Extracellular-to-Intracellular Fluid Volume Ratio as a Prognostic Factor for Survival in Patients With Metastatic Cancer

Purpose: This study aimed to investigate whether the extracellular-to-intracellular fluid volume (E/I) ratio can predict survival in patients with metastatic cancer. Methods: Clinical data were collected from April 2016 to March 2018. Patients aged ≥19 years with metastatic solid tumor were eligible. Bioimpedance analysis was used to assess body fluid distribution and the E/I ratio. Clinical characteristics, including laboratory test results and nutrition status according to the E/I ratio, were analyzed. Cox proportional hazards models and Kaplan-Meier analysis were used to identify risk factors for mortality. Results: In total, 87 patients were included in the study. The 87 patients were divided into 2 groups according to the median E/I ratio: a high E/I group (E/I ratio ≥1.0, n = 43) and a low E/I group (E/I ratio <1.0, n = 44). Poor performance status, fluid retention, malnutrition, elevation of C-reactive protein levels, and decreases in hemoglobin, albumin, and protein levels were significantly associated with the high E/I group. The median overall survival time was 1.6 and 12.5 months in the high E/I and low E/I groups, respectively (P < .001). In the multivariate analysis, poor performance status, leukocytosis, fluid retention, and E/I ratio were independent prognostic factors, and the E/I ratio was the strongest prognostic factor predicting overall survival (hazard ratio = 3.49, 95% confidence interval = 1.75-6.96, P < .001). Conclusions: The E/I ratio can predict survival time in patients with metastatic cancer. More rigorous research is required to confirm this result.

Comparison of the Body Composition of Caucasian Young Normal Body Mass Women, Measured in the Follicular Phase, Depending on the Carbohydrate Diet Level

Background and objectives: Some publications indicate the possibility of the influence of meal nutritional value on results of bioelectrical impedance, and of the relation between the long-term carbohydrate intake and body composition. The aim of the presented study was to evaluate the influence of long-term intake of carbohydrates on body composition results assessed using the bioelectrical impedance of Caucasian young women with normal body mass, who were in the follicular phase of their menstrual cycle. Materials and Methods: Body composition was assessed in 100 women (18–30 years), according to strict rules, to minimize the influence of disturbing factors and by using two types of bioelectrical impedance device of the same operator to eliminate the influence of measurement (BIA 101/SC and BIA 101/ASE by Akern Srl, Firenze, Italy with the Bodygram 1.31 software and its equations by Akern Srl, Firenze, Italy). The analysis included validation of reproducibility of body composition assessment (fat, fat-free, body cell and muscle mass, water, extracellular water, and intracellular water content), and comparison of body composition for groups characterized by carbohydrate content <50% (n = 55) and >50% of the energy value of the diet (n = 45). Results: Analysis conducted using Bland–Altman method, analysis of correlation, analysis of quartile distribution, and weighted κ statistic revealed a positively validated reproducibility, but extracellular water associations were the weakest. Depending on the device, participants characterized by higher carbohydrate intake had significantly higher intracellular water content (p = 0.0448), or close to significantly higher (p = 0.0851) than those characterized by lower carbohydrate intake, whose extracellular water content was close to significantly lower (p = 0.0638) or did not differ. Conclusions: The long-term, moderately reduced, carbohydrate intake may cause the shift of intracellular water to the extracellular space and, as a result, influence the body composition results.

Does lymphadenectomy have influence on postoperative body fluid distribution?

OBJECTIVE

We compared the fluid volume parameters in women undergoing gynaecological surgery for benign and malignant conditions before and after surgery using bioelectrical impedance vectors.

STUDY DESIGN

A total of 181 patients were enrolled. In all, 89 patients had surgery for benign conditions and 92 patients underwent oncological procedures, including lymph node dissection, for malignant diseases. Bioelectrical impedance analysis (BIA) parameters were measured on the day of hospitalisation before any treatment and at 24h and 1 month after the surgical intervention. The BIA parameters measured included extracellular water (ECW), intracellular water (ICW), and total body water (TBW).

RESULTS

TBW increased significantly 1 month after surgery in all cases (p<0,05 in both group). ECW was significantly higher (p<0.05) and ICW was significantly lower (p<0,05) in the malignant group than the benign group.

CONCLUSION

Radical gynaecological surgeries, including lymph node dissection, have a greater effect on body water distribution than surgeries performed for benign conditions.

Bioimpedance Spectroscopy for Clinical Assessment of Fluid Distribution and Body Cell Mass

Body composition assessment has been used to evaluate clinical interventions in research trials, and has the potential to improve patient care in the clinical setting. Body cell mass (BCM) is an important indicator of nutrition status; however, its measurement in the clinic has been limited. BCM can be estimated by the measurement of intracellular water (ICW). The assessment of extracellular water (ECW) is also important because many clinical populations undergo alterations in fluid distribution, particularly individuals with wasting, those receiving dialysis, and obese individuals. Bioimpedance spectroscopy (BIS) is a unique bioimpedance approach that differs in underlying basis from the more readily recognized single-frequency bioelectrical impedance analysis (SF-BIA) in that it does not require the use of statistically derived, population-specific prediction equations. It has the potential advantage of not only measuring total body water (TBW), as does SF-BIA, but also offering the unique capacity to differentiate between ECW and ICW and, thus, to provide an estimate of BCM. This literature review was conducted to compare available BIS devices to multiple dilution for measuring fluid compartments or BCM in a number of populations. Variable results regarding the ability of BIS to measure absolute volumes, as well as the observation of wide limits of variation, make BIS problematic for individual assessment in the clinic, particularly in populations with abnormal fluid distribution or body geometry. BIS has been found to be more accurate for measuring changes in fluid volumes or BCM, particularly in post-surgical and human immunodeficiency virus (HIV)-infected individuals. It is certainly possible that population-specific adjustments may improve the accuracy of BIS for assessing individuals in the clinical setting; however, additional research and development is needed before the method can be accepted for routine clinical use.

Intracellular freezing in the infective juveniles of Steinernema feltiae: an entomopathogenic nematode

Taking advantage of their optical transparency, we clearly observed the third stage infective juveniles (IJs) of Steinernema feltiae freezing under a cryo-stage microscope. The IJs froze when the water surrounding them froze at -2°C and below. However, they avoid inoculative freezing at -1°C, suggesting cryoprotective dehydration. Freezing was evident as a sudden darkening and cessation of IJs' movement. Freeze substitution and transmission electron microscopy confirmed that the IJs of S. feltiae freeze intracellularly. Ice crystals were found in every compartment of the body. IJs frozen at high sub-zero temperatures (-1 and -3°C) survived and had small ice crystals. Those frozen at -10°C had large ice crystals and did not survive. However, the pattern of ice formation was not well-controlled and individual nematodes frozen at -3°C had both small and large ice crystals. IJs frozen by plunging directly into liquid nitrogen had small ice crystals, but did not survive. This study thus presents the evidence that S. feltiae is only the second freeze tolerant animal, after the Antarctic nematode Panagrolaimus davidi, shown to withstand extensive intracellular freezing.

Roles of cell walls and intracellular contents in supercooling capability of xylem parenchyma cells of boreal trees

The supercooling capability of xylem parenchyma cells (XPCs) in boreal hardwood species differs depending not only on species, but also season. In this study, the roles of cell walls and intracellular contents in supercooling capability of XPCs were examined in three boreal hardwood species, Japanese beech, katsura tree and mulberry, whose supercooling capability differs largely depending on species and season. XPCs in these species harvested in winter and summer were treated by rapid freezing and thawing (RFT samples) or by RFT with further washing (RFTW samples) to remove intracellular contents from XPCs in order to examine the roles of cell walls in supercooling. RFT samples were also treated with glucose solution (RFTG samples) to examine roles of intracellular contents in supercooling. The supercooling capabilities of these samples were examined by differential thermal analysis after ultrastructural observation of XPCs by a cryo-scanning electron microscope to confirm effects of the above treatments. XPCs in RFTW samples showed a large reduction in supercooling capability to similar temperatures regardless of species or season. On the other hand, XPCs in RFTG samples showed a large increase in supercooling capability to similar temperatures regardless of species or season. These results indicate that although cell walls have an important role in maintenance of supercooling, change in supercooling capability of XPCs is induced by change in intracellular contents, but not by change in cell wall properties.

Haemodiafiltration results in similar changes in intracellular water and extracellular water compared to cooled haemodialysis

BACKGROUND/AIMS

Intradialytic hypotension is the most common complication of modern day haemodialysis (HD). Convective modalities, including haemodiafiltration (HDF) are reported to result in greater cardiovascular stability compared to standard HD, which has been suggested to be due to improved solute transport between compartments. We therefore investigated the effect of treatment on body water by bioimpedance.

METHODS

We measured the change in extracellular water (ECW) and intracellular water (ICW) in 263 outpatients attending for HD using cooled dialysate and 134 patients for HDF.

RESULTS

Patient cohorts were matched for demographics, dialysate composition, ultrafiltration rate, and session duration. The fall in systolic blood pressure following HD was -11.8 mm Hg (-25.3 to 2.3) and not different from that following HDF -12 mm Hg (-27 to 6). Similarly there were no differences in pretreatment serum sodium and dialysate sodium gradient [HD 1 mmol/l (-1 to 3) vs. HDF 2 mmol/l (1 to 4)], or change in serum sodium posttreatment [HD 0 mmol/l (-2 to 2) vs. HDF 1 mmol/l (-1 to 3)]. There were no differences in ICW or ECW pretreatment, and following treatment the reduction in ICW and ECW did not differ [ICW HD -3.5% (-5.7 to -1.8) vs. -4.1% (-6.0 to -1.7), ECW HD -7.1% (-9.4 to -4.7) vs. HDF -7.1% (-9.7 to -4.9)].

CONCLUSION

We were unable to demonstrate any advantage for HDF over HD using cooled dialysate in terms of changes in blood pressure during a treatment session, or differences in the relative changes in ICW or ECW volumes.

Molecular determinants of A2AR-D2R allosterism: role of the intracellular loop 3 of the D2R

In the CNS, an antagonistic interaction has been shown between adenosine A(2A) and dopamine D(2) receptors (A(2A)Rs and D(2)Rs) that may be relevant both in normal and pathological conditions (i.e., Parkinson's disease). Thus, the molecular determinants mediating this receptor-receptor interaction have recently been explored, as the fine tuning of this target (namely the A(2A)R/D(2)R oligomer) could possibly improve the treatment of certain CNS diseases. Here, we used a fluorescence resonance energy transfer-based approach to examine the allosteric modulation of the D(2)R within the A(2A)R/D(2)R oligomer and the dependence of this receptor-receptor interaction on two regions rich in positive charges on intracellular loop 3 of the D(2)R. Interestingly, we observed a negative allosteric effect of the D(2)R agonist quinpirole on A(2A)R ligand binding and activation. However, these allosteric effects were abolished upon mutation of specific arginine residues (217-222 and 267-269) on intracellular loop 3 of the D(2)R, thus demonstrating a major role of these positively charged residues in mediating the observed receptor-receptor interaction. Overall, these results provide structural insights to better understand the functioning of the A(2A)R/D(2)R oligomer in living cells.

Intracellular-signaling tumor-regression modeling of the pro-apoptotic receptor agonists dulanermin and conatumumab

Dulanermin (rhApo2L/TRAIL) and conatumumab bind to transmembrane death receptors and trigger the extrinsic cellular apoptotic pathway through a caspase-signaling cascade resulting in cell death. Tumor size time series data from rodent tumor xenograft (COLO205) studies following administration of either of these two pro-apoptotic receptor agonists (PARAs) were combined to develop a intracellular-signaling tumor-regression model that includes two levels of signaling: upstream signals unique to each compound (representing initiator caspases), and a common downstream apoptosis signal (representing executioner caspases) shared by the two agents. Pharmacokinetic (PK) models for each drug were developed based on plasma concentration data following intravenous and/or intraperitoneal administration of the compounds and were used in the subsequent intracellular-signaling tumor-regression modeling. A model relating the PK of the two PARAs to their respective and common downstream signals, and to the resulting tumor burden was developed using mouse xenograft tumor size measurements from 448 experiments that included a wide range of dose sizes and dosing schedules. Incorporation of a pro-survival signal--consistent with the hypothesis that PARAs may also result in the upregulation of pro-survival factors that can lead to a reduction in effectiveness of PARAs with treatment--resulted in improved predictions of tumor volume data, especially for data from the long-term dosing experiments.

Strength-duration relationship for intra- versus extracellular stimulation with microelectrodes

Chronaxie, a historically introduced excitability time parameter for electrical stimulation, has been assumed to be closely related to the time constant of the cell membrane. Therefore, it is perplexing that significantly larger chronaxies have been found for intracellular than for extracellular stimulation. Using compartmental model analysis, this controversy is explained on the basis that extracellular stimulation also generates hyperpolarized regions of the cell membrane hindering a steady excitation as seen in the intracellular case. The largest inside/outside chronaxie ratio for microelectrode stimulation is found in close vicinity of the cell. In the case of monophasic cathodic stimulation, the length of the primarily excited zone which is situated between the hyperpolarized regions increases with electrode-cell distance. For distant electrodes this results in an excitation process comparable to the temporal behavior of intracellular stimulation. Chronaxie also varies along the neural axis, being small for electrode positions at the nodes of Ranvier and axon initial segment and larger at the soma and dendrites. As spike initiation site can change for short and long pulses, in some cases strength-duration curves have a bimodal shape, and thus, they deviate from a classical monotonic curve as described by the formulas of Lapicque or Weiss.

[Use of integral two-frequency impedanciometry in clinical monitoring in patients with acute destructive pancreatitis]

The paper gives the results of studying the body water compartments and impedance parameters in 69 patients with acute destructive pancreatitis during postoperative period, by means of non-invasive integral two-frequency impedancometry. Progressing extracellular hyperhydratation and decreased total electrical impedance of body tissue accompanied by increased number of general and intraabdominal complications, mortality, that determine the prognostic significance of these criteria.

Hypothermia and rewarming injury in hippocampal neurons involve intracellular Ca2+ and glutamate excitotoxicity

This study examines the causes of hypothermia and rewarming injury in CA1, CA3, and dentate neurons in rat hippocampal slice cultures. Neuronal death, assessed with propidium iodide or Sytox fluorescence, Fluoro-Jade labeling, and Cresyl Violet staining, depended on the severity and duration of hypothermia. More than 6 h at temperatures less than 12 °C followed by rewarming to 37 °C (profound hypothermia and rewarming, PH/RW) caused swelling and death in large number of neurons in CA1, CA3, and dentate. During PH, [ATP] decreased and [Ca(2+)](I) and extracellular [glutamate] increased, with neuron rupture and nuclear condensation following RW. The data support the hypothesis that neuronal death from PH/RW is excitotoxic, due to ATP loss, glutamate receptor activation and Ca(2+) influx. We found that antagonism of N-methyl-D-aspartate (NMDA) receptors, but not 2-amino-3-(5-methyl-3-oxo-1,2- oxazol-4-yl) propanoic acid or metabotropic glutamate receptors, decreased neuron death and prevented increases in [Ca(2+)](I) caused by PH/RW. Chelating extracellular Ca(2+) decreased PH/RW injury, but inhibiting L- and T-type voltage-gated Ca(2+) channels, K+ channels, Ca(2+) release from the endoplasmic reticulum, and reverse Na(+)/Ca(2+) exchange did not affect the Ca(2+) changes or cell death. We conclude that the mechanism of PH/RW neuronal injury in hippocampal slices primarily involves intracellular Ca(2+) accumulation mediated by NMDA receptors that activates necrotic, but not apoptotic processes.

[Cell as an integral water-dependent system in onthogenesis]

The study proposes a model of plant cell as an integral physical and physical-chemical water-dependent system of maximum structural complexity and complete combination of functions. The framework of this model allows analyzing any cell of simpler organization in any degree of reduction, animal cell included. The model justifies priority in the establishment of internal and functional (turgor) cell pressure of its cytoplasmatic solution high-molecular component along the chain: genome-->protein (quality and quantity)-->functional(turgor) pressure-->cell internal pressure-->water content in cell, gradual decrease of which results in cell death.

POSH is an intracellular signal transducer for the axon outgrowth inhibitor Nogo66

Myelin-derived inhibitors limit axon outgrowth and plasticity during development and in the adult mammalian CNS. Nogo66, a functional domain of the myelin-derived inhibitor NogoA, signals through the PirB receptor to inhibit axon outgrowth. The signaling pathway mobilized by Nogo66 engagement of PirB is not well understood. We identify a critical role for the scaffold protein Plenty of SH3s (POSH) in relaying process outgrowth inhibition downstream of Nogo66 and PirB. Blocking the function of POSH, or two POSH-associated proteins, leucine zipper kinase (LZK) and Shroom3, with RNAi in cortical neurons leads to release from myelin and Nogo66 inhibition. We also observed autocrine inhibition of process outgrowth by NogoA, and suppression analysis with the POSH-associated kinase LZK demonstrated that LZK operates downstream of NogoA and PirB in a POSH-dependent manner. In addition, cerebellar granule neurons with an RNAi-mediated knockdown in POSH function were refractory to the inhibitory action of Nogo66, indicating that a POSH-dependent mechanism operates to inhibit axon outgrowth in different types of CNS neurons. These studies delineate an intracellular signaling pathway for process outgrowth inhibition by Nogo66, comprised of NogoA, PirB, POSH, LZK, and Shroom3, and implicate the POSH complex as a potential therapeutic target to enhance axon outgrowth and plasticity in the injured CNS.

Changes and role of adrenoceptors in PC12 cells after phenylephrine administration and apoptosis induction

The present study addresses the hypothesis that adrenergic regulation modulates the effect of apoptosis. Therefore we studied, whether α1-adrenergic receptor's agonist phenylephrine (PE) can affect or induce apoptosis in rat pheochromocytoma (PC12) cells. We have shown that PE treatment did not increase level of the apoptosis, or level of the caspase 3 mRNA. When apoptosis was induced in the presence of PE, caspase 3 mRNA was significantly increased, while the percentage of apoptotic cells remained unchanged compared to apoptotic group without PE. During this process, α1D-, β2- and β3-adrenergic receptors (ARs) were upregulated. Since all these three types of ARs are differently localized in the cell, we assume that mutual communication of all three ARs is crucial to participate in this signaling and during development of apoptosis, some of these systems might translocate. Another important system in handling noradrenaline during apoptosis might be noradrenaline transporter (NET), since it was downregulated in apoptotic cells treated with PE, compared to untreated apoptotic cells. However, precise mechanism of mutual communication among all these systems remains to be elucidated.

Information-optimal transcriptional response to oscillatory driving

Intracellular transmission of information via chemical and transcriptional networks is thwarted by a physical limitation: The finite copy number of the constituent chemical species introduces unavoidable intrinsic noise. Here we solve for the complete probabilistic description of the intrinsically noisy response to an oscillatory driving signal. We derive and numerically verify a number of simple scaling laws. Unlike in the case of measuring a static quantity, response to an oscillatory signal can exhibit a resonant frequency which maximizes information transmission. Furthermore, we show that the optimal regulatory design is dependent on biophysical constraints (i.e., the allowed copy number and response time). The resulting phase diagram illustrates under what conditions threshold regulation outperforms linear regulation.

A numerical model of cellular blebbing: a volume-conserving, fluid-structure interaction model of the entire cell

In animal cells, blebs are smooth, quasi-hemispherical protrusions of the plasma membrane that form when a section of the membrane detaches from the underlying actin cytoskeleton and is inflated by flowing cytosol. The mechanics behind this common cellular activity are not yet clear. As a first step in the development of a full computational framework, we present a numerical model of overall cell behavior based upon the interaction between a background Newtonian-fluid cytosol and elastic structures modeling the membrane and filaments. The detailed micromechanics of the cytoskeletal network are the subject of future work. Here, the myosin-driven contraction of the actin network is modeled through stressed elastic filaments. Quantitative models of cytoskeletal micromechanics and biochemistry require accurate estimates of local stress and flow conditions. The main contribution of this paper is the development of a computationally efficient fluid-structure interaction model based on operator splitting, to furnish this data. Cytosol volume conservation (as supported by experimental evidence) is enforced through an intermediate energy minimization step. Realistic bleb formation and retraction is observed from this model, offering an alternative formulation to positing complex continuum behavior of the cytoplasm (e.g. poroelastic model of Charras et al., 2008).

Cell-autonomous intracellular androgen receptor signaling drives the growth of human prostate cancer initiating cells

BACKGROUND

The lethality of prostate cancer is due to the continuous growth of cancer initiating cells (CICs) which are often stimulated by androgen receptor (AR) signaling. However, the underlying molecular mechanism(s) for such AR-mediated growth stimulation are not fully understood. Such mechanisms may involve cancer cell-dependent induction of tumor stromal cells to produce paracrine growth factors or could involve cancer cell autonomous autocrine and/or intracellular AR signaling pathways.

METHODS

We utilized clinical samples, animal models and a series of AR-positive human prostate cancer cell lines to evaluate AR-mediated growth stimulation of prostate CICs.

RESULTS

The present studies document that stromal AR expression is not required for prostate cancer growth, since tumor stroma surrounding AR-positive human prostate cancer metastases (N = 127) are characteristically AR-negative. This lack of a requirement for AR expression in tumor stromal cells is also documented by the fact that human AR-positive prostate cancer cells grow equally well when xenografted in wild-type versus AR-null nude mice. AR-dependent growth stimulation was documented to involve secretion, extracellular binding, and signaling by autocrine growth factors. Orthotopic xenograft animal studies documented that the cellautonomous autocrine growth factors which stimulate prostate CIC growth are not the andromedins secreted by normal prostate stromal cells. Such cell autonomous and extracellular autocrine signaling is necessary but not sufficient for the optimal growth of prostate CICs based upon the response to anti-androgen plus/or minus preconditioned media.

CONCLUSIONS

AR-induced growth stimulation of human prostate CICs requires AR-dependent intracellular pathways. The identification of such AR-dependent intracellular pathways offers new leads for the development of effective therapies for prostate cancer.

Secretogranin III is an astrocyte granin that is overexpressed in reactive glia

Astrocytes release peptide and nonpeptide transmitters that influence neuronal development, function, and plasticity. However, the molecular components of the astroglial secretory pathways in vivo are largely unknown. Here, we analyze in astrocytes the production, expression regulation, trafficking, and release of secretogranin III (SgIII), a member of the multifunctional granin family. We show that astroglial cells in culture synthesize and release a nonprocessed form of SgIII. In vivo studies show that many neuronal populations produce and transport SgIII. In particular, the highest SgIII expression in the cerebral cortex in vivo is present in astroglial cells. Both SgIII protein and mRNA are abundantly detected in cortical astrocytes and in Bergmann glial cells. Moreover, the levels of SgIII mRNA and protein in reactive astrocytes, induced by perforating injury increase dramatically. These results implicate SgIII in the astrocyte secretory pathway in vivo and show that its expression is finely regulated during glial activation. The robust expression of SgIII in astrocytes and its regulation in the injured brain suggest both intracellular and extracellular roles for this glial granin in the physiology and repair/damage of neuronal circuits.

Intensive RNAi with lentiviral vectors in mammalian cells

RNAi is a powerful technology for analyzing gene function in human cells. However, its utility can be compromised by inadequate knockdown of the target mRNA or by interpretation of effects without rigorous controls. We review lentiviral vector-based methods that enable transient or stable knockdowns to trace mRNA levels in human CD4+ T cell lines and other targets. Critical controls are reviewed, including rescue of the pre-knockdown phenotype by re-expression of the targeted gene. The time from thinking about a potential knockdown target to analysis of phenotypes can be as short as a few weeks.

The techniques and uses of intracellular pH measurements

Weak-acid, 31P-nuclear magnetic resonance (NMR) and microelectrode techniques for measuring intracellular pH (pHi) are compared by demonstration of their use in rat liver. The ultimate test of suitability of these methods is the confidence with which they can be used to clarify aspects of metabolic regulation, translocation of substances across biological membranes, and the control of cell pH itself. Though resting pHi in perfused liver is fairly similar with all three techniques, substantial quantitative differences between values obtained with 31P NMR and microelectrodes are revealed after addition of fructose to the perfused liver preparation. The use and limitations of weak-acid methods in determining the mechanism of inhibition of gluconeogenesis from lactate by acidosis and in determining the pH responsiveness of the lactate transporter in the hepatocyte plasma membrane are demonstrated. Microelectrode-derived values of pHi are probably referable to the bulk phase of the cytosol, whereas values from the other two methods are more complex in their interpretation. Microelectrode and NMR methods have the great advantage of being non-destructive, and continuous records may be obtained.

Intracellular microrheology of motile Amoeba proteus

The motility of Amoeba proteus was examined using the technique of passive particle tracking microrheology, with the aid of newly developed particle tracking software, a fast digital camera, and an optical microscope. We tracked large numbers of endogeneous particles in the amoebae, which displayed subdiffusive motion at short timescales, corresponding to thermal motion in a viscoelastic medium, and superdiffusive motion at long timescales due to the convection of the cytoplasm. Subdiffusive motion was characterized by a rheological scaling exponent of 3/4 in the cortex, indicative of the semiflexible dynamics of the actin fibers. We observed shear-thinning in the flowing endoplasm, where exponents increased with increasing flow rate; i.e., the endoplasm became more fluid-like. The rheology of the cortex is found to be isotropic, reflecting an isotropic actin gel. A clear difference was seen between cortical and endoplasmic layers in terms of both viscoelasticity and flow velocity, where the profile of the latter is close to a Poiseuille flow for a Newtonian fluid.

Enrollment fluid status is independently associated with long-term survival of peritoneal dialysis patients

Fluid overload is a common complication in peritoneal dialysis (PD) patients. The prognostic importance of enrollment fluid status in long-term PD patients remains to be investigated. The objective of the present study was to investigate the prognostic importance of enrollment fluid status in the long-term survival of PD patients. We enrolled 53 PD patients (mean age: 53 years) from November 2000 to February 2006. On enrollment, demographic, clinical, and biochemical data were recorded. Bioelectrical impedance analysis (BIA) was used to determine the fluid status of PD patients, including extracellular water (ECW), intracellular water (ICW), and total body water (TBW). Fluid status was corrected for body surface area (BSA): ECW-BSA, ICW-BSA, and TBW-BSA respectively. Patients were followed to January 2008. The ECW-BSA correlated negatively with albumin, a marker of nutrition (r = -0.53, p < 0.0001). The ICW/ECW ratio (r = 0.36, p = 0.018) correlated directly and the ECW/ TBW ratio (r = -0.36, p = 0.019) correlated negatively with creatinine. Patients who survived during the study period had a significantly lower ECW-BSA (8.29 L/m2 vs. 9.91 L/m2, p = 0.001) than did those who did not survive. Patients with enrollment ECW-BSA below 9 L/m2 had a significantly better 7-year cumulative survival (Kaplan-Meier) than did patients with a ECW-BSA of 9 L/m2 or more (p = 0.019). Using multivariate Cox regression analysis, adjusting for age, race, diabetes, human immunodeficiency virus (HIV) status, and months on dialysis at enrollment, ECW-BSA was a significant independent predictor of mortality (relative risk: 1.50; p = 0.03). In conclusion, ECW-BSA was a significant independent predictor of long-term survival in PD patients.