests, suggesting a significant degree of measurable cognitive dysfunction. The number of patients who had not received PCI was insufficient for comparative analysis with the number who had, but among those treated with PCI, patients receiving 8 Gy in 1 fraction appeared less impaired than those receiving higher radiation doses in multiple fractions. The study showed that neuropsychometric testing is acceptable to patients, can be administered by non-psychologists in the clinic and is sensitive to otherwise undetected deficits of cognitive function in this patient population. Prospective evaluation of PCI should include neuropsychometric testing.

Intensive therapy for small-cell lung cancer using carboplatin alternating with cisplatin, ifosfamide, etoposide, mid-cycle vincristine, and radiotherapy

Forty patients with small-cell lung cancer (31 patients with limited-stage [LS] disease, and nine patients with extensive-stage [ES] disease but of good performance status) have been treated with an intensive therapy composed of carboplatin alternating with cisplatin, ifosfamide, and etoposide with vincristine on day 14 of each carboplatin cycle. A maximum of six cycles were administered at 3 weekly intervals after the cisplatin combination and 4 weekly after the carboplatin combination. Prophylactic cranial irradiation was given with the first cycle of chemotherapy and thoracic irradiation with the third cycle. The median nadir for neutrophils was 0.47 x 10(9)/L and for platelets, 40 x 10(9)/L. Chemotherapy dosages were not reduced in response to myelosuppression, but treatment was delayed to allow blood count recovery. Sixty-eight percent of patients received all six cycles of chemotherapy, and there were four deaths associated with treatment-related neutropenia. Twenty-eight patients (70%) achieved a complete response (CR) when assessed 1 month after the end of treatment, and a further five patients (12.5%) had a partial response (PR). Median duration of CR was 16 months and of PR, 8 months. Cerebral metastases occurred in 20% of all patients and was the apparent sole site of relapse in 11% of the CR patients. The median survival of the total group was 14 months with an actual 2-year survival of 30% and a minimum follow-up of 28 months.

Weight loss and change in resting metabolic rate

The relation between change in resting metabolic rate (RMR) and change in fat-free mass (FFM) after weight loss is not well understood and is often inappropriately expressed in kilocalories per unit of FFM. We measured RMR and FFM in 35 obese patients enrolled in a conservative weight-loss program. RMR per kilogram FFM was not different after weight loss. However, the regression of delta RMR on delta FFM revealed that the decline in RMR tended to be greater than could be accounted for by loss of FFM. At initial test and retest, body fat (Fat) was not a predictor of RMR after FFM had been taken into account but delta Fat significantly contributed to the prediction of delta RMR when added to the equation after delta FFM. Thus, people losing larger amounts of weight had declines in RMR greater than could be accounted for by loss of FFM. Self-reported age of onset of obesity was not related to delta RMR.

Modifications of the classical notion of Panum's fusional area

It is generally believed that there is an absolute disparity limit for binocular fusion; objects with disparities within this limit, known as Panum's fusional area, will appear fused and single, while objects with disparities outside the limit appear double. It is demonstrated, however, that the disparity gradient, rather than the disparity magnitude, dictates binocular fusion when several objects occur near one another in the visual field. The disparity gradient is defined as the difference between the disparities of neighboring objects divided by their angular separation. If this ratio exceeds a critical value (approximately 1) then fusion does not occur, even though the absolute disparities of the individual objects may be well within the classical Panum's area. This discovery leads to the reinterpretation of several enigmatic phenomena in stereopsis, including Panum's limiting case.

A disparity gradient limit for binocular fusion

Ever since Panum, it has been commonly assumed that there is an absolute disparity limit for binocular fusion. It is now found that nearby objects modify this disparity limit. This result sheds new light on several enigmatic phenomena in stereopsis.