Correlation of in vitro cell adhesion, local shear flow and cell density.

Investigating cell adhesion behavior on biocompatible surfaces under dynamic flow conditions is not only of scientific interest but also a principal step towards development of new medical implant materials. Driven by the improvement of the measurement technique for microfluidic flow fields (scanning particle image velocimetry, sPIV), a semi-automatic correlation of the local shear velocity and the cell detachment probability became possible. The functionality of customized software entitled 'PIVDAC' (Particle Image Velocimetry De-Adhesion Correlation) is demonstrated on the basis of detachment measurements using standard sand-blasted titanium implant material. A thermodynamic rate model is applied to describe the process of cell adhesion and detachment. A comparison of the model and our experimental findings, especially in a mild regime, where the shear flow does not simply tear away all cells from the substrate, demonstrates, as predicted, an increase of detachment rate with increasing shear force. Finally, we apply the method to compare experimentally obtained detachment rates under identical flow conditions as a function of cell density and find excellent agreement with previously reported model simulations that consider pure geometrical effects. The demonstrated method opens a wide field of applications to study various cell lines on novel substrates or in time dependent flow fields.

Robust evidence for long-term survival with 90Y radioembolization in chemorefractory liver-predominant metastatic colorectal cancer.

OBJECTIVES: Our aim was to provide further evidence for the efficacy/safety of radioembolization using yttrium-90-resin microspheres for unresectable chemorefractory liver metastases from colorectal cancer (mCRC). METHODS: We followed 104 consecutively treated patients until death. Overall survival (OS) was calculated from the day of the first radioembolization procedure. Response was defined by changes in tumour volume as defined by Response Evaluation Criteria in Solid Tumours (RECIST) v1.0 and/or a ≥30 % reduction in serum carcinoembryonic antigen (CEA) at 3 months. RESULTS: Survival varied between 23 months in patients who had a complete response to prior chemotherapy and 13 months in patients with a partial response or stable disease. Median OS also significantly improved (from 5.8 months to 17.1 months) if response durability to radioembolization extended beyond 6 months. Patients with a positive trend in CEA serum levels (≥30 % reduction) at 3 months post-radioembolization also had a survival advantage compared with those who did not: 15.0 vs 6.7 months. Radioembolization was well tolerated. Grade 3 increases in bilirubin were reported in 5.0 % of patients at 3 months postprocedure. CONCLUSIONS: After multiple chemotherapies, many patients still have a good performance status and are eligible for radioembolization. This single procedure can achieve meaningful survivals and is generally well tolerated. KEY POINTS: • After multiple chemotherapies, many patients are still eligible for radioembolization (RE). • RE can achieve meaningful survival in patients with chemorefractory liver-predominant metastatic colorectal cancer (mCRC). • Tumour responsiveness to prior systemic treatments is a significant determinant of overall survival (OS) after RE. • Radioembolization in patients with a good performance status is generally well tolerated.

Automatic path proposal computation for CT-guided percutaneous liver biopsy.

PURPOSE: To evaluate feasibility of automatic software-based path proposals for CT-guided percutaneous biopsies. METHODS: Thirty-three patients (60 [Formula: see text] 12 years) referred for CT-guided biopsy of focal liver lesions were consecutively included. Pre-interventional CT and dedicated software (FraunhoferMeVis Pathfinder) were used for (semi)automatic segmentation of relevant structures. The software subsequently generated three path proposals in downward quality for CT-guided biopsy. Proposed needle paths were compared with consensus proposal of two experts (comparable, less suitable, not feasible). In case of comparable results, equivalent approach to software-based path proposal was used. Quality of segmentation process was evaluated (Likert scale, 1 [Formula: see text] best, 6 [Formula: see text] worst), and time for processing was registered. RESULTS: All biopsies were performed successfully without complications. In 91 % one of the three automatic path proposals was rated comparable to experts' proposal. None of the first proposals was rated not feasible, and 76 % were rated comparable to the experts' proposal. 7 % automatic path proposals were rated not feasible, all being second choice ([Formula: see text]) or third choice ([Formula: see text]). In 79 %, segmentation at least was good. Average total time for establishing automatic path proposal was 42 [Formula: see text] 9 s. CONCLUSION: Automatic software-based path proposal for CT-guided liver biopsies in the majority provides path proposals that are easy to establish and comparable to experts' insertion trajectories.

Renal Pseudoaneurysms and Arteriovenous Fistulas as a Complication of Nephron-Sparing Partial Nephrectomy: Technical and Functional Outcomes of Patients Treated With Selective Microcoil Embolization During a Ten-Year Period.

PURPOSE: The aim of this study was to evaluate the clinical and functional outcomes in patients who underwent selective interventional embolization of renal pseudoaneurysms or arteriovenous fistulas at our center. MATERIALS AND METHODS: Our retrospective analysis included all consecutive patients who received selective transcatheter embolization of renal pseudoaneurysms or arteriovenous fistulas after partial nephrectomy in our department from January, 2003 to September, 2013. The technical and clinical success rate and functional outcome of every procedure was collected and analyzed. Furthermore, the change in renal parenchymal volume before and after embolization was determined in a subgroup. RESULTS: A total of 1425 patients underwent partial nephrectomy at our hospital. Of these, 39 (2.7 %) were identified with a pseudoaneurysm or an arteriovenous fistula after partial nephrectomy. The diagnosis of the vascular lesions was made by means of biphasic CT or CEUS. Technical success by means of selective microcoil embolization was achieved in all 39 patients (100 %). Clinical success, defined as no need for further operation or nephrectomy during follow-up, was achieved in 35 of 39 patients (85.7 %). Renal function, as measured by eGFR before and after the intervention, did not change significantly. However, a mean loss of parenchymal volume of 25.2 % was observed in a subgroup. No major or minor complications were attributable to the embolization procedure. CONCLUSION: Transcatheter embolization is a promising method for treating vascular complications which may occur after partial nephrectomy. We confirm the high success rate of this technique while discussing renal functional outcomes and potential safety aspects. KEY POINTS: Arterial pseudoaneurysms and arteriovenous fistulas are rare but severe complications after partial nephrectomy. Selective microcoil embolization is a safe and effective kidney-preserving procedure for treating these complications. Embolization leads to a significant loss of renal parenchymal volume but not to a loss of renal function.

Magnetic resonance imaging versus lymphoscintigraphy for the assessment of focal lymphatic transport disorders of the lower limb: first experiences.

PURPOSE: To compare the diagnostic accuracy of magnetic resonance imaging (MR-lymphangiography) and lymphoscintigraphy for assessment of focal lesions of the peripheral lymphatic system. Patients with focal lymphatic transport disorders might benefit from surgi-cal interventions. PATIENTS, METHODS: We examined by lymphoscintigraphy and MR-lymphangiography a total of 85 lower limbs in 46 consecutive patients (33 women; mean age 41 years; range 9-79 years) presenting with uni- or bilateral lymphedema. MR-lymphangiographies were obtained at isotropic sub-millimeter resolution with a 3.0 Tesla magnet after injection of gadolinium contrast medium. MR-lymphangiography was reviewed by radiologists, whereas lymphoscintigraphy was reviewed by nuclear medicine physicians. The images were examined for localization and distribution of any focal lesions of the lymphatic vessel system. Diagnostic accuracy of the MR-approach was calculated relative to the lymphoscintigraphy gold standard. RESULTS: There was substantial correlation of results by the two modalities (κ = 0.62). MR-lymphangiography had sensitivity of 68%, specificity of 91%, positive predictive value of 82%, and negative predictive value of 83%. CONCLUSIONS: Imaging findings of both lymphoscintigraphy and MR-lymphangiography showed good diagnostic accuracy. MR-lymphangiography proved more information about anatomic location of focal lesions of the lymphatic vessels, but use of MR-lymphangiography is currently constrained due to the requirement for off-label subcutaneous injection of gadolinium chelates. Consequently, and due to its superior sensitivity lymphoscintigraphy remains the most common imaging method to assess functional lymphatic disorders of the lower limb.

[Computed tomography angiography as the basis for optimized therapy planning before endovascular aneurysm repair (EVAR)]. / CT-Angiographie als Grundlage der optimierten Therapieplanung vor endovaskulärer Aneurysmaausschaltung (EVAR).

Computed tomography angiography (CTA) of the aorta is an accepted standard diagnostic procedure for preoperative evaluation and planning of endovascular treatment of abdominal aortic aneurysms (endovascular aortic repair EVAR). The CTA method delivers all relevant anatomical and morphological information on the underlying pathology of the aorta and pelvic axes. Various software solutions are available for multiplanar reconstruction of the CT data for exact measurement of the access routes and landing zones and are essential components of individualized operation planning. The synthesis of all CT-based information allows a safe and exactly targeted release of the stent graft in the aorta. Furthermore, the periprocedural radiation dose can be reduced by a precise preoperative planning of the positions to be irradiated during implantation.

[MR lymphangiography for assessment of focal dermal backflow for presurgical work-up in patients with peripheral lymphoedema]. / Die MR-Lymphangiografie in der präoperativen Diagnostik des fokalen "dermal backflow" bei peripheren Lymphödemen.

BACKGROUND: MR lymphangiography might provide valuable morphological information in the diagnosis of peripheral lymphedema in addition to lymphoscintigraphy. Even patients with focal dermal backflow can benefit from surgical intervention. The purpose of this study was to assess the feasibility of MR-Lymphangiography for assessment of focal dermal backflow for pre-surgical work-up. PATIENTS/MATERIALS & METHODS: 50 patients with peripheral lymphedema were included in this study. Patients showing focal dermal backflow in MR-Lymphangiography were reviewed and analyzed separately. The MR findings were correlated to lymphoscintigraphy. Concordance of the 2 modalities regarding existence and distribution of dermal backflow were examined. Furthermore the feeding vessels of the dermal backflow were assessed and visualized. RESULTS: Dermal backflow was diagnosed with MR lymphangiography in 13 patients. Dermal backflow was confirmed by lymphoscintigraphy in 12 patients (92.3%). The feeding vessels of the dermal backflow configuration could be visualized in 9 patients (69.2%) and could be visualized with 3-dimensional reconstructions. The latter is not possible with lymphoscintigraphy. CONCLUSION: MR lymphangiography provides important supplementary diagnostic information in patients with peripheral lymphedema additional to lymphoscintigraphy. Particularly in patients with focal dermal backflow and intended surgery, MR lymphangiography holds high potential for pre-surgical work-up.

Chemical and mechanical impact of silica nanoparticles on the phase transition behavior of phospholipid membranes in theory and experiment.

The interaction of nanoparticles (NPs) with lipid membranes is an integral step in the interaction of NPs and living cells. During particle uptake, the membrane has to bend. Due to the nature of their phase diagram, the modulus of compression of these membranes can vary by more than one order of magnitude, and thus both the thermodynamic and mechanical aspects of the membrane have to be considered simultaneously. We demonstrate that silica NPs have at least two independent effects on the phase transition of phospholipid membranes: 1), a chemical effect resulting from the finite instability of the NPs in water; and 2), a mechanical effect that originates from a bending of the lipid membrane around the NPs. Here, we report on recent experiments that allowed us to clearly distinguish both effects, and present a thermodynamic model that includes the elastic energy of the membranes and correctly predicts our findings both quantitatively and qualitatively.

Breast tumor cell contamination of hematopoietic stem cell collections.

The survival for patients with advanced breast cancer following conventional combination chemotherapy remains limited. Attempts to circumvent drug resistance have involved high-dose chemotherapy along with autologous hematopoietic stem cell support. Despite this, relapse remains the primary cause of death. Breast tumor cells are commonly found in hematopoietic stem cell collections. The role of reinfused occult tumor cells in malignant relapse following high-dose chemotherapy has yet to be determined but is likely to have a negative impact. Strategies to decrease stem cell contamination under investigation include: (1) improved regimens for stem cell mobilization, (2) enhanced techniques for tumor cell detection, (3) targeted tumor cell purging and (4) alternative sources of stem cells. These approaches hold promise for improving the outcome of patients undergoing high-dose chemotherapy and stem cell reinfusion for poor-prognosis breast cancer.

Improved efficiency in providing blood to surgical patients using a novel approach to preadmission testing.

Expansion of the preadmission process for same-day-admit (SDA) surgery patients through our Admissions Evaluation Center has provided an efficient and convenient means for complete patient evaluation up to 30 days in advance of surgery. Traditionally, collection of blood samples for the pretransfusion testing that is necessary to select compatible blood for transfusion occurs within 72 hours of admission, consistent with standards to ensure detection of red blood cell (RBC) alloantibodies formed as a result of recent transfusion or pregnancy. As a result, samples for many SDA patients were submitted Stat the morning of surgery, resulting in an unwieldy amount of testing and delay in blood availability. To address this problem, the time interval for collection of patient blood samples for pretransfusion testing was extended to 30 days prior to surgery. To ensure safety, this change required documentation of patient transfusion and pregnancy history at 2 specific timepoints. Input from a multidisciplinary team was vital to assess the process of blood ordering and administration and to determine the best means to accomplish these steps. Implementation of the new process resulted in a decreased number of emergent requests for compatibility testing, decreased delays in blood delivery, and elimination of canceled surgery due to cases with unexpected RBC antibodies.

Management of chronic myeloid leukemia during pregnancy with leukapheresis.

We describe the successful treatment of a pregnant patient with chronic myelogenous leukemia in chronic phase by using only leukapheresis. Following 20 leukapheresis procedures initiated during the 13th week of gestation and performed over approximately 7 weeks, the patients white blood cell count dropped from 242,000/microl to 19,300/microl. The WBC remained stable over the ensuing 17 weeks until the time of delivery. The patient gave birth by cesarean section to a healthy 2,640 g boy at 37.5 weeks of gestation. This is the second report of the successful use of leukapheresis alone for chronic myelogenous leukemia in chronic phase during the first half of pregnancy. We conclude that where leukapheresis is available, it may provide an alternative treatment to chemotherapy or alpha-interferon, especially in light of their potential teratogenic and leukemogenic side-effects.

Evaluation of LH secretory dynamics during the rat proestrous LH surge.

The preovulatory luteinizing hormone (LH) surge results from the integration of complex interactions among gonadal steroids and hypothalamic and pituitary hormones. To evaluate changes in LH secretory dynamics that occur during the rat LH surge, we have 1) obtained frequently sampled serum LH concentration time series, 2) used both waveform-dependent and waveform-independent convolution analyses, and 3) independently assessed proestrous LH half-life and basal non-gonadotropin-releasing hormone (GnRH)-dependent LH secretion during the LH surge. Waveform-independent pulse analysis revealed a 24-fold increase in the maximal pulsatile LH secretory rate attained during late proestrus compared with early proestrus. A 15-fold increase was quantified for the mean LH secretory rate. In complementary analyses, we applied a measured LH half-life of 17 +/- 2.7 min and a median basal LH secretion rate of 0.0046 microgram. l-1. min-1 for convolution analysis, revealing a 16-fold increase in the mass of LH released/burst and more than sixfold rise in the amplitude of the secretory peaks. Evaluation of the approximate entropy of the LH surge profiles was performed, showing an increase in the orderliness of the LH release process during the surge. We conclude that both quantitative (mass/burst) and qualitative (approximate entropy) features of LH release are regulated during the proestrous LH surge.

Activated protein C resistance assay performance: improvement by sample dilution with factor V-deficient plasma.

OBJECTIVE: To evaluate a modification of a commercially available reagent kit (COATEST APC Resistance Kit) for functional activated protein C (APC) resistance testing, and to determine the ability of the modified assay to demonstrate APC resistance in patients receiving warfarin. DESIGN: Functional APC resistance testing was performed using both the first-generation COATEST APC Resistance Kit and a modified, or second-generation, version of the COATEST assay that uses predilution of the patient sample with factor V-deficient plasma. Factor V genotyping for APC resistance (FV R506Q) was performed using a well-characterized polymerase chain reaction-restriction fragment length polymorphism method. SETTING: University medical center. PATIENTS: Seventy-three individuals referred for hypercoagulability testing who were not receiving warfarin therapy and 29 patients with a history of venous thrombosis who were receiving warfarin therapy. MAIN OUTCOME MEASURE: Sensitivity and specificity as determined by comparing functional APC resistance to the FV R506Q genotype. RESULTS: In 73 patients referred for hypercoagulability testing, but not receiving warfarin therapy, a sensitivity of 0.86 and a specificity of 0.75 were obtained with the first-generation COATEST assay. In contrast, a sensitivity and specificity of 1.0 were obtained when the second-generation COATEST assay was employed. In 29 patients receiving warfarin, the first-generation assay exhibited a sensitivity and specificity of 0.88 and 0.95, respectively, whereas the sensitivity and specificity for the second-generation assay was 1.0. CONCLUSIONS: Predilution of patient plasma with factor V-deficient plasma results in improved sensitivity and specificity of the COATEST APC Resistance Kit, thus offering a simple modification to enhance APC resistance determination in the routine clinical laboratory setting.

Resistance to Activated Protein C: Comparison of Three Different PCR Methods for Detection FV R506Q.

Background: Resistance to activated protein C(APC) is the most prevalent identifiable risk factor for inherited thrombophilia. Over 90% of APC resistance results from a single point mutation in the Factor V gene. The mutation, termed FV R506Q of FV Leiden, predicts an abnormal Factor Va protein in which arginine, at amino acid position 506, is replaced by glutamine, rendering Factor Va resistant to proteolytic inactivation by APC, thus establishing a life long hypercoagulable state. The current study compared three different polymerase chain reaction (PCR)-based approaches for the detection of FV R506Q. Methods and Results: Sixty-seven patient blood samples were genotyped by (1) analyzing for loss of a Mnl I recognition site, an acquired restriction-fragment-length polymorphism (RFLP) due to FV R506Q; (2) primer-engineered RFLP wherein the presence of FV R506Q results in generation of a novel Nla III recognition site; and (3) allele-specific PCR. Sixty-five of 67 patient samples yielded concordant genotype results by all three PCR methods. Of the remaining 2 of the 67 patients, a "nondiagnostic" result was obtained for either allele-specific PCR or primer-engineered RFLP. Conclusions: A comparative analysis of 67 patient samples demonstrated that primer engineered RFLP and allele-specific PCR offer feasible alternative or confirmatory testing approaches to Mnl I RFLP for the detection of FV R506Q. A high degree of diagnostic concordance was observed for all three methods, and no false positive or negative results were observed with the Mnl I RFLP technique.

Differential gonadotropin responses to N-methyl-D,L-aspartate in metestrous, proestrous, and ovariectomized rats.

Peripheral administration of N-methyl-D,L-aspartate (NMA), an analogue of the excitatory amino acid aspartate, elicits LH and prolactin (PRL) release in rats, most likely by increasing endogenous releasing-hormone secretion. These experiments were carried out to assess the degree to which NMA stimulates FSH and to analyze the relationship between endocrine status and responsiveness to NMA in female rats, in contrast to male rats, as described in the companion paper [Biol Reprod 48:000-000]. In experiment 1, estrous rats (n = 10) and diestrous rats (n = 10) and in experiment 2, estrous rats (n = 11) and rats ovariectomized (OVX) 8 days previously (n = 10) were fitted with atrial catheters and injected s.c. with 100 micrograms of an LHRH antagonist or vehicle at 2100 h. Starting at 0900 h the next day (metestrus, proestrus, or Day 9 post-OVX), blood was withdrawn every 10 min for 3 h. Each animal received i.v. 5 mg NMA after the first hour and i.v. 500 ng LHRH after the second hour. NMA significantly increased LH in metestrous and proestrous females, and LHRH antagonist blunted the increases. In OVX females, LH decreased after NMA. FSH was not affected by NMA in any group. PRL increased after NMA in proestrous and metestrous animals. LHRH caused surge-like LH and small FSH increases in vehicle groups; these increases did not differ in amplitude between intact and OVX animals and were blunted by pretreatment with LHRH antagonist. In experiment 3, 10 diestrous rats were fitted with atrial catheters and were serially bled at 2-h intervals from 1200 h on the following day (proestrus) until 0600 h on estrus morning. After the first sample the animals were injected s.c. with 0.2 mg/kg MK801, a noncompetitive NMA receptor antagonist, or with saline. Four of the 5 saline-treated animals exhibited surges of LH and FSH as well as elevated progesterone levels, with LH and progesterone peaking at 2000 h. Five of 5 MK801-treated animals failed to have elevated LH, FSH, or progesterone levels at any time point. These data demonstrate that LHRH mediates the LH response to NMA in rats and that endogenous NMA receptor binding may be necessary for the preovulatory gonadotropin surges. The lack of FSH responses to NMA during periods of low-level gonadotropin secretion suggests that physiological increments in endogenous LHRH secretion sufficient to induce a pulse of LH are insufficient to stimulate pulse-like FSH release.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential gonadotropin responses to N-methyl-D,L-aspartate in intact and castrated male rats.

Peripheral administration of N-methyl-D,L-aspartate (NMA), a neuroexcitatory amino acid agonist, probably stimulates LH release through an increase in endogenous LHRH secretion. In the present study, NMA and a potent LHRH antagonist were used to determine the degree to which release of FSH is similarly dependent upon the acute secretion of LHRH. A second aim was to compare responsiveness of LHRH neurons to NMA in castrated and intact male rats. Adult male rats were castrated (n = 10) or sham castrated (n = 11) on the morning of Day 0. After 8 days, rats were fitted with atrial catheters between 0900 and 1200 h; at 2100 h they received s.c. either oil vehicle or 100 micrograms of an LHRH antagonist. Starting at 0900 h on Day 9, 0.5-ml blood samples were collected every 10 min for 3 h. After 1 h of sampling each animal received i.v. 5 mg of NMA in 0.5 ml 0.9% saline. An hour later each rat received i.v. 500 ng of LHRH in 0.5 ml saline. Plasma LH, FSH, and prolactin (PRL) levels were determined by RIA. In the oil-treated sham castrates, mean plasma LH levels were increased by 110% (p < 0.01) within 10 min and remained elevated for 30 min after the injection of NMA. The profile of this LH secretory response was similar to or slightly more robust than endogenous LH pulses observed previously. The NMA-induced LH release was completely blocked by pretreatment with LHRH antagonist. In both oil- and antagonist-treated sham-castrated rats, NMA administration failed to elicit a concomitant increase in plasma FSH levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Neuroendocrine regulation of the luteinizing hormone-releasing hormone pulse generator in the rat.

We have analyzed the mechanisms by which several known regulators of the LHRH release process may exert their effects. For each, we have attempted to determine how and where the regulatory input is manifest and, according to our working premise, we have attempted to identify factors which specifically regulate the LHRH pulse generator. Of the five regulatory factors examined, we have identified two inputs whose primary locus of action is on the pulse-generating mechanism--one endocrine (gonadal negative feedback), and one synaptic (alpha 1-adrenergic inputs) (see Fig. 29). Other factors which regulate LHRH and LH release appear to do so in different ways. The endogenous opioid peptides, for example, primarily regulate LHRH pulse amplitude (Karahalios and Levine, 1988), a finding that is consistent with the idea that these peptides exert direct postsynaptic or presynaptic inhibition (Drouva et al., 1981). Gonadal steroids exert positive feedback actions which also result in an increase in the amplitude of LHRH release, and this action may be exerted through a combination of cellular mechanisms which culminate in the production of a unique, punctuated set of synaptic signals. Gonadal hormones and neurohormones such as NPY also exert complementary actions at the level of the pituitary gland, by modifying the responsiveness of the pituitary to the stimulatory actions of LHRH. The LHRH neurosecretory system thus appears to be regulated at many levels, and by a variety of neural and endocrine factors. We have found examples of (1) neural regulation of the pulse generator, (2) hormonal regulation of the pulse generator, (3) hormonal regulation of a neural circuit which produces a unique, punctuated synaptic signal, (4) hormonal regulation of pituitary responsiveness to LHRH, and (5) neuropeptidergic regulation of pituitary responsiveness to LHRH. While an attempt has been made to place some of these regulatory inputs into a physiological context, it is certainly recognized that the physiological significance of these mechanisms remains to be clarified. We also stress that these represent only a small subset of the neural and endocrine factors which regulate the secretion or actions of LHRH. A more comprehensive list would also include CRF, GABA, serotonin, and a variety of other important regulators. Through a combination of design and chance, however, we have been able to identify at least one major example of each type of regulatory mechanism.