Investigations into the route of uptake and pharmacokinetics of intraperitoneally-administered monoclonal antibodies: I. Transdiaphragmatic blockade of the terminal lymphatics in the rat

Recent studies on the intraperitoneal administration of radiolabeled monoclonal antibodies indicate that the diaphragm and, in particular, the lymphatics associated with the diaphragm are more involved in the transport of such high-molecular-mass moieties than was earlier suspected. The current study examines the role of the diaphragm in the i.p. transport of an IgG2a murine monoclonal antibody, 5G6.4, by observing the effect on the absorption of the antibody produced when the diaphragm has been scarred. Normal, sham-operated, and diaphragmatically scarred (abrasions made with 600-grade sandpaper) female Sprague Dawley rats (150–250 g) were administered intraperitoneal injections of 125 labeled 5G6.4 in a volume of 2.0 cm 3 . Approximately 5 µg antibody protein was administered in the individual 19-µCi injections per rat. Scarring was effective in partially blocking the amount of labeled antibody that crossed the diaphragm. Mean diaphragm levels (% injected dose/g) of 125 I-labeled 5G6.4 from the scarred group were 16.8% lower than values from the sham-operated rats and 37.2% lower than those from the control rats. The blockade was effective in slowing the appearance of the labeled antibody in the systemic circulation. The half-time to absorption was significantly prolonged in the scarred group; mean t 1/2 absorption values of 2.5 h for the control group, 5.3 h for the shamoperated group, and 9.6 h for the diaphragmatically blocked group were recorded. Scarring the diaphragm reduced the mean maximum blood concentration by 27.6% over the control group and 23.9% over the sham-operated group. The mean time to maximum blood concentration was lengthened by 93.0% over the control group and 35.3% over the sham-operated group due as a result of scarification. Presumably this impedence to absorption would increase the time that the radiolabeled antibody bathed the peritoneal space. The scarred group also had the largest “system mean residence time” (162.5 h) compared to the sham-operated (147.9 h) and control (118.7 h) groups. These values further verify the effect of surgery on the kinetics of the i.p. administered radiolabeled monoclonals. This work demonstrates that scarifying the diaphragm does alter the kinetics of the i.p. administered monoclonal antibodies and supports the concept that transdiaphragmatic lymphatic absorption is an important route of antibody clearance from the peritoneal cavity.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46857/1/262_2005_Article_BF01741408.pd

Flow-distributed spikes for Schnakenberg kinetics

This is the post-print version of the final published paper. The final publication is available at link.springer.com by following the link below. Copyright @ 2011 Springer-Verlag.We study a system of reaction–diffusion–convection equations which combine a reaction–diffusion system with Schnakenberg kinetics and the convective flow equations. It serves as a simple model for flow-distributed pattern formation. We show how the choice of boundary conditions and the size of the flow influence the positions of the emerging spiky patterns and give conditions when they are shifted to the right or to the left. Further, we analyze the shape and prove the stability of the spikes. This paper is the first providing a rigorous analysis of spiky patterns for reaction-diffusion systems coupled with convective flow. The importance of these results for biological applications, in particular the formation of left–right asymmetry in the mouse, is indicated.RGC of Hong Kon

Autoradiography-based, three-dimensional calculation of dose rate for murine, human-tumor xenografts

A Fast Fourier Transform method for calculating the three-dimensional dose rate distribution for murine, human-tumor xenografts is outlined. The required input includes evenly-spaced activity slices which span the tumor. Numerical values in these slices are determined by quantitative 125I autoradiography. For the absorbed dose-rate calculation, we assume the activity from both 131I- and 90Y-labeled radiopharmaceuticals would be distributed as is measured with the 125I label. Two example cases are presented: an ovarian-carcinoma xenograft with an IgG 2ak monoclonal antibody and a neuroblastoma xenograft with meta-iodobenzylguanidine (MIBG).Considering all the volume elements in a tumor, we show, by comparison of histograms and also relative standard deviations, that the measured 125I activity and the calculated 131I dose-rate distributions, are similarly non-uniform and that they are more non-uniform than the calculated 90Y dose-rate distribution. However, the maximum-to-minimum ratio, another measure of non-uniformity, decreases by roughly an order of magnitude from one distribution to the next in the order given above.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30498/1/0000126.pd

Relationship of physical activity and healthy eating with mortality and incident heart failure among community-dwelling older adults with normal body mass index

Aims Normal body mass index (BMI) is associated with lower mortality and may be achieved by physical activity (PA), healthy eating (HE), or both. We examined the association of PA and HE with mortality and incident heart failure (HF) among 2040 community-dwelling older adults aged ≥ 65 years with baseline BMI 18.5 to 24.99 kg/m2 during 13 years of follow-up in the Cardiovascular Health Study. Methods and results Baseline PA was defined as ≥500 weekly metabolic equivalent task-minutes and HE as ≥5 daily servings of vegetable and fruit intake. Participants were categorized into four groups: (i) PA−/HE− (n = 384); (ii) PA−/HE+ (n = 162); (iii) PA+/HE− (n = 992); and (iv) PA+/HE+ (n = 502). Participants had a mean age of 74 (±6) years, mean BMI of 22.6 (±1.5) kg/m2, 61% were women, and 4% African American. Compared with PA−/HE−, age-sex-race-adjusted hazard ratios and 95% confidence intervals for all-cause mortality for PA−/HE+, PA+/HE−, and PA+/HE+ groups were 0.96 (0.76–1.21), 0.61 (0.52–0.71), and 0.62 (0.52–0.75), respectively. These associations remained unchanged after multivariable adjustment and were similar for cardiovascular and non-cardiovascular mortalities. Respective demographic-adjusted hazard ratios (95% confidence intervals) for incident HF among 1954 participants without baseline HF were 1.21 (0.81–1.81), 0.71 (0.54–0.94), and 0.71 (0.51–0.98). These latter associations lost significance after multivariable adjustment. Conclusion Among community-dwelling older adults with normal BMI, physical activity, regardless of healthy eating, was associated with lower risk of mortality and incident HF, but healthy eating had no similar protective association in this cohort

Higher Risk for Incident Heart Failure and Cardiovascular Mortality among Community-Dwelling Octogenarians without Pneumococcal Vaccination

AIMS: Octogenarians have the highest incidence of heart failure (HF) that is not fully explained by traditional risk factors. We explored whether lack of pneumococcal vaccination is associated with higher risk of incident HF among octogenarians. METHODS AND RESULTS: In the Cardiovascular Health Study (CHS), 5290 community-dwelling adults, ≥65 years of age, were free of baseline HF and had data on pneumococcal vaccination. Of these, 851 were octogenarians, of whom, 593 did not receive pneumococcal vaccination. Multivariable-adjusted hazard ratios (aHR) and 95% confidence intervals (CI) for associations of lack of pneumococcal vaccination with incident HF and other outcomes during 13 years of follow-up were estimated using Cox regression models, adjusting for demographics and other HF risk factors including influenza vaccination. Octogenarians had a mean (±SD) age of 83 (±3) years; 52% were women and 17% African American. Overall, 258 participants developed HF and 662 died. Lack of pneumococcal vaccination was associated with higher relative risk of incident HF (aHR, 1.37; 95% CI, 1.01-1.85; P = 0.044). There was also higher risk for all-cause mortality (aHR, 1.23; 95% CI, 1.02-1.49; P = 0.028), which was mostly driven by cardiovascular mortality (aHR, 1.45; 95% CI, 1.06-1.98; P = 0.019). Octogenarians without pneumococcal vaccination had a trend toward higher risk of hospitalization due to pneumonia (aHR, 1.34; 95% CI, 0.99-1.81; P = 0.059). These associations were not observed among those 65-79 years of age. CONCLUSIONS: Among community-dwelling octogenarians, lack of pneumococcal vaccination was associated with a significantly higher independent risk of incident HF and mortality, and trend for higher pneumonia hospitalization

SN 2015as: A low luminosity Type IIb supernova without an early light curve peak

We present results of the photometric (from 3 to 509 days past explosion) and spectroscopic (up to 230 days past explosion) monitoring campaign of the He-rich Type IIb supernova (SN) 2015as. The {\it (B-V)} colour evolution of SN 2015as closely resemble those of SN 2008ax, suggesting that SN 2015as belongs to the SN IIb subgroup that does not show the early, short-duration photometric peak. The light curve of SN 2015as reaches the $B$-band maximum about 22 days after the explosion, at an absolute magnitude of -16.82 $\pm$ 0.18 mag. At $\sim$ 75 days after the explosion, its spectrum transitions from that of a SN II to a SN Ib. P~Cygni features due to He I lines appear at around 30 days after explosion, indicating that the progenitor of SN 2015as was partially stripped. For SN~2015as, we estimate a $^{56}$Ni mass of $\sim$ 0.08 M$_{\odot}$ and ejecta mass of 1.1--2.2 M$_{\odot}$, which are similar to the values inferred for SN 2008ax. The quasi bolometric analytical light curve modelling suggests that the progenitor of SN 2015as has a modest mass ($\sim$ 0.1 M$_{\odot}$), a nearly-compact ($\sim$ 0.05$\times$10$^{13}$ cm) H envelope on top of a dense, compact ($\sim$ 2$\times$10$^{11}$ cm) and a more massive ($\sim$ 1.2 M$_{\odot}$) He core. The analysis of the nebular phase spectra indicates that $\sim$ 0.44 M$_{\odot}$ of O is ejected in the explosion. The intensity ratio of the [Ca II]/[O I] nebular lines favours either a main sequence progenitor mass of $\sim$ 15 M$_{\odot}$ or a Wolf Rayet star of 20 M$_{\odot}$.Comment: 23 pages, 18 figures, 10 tables, Accepted for publication in MNRAS, 16 February, 201

Tbx6 Regulates Left/Right Patterning in Mouse Embryos through Effects on Nodal Cilia and Perinodal Signaling

Background: The determination of left/right body axis during early embryogenesis sets up a developmental cascade that coordinates the development of the viscera and is essential to the correct placement and alignment of organ systems and vasculature. Defective left-right patterning can lead to congenital cardiac malformations, vascular anomalies and other serious health problems. Here we describe a novel role for the T-box transcription factor gene Tbx6 in left/right body axis determination in the mouse. Results: Embryos lacking Tbx6 show randomized embryo turning and heart looping. Our results point to multiple mechanisms for this effect. First, Dll1, a direct target of Tbx6, is down regulated around the node in Tbx6 mutants and there is a subsequent decrease in nodal signaling, which is required for laterality determination. Secondly, in spite of a lack of expression of Tbx6 in the node, we document a profound effect of the Tbx6 mutation on the morphology and motility of nodal cilia. This results in the loss of asymmetric calcium signaling at the periphery of the node, suggesting that unidirectional nodal flow is disrupted. To carry out these studies, we devised a novel method for direct labeling and live imaging cilia in vivo using a genetically-encoded fluorescent protein fusion that labels tubulin, combined with laser point scanning confocal microscopy for direct visualization of cilia movement. Conclusions: We conclude that the transcription factor gene Tbx6 is essential for correct left/right axis determination in th

Live Cell Monitoring of hiPSC Generation and Differentiation Using Differential Expression of Endogenous microRNAs

Human induced pluripotent stem cells (hiPSCs) provide new possibilities for regenerative therapies. In order for this potential to be achieved, it is critical to efficiently monitor the differentiation of these hiPSCs into specific lineages. Here, we describe a lentiviral reporter vector sensitive to specific microRNAs (miRNA) to show that a single vector bearing multiple miRNA target sequences conjugated to different reporters can be used to monitor hiPSC formation and subsequent differentiation from human fetal fibroblasts (HFFs). The reporter vector encodes EGFP conjugated to the targets of human embryonic stem cell (hESC) specific miRNAs (miR-302a and miR-302d) and mCherry conjugated to the targets of differentiated cells specific miRNAs (miR-142-3p, miR-155, and miR-223). The vector was used to track reprogramming of HFF to iPSC. HFFs co-transduced with this reporter vector and vectors encoding 4 reprogramming factors (OCT4, SOX2, KLF4 and cMYC) were mostly positive for EGFP (67%) at an early stage of hiPSC formation. EGFP expression gradually disappeared and mCherry expression increased indicating less miRNAs specific to differentiated cells and expression of miRNAs specific to hESCs. Upon differentiation of the hiPSC into embryoid bodies, a large fraction of these hiPSCs regained EGFP expression and some of those cells became single positive for EGFP. Further differentiation into neural lineages showed distinct structures demarcated by either EGFP or mCherry expression. These findings demonstrate that a miRNA dependent reporter vector can be a useful tool to monitor living cells during reprogramming of hiPSC and subsequent differentiation to lineage specific cells

How to Achieve Fast Entrainment? The Timescale to Synchronization

Entrainment, where oscillators synchronize to an external signal, is ubiquitous in nature. The transient time leading to entrainment plays a major role in many biological processes. Our goal is to unveil the specific dynamics that leads to fast entrainment. By studying a generic model, we characterize the transient time to entrainment and show how it is governed by two basic properties of an oscillator: the radial relaxation time and the phase velocity distribution around the limit cycle. Those two basic properties are inherent in every oscillator. This concept can be applied to many biological systems to predict the average transient time to entrainment or to infer properties of the underlying oscillator from the observed transients. We found that both a sinusoidal oscillator with fast radial relaxation and a spike-like oscillator with slow radial relaxation give rise to fast entrainment. As an example, we discuss the jet-lag experiments in the mammalian circadian pacemaker