Plasma Ultrafiltrate Research Articles

Non-voltage-gated Ca2+ channel signaling in glomerular cells in kidney health and disease.

Positioned at the head of the nephron, the renal corpuscle generates a plasma ultrafiltrate to initiate urine formation. Three major cell types within the renal corpuscle, the glomerular mesangial cells, podocytes, and glomerular capillary endothelial cells, communicate via endocrine- and paracrine-signaling mechanisms to maintain the structure and function of the glomerular capillary network and filtration barrier. Ca2+ signaling mediated by several distinct plasma membrane Ca2+ channels impacts the functions of all three cell types. The past two decades have witnessed pivotal advances in understanding of non-voltage-gated Ca2+ channel function and regulation in the renal corpuscle in health and renal disease. This review summarizes the current knowledge of the physiological and pathological impact of non-voltage-gated Ca2+ channel signaling in mesangial cells, podocytes and glomerular capillary endothelium. The main focus is on transient receptor potential and store-operated Ca2+ channels, but ionotropic N-methyl-d-aspartate receptors and purinergic receptors also are discussed. This update of Ca2+ channel functions and their cellular signaling cascades in the renal corpuscle is intended to inform the development of therapeutic strategies targeting these channels to treat kidney diseases, particularly diabetic nephropathy.

Pericarditis. Causes, Mechanisms of Development, Variants of Course and Therapeutic Approaches in Modern Conditions

Under physiological conditions, the pericardial cavity contains serous fluid (15-50 ml), which belongs to the plasma ultrafiltrate and is visualized during echocardiography only in systole. The thickness of the pericardium in an adult averages 2 mm (1-3 mm). Inflammatory lesions of the pericardium with or without effusion into its cavity can act as an independent disease, and as a secondary manifestation of another pathological condition. Pericarditis of infectious (14-16%) and non-infectious (15-20%) nature, primary and secondary, acute, chronic and recurrent are commonly distinguished. The prevalence of acute and idiopathic recurrent pericarditis is 27.7 per 100,000 population and 5.4-8.1 per 100,000 population, respectively. Currently, idiopathic recurrent pericarditis belongs to polygenic autoinflammatory diseases, where an important role in the initiation of the pathologic process belongs to the inflammatory cytokine — interleukin-1 (β and α). The most characteristic manifestations of acute pericarditis are chest pain, dyspnea and fever. The article summarizes the main aspects of etiology, clinical manifestations, diagnosis and therapy of pericarditis, including the peculiarities of its treatment taking into account specific conditions. A clinical case demonstrated a case of acute effusion pericarditis with recurrence, which was characterized by rapid progression of heart failure symptoms, as well as systemic manifestations (anemia, hypercytokinemia, marked muscle weakness). The results of echocardiography allowed to identify the presence of pericardial effusion. Steroid and non-steroidal anti-inflammatory, anticoagulant and antibacterial therapy led to the disappearance of pericardial effusion and normalization of the activity of inflammatory markers in serum. However, in the dynamics of observation the attempt to suspend glucocorticoid therapy again led to fluid accumulation in the pericardium, which required continuation of steroidal and non-steroidal anti-inflammatory drugs.

Determination of furosemide and its glucuronide metabolite in plasma, plasma ultrafiltrate and urine by HPLC-MS/MS with application to secretion and metabolite formation clearances in non-pregnant and pregnant women

Furosemide (FUR) has been used in probe drugs cocktails for in vivo evaluation of the renal transporters OAT1 and OAT3 activities in studies of drug-drug interactions (generally using probenecid as an inhibitor) and drug-disease interactions. The objective of this study was to develop and validate methods for FUR and its glucuronide metabolite (FUR-GLU) analysis in plasma, plasma ultrafiltrate and urine for application in pharmacokinetics studies: a pilot drug-drug interaction study in pregnant women (n = 2), who received a single oral dose of FUR (40 mg) and in another occasion a single oral dose of probenecid (750 mg) before a single oral dose of FUR (40 mg), and in non-pregnant women participants (n = 12), who only received a single oral dose of FUR (40 mg). The samples preparation for FUR in 50 µL of plasma and plasma lysate were carried by acidified liquid-liquid extraction, while 50 µL of urine and 200 µL of plasma ultrafiltrate were simply diluted with the mobile phase. The methods presented linearities in the range of 0.50 – 2500 ng/mL of plasma and plasma lysate, 0.125 – 250 ng/mL of plasma ultrafiltrate, and 50 – 20,000 ng/mL of urine. FUR-GLU methods presented linearities in the range of 0.125 – 250 ng/mL of plasma ultrafiltrate and 50 – 20,000 ng/mL of urine. Precision and accuracy evaluations showed coefficients of variation and relative errors < 15%. In the pregnant women participants, the mean values of FUR CLrenal, CLsecretion, CLformation. FUR-GLU and CLnon-renal were all reduced when probenecid was administered with FUR (8.24 vs 2.89 L/h, 8.15 vs 2.80 L/h, 3.86 vs 1.75 L/h, 48.26 vs 22.10 L/h, respectively). Non-pregnant women presented similar values of FUR CLrenal, CLsecretion, CLformation. FUR-GLU to the pregnant women who received FUR only. Finally, FUR fraction unbound (fu) resulted in values of approximately 1% in pregnant women and to 0.22% in non-pregnant women. These developed and validated methods for FUR and FUR-GLU quantification in multiple matrices can allow the further investigation of UGT1A9/1A1 and the fu when FUR is administered as an OAT 1 and 3 in vivo probe.

Using HPLC for the determination of platinum drugs in biological matrixes after derivatization with diethyldithiocarbamate.

Challenges and pitfalls in the application of diethyldithiocarbamate derivatization for LC analysis of cisplatin and oxaliplatin, as well as the suitability of this method for different biological matrices with implications for use in routine practice have been identified. The LC of platinum drugs presents a significant challenge. They are polar compounds with poor retention on reverse phase packings. Cisplatin also exhibits poor absorption in UV and ionization in mass spectrometry. Therefore, we developed and optimized a derivatization approach for the LC analysis of total platinum in plasma, plasma ultrafiltrate, peritoneal fluid, and urine. Derivatization in urine proved to be difficult due to the complexity of the matrix, and extended testing was required. Our results highlight the important issues affecting the efficiency, reliability, and suitability of platinum drug derivatization. Although precolumn derivatization is less selective than its postcolumn counterpart, the application of precolumn derivatization is a simple, rapid, and universal approach for the determination of platinum drugs by HPLC. One of its major advantages is that it allows a more affordable analysis using UV detection without the need for additional high-end instrumentation such as a MS detector.

Evaluation of small extracellular vesicles as biomarkers of efficacy with anti-PD-1 mAb therapy in patients with recurrent/metastatic HNSCC.

6042 Background: The development of biomarkers that reliably predict response to anti-PD-1 mAb therapy (IO) is a critical need. Small (30-150 nm) extracellular vesicles (sEV), aka exosomes, are “molecular mimics” of their parent cells. In cancer, plasma sEV are mixtures of tumor-derived exosomes (TEX) and vesicles produced by non-malignant cells. We conducted a retrospective study of R/M HNSCC patients treated with IO to evaluate sEV as predictive biomarkers. Methods: We evaluated sEV in plasma of R/M HNSCC patients (n = 24) obtained just prior to initiation of IO. Precleared ultrafiltered plasma was used to isolate total plasma sEV by size exclusion chromatography. Total plasma sEV were separated into two subsets, T cell-derived CD3(+) sEV and TEX-enriched CD3(-) sEV by immunocapture with anti-CD3 mAb. On-bead flow cytometry was used to estimate relative levels of proteins carried on the sEV surface. Specifically, the CD3(-) fraction was evaluated for stimulatory (stim; CD40, CD40L, OX40, OX40L, CD80) and suppressive (supp; TGFb, CTLA4, FasL, PD-L1, PD-1) proteins. Differences between responders (CR/PR/SD) and non-responders (PD) were assessed using Wilcoxon-Mann-Whitney test. Multivariate Cox proportional hazards regression was used to evaluate the relationship between the pre-treatment sEV characteristics and outcome. Results: Mean age was 62, 46% had oropharynx (82% HPV+), 17% oral cavity and 29% had larynx/hypopharynx primary. Treatment indication for IO was 46% platinum failure, remainder first line. Best response: 17% PR, 29% SD, and 54% PD. Median PFS and OS were 5.3 and 16.2 months, respectively. Total sEV protein level was not associated with efficacy. Total CD3(+) sEV level was low overall and did not correlate with lymphocyte count or neutrophil/lymphocyte ratio. High CD3(+) sEV level was associated with better OS [HR: 0.16 (95% CI 0.04-0.59), P = 0.007] and PFS [HR: 0.16 (95% CI 0.04-0.58), P = 0.005] but not response. While total TEX and levels of individual stim and supp proteins carried by TEX were not predictive of response, an increased supp/stim ratio was (P = 0.02). Importantly, high TEX supp score and stim score were both associated with better OS [HR: 0.19 (95% CI 0.05-0.77), P = 0.02, and HR: 0.26 (95% CI 0.07-0.95), P = 0.04, resp.]. High PD-L1, but not PD-1 on TEX, was associated with better OS [HR: 0.15 (95% CI 0.04-0.56), P = 0.005]; and PFS: HR: 0.33 (95% CI 0.11-0.94), P = 0.04]. Conclusions: Evaluation of two sEV subsets, T cell-derived-CD3(+) sEV and TEX-enriched CD3(-) sEV, indicated their potential utility as predictive biomarkers with IO. High T cell-derived sEV, TEX supp/stim ratio, and TEX PD-L1 expression levels were independently associated with significantly increased efficacy with IO. Our study uniquely analyzed the predictive value of plasma sEv subsets in IO treated R/M HNSCC patients, and evaluation in a larger cohort is warranted.

Determination of Indolepropionic Acid and Related Indoles in Plasma, Plasma Ultrafiltrate, and Saliva

The microbial metabolite indolepropionic acid (IPA) and related indolic metabolites, including indolecarboxylic acid (ICA), indolelactic acid (ILA), indoleacetic acid (IAA), indolebutyric acid (IBA), indoxylsulfate (ISO4), and indole, were determined in human plasma, plasma ultrafiltrate (UF), and saliva. The compounds were separated on a 150 × 3 mm column of 3 μm Hypersil C18 eluted with a mobile phase of 80% pH 5 0.01 M sodium acetate containing 1.0 g/L of tert-butylammonium chloride/20% acetonitrile and then detected fluorometrically. Levels of IPA in human plasma UF and of ILA in saliva are reported for the first time. The determination of IPA in plasma UF enables the first report of free plasma IPA, the presumed physiologically active pool of this important microbial metabolite of tryptophan. Plasma and salivary ICA and IBA were not detected, consistent with the absence of any prior reported values. Observed levels or limits of detection for other indolic metabolites usefully supplement limited prior reports.

Development and Validation of the New Liquid Chromatography-Tandem Mass Spectrometry Method for the Determination of Unbound Tacrolimus in the Plasma Ultrafiltrate of Transplant Recipients

(1) Background: Only unbound tacrolimus particles are considered to be active and capable of crossing cellular membranes. Thus, the free-drug concentration might be better associated with clinical effects than the total drug concentration used for dosage adjustment. We propose a new, fully validated online liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for unbound tacrolimus concentration measurement. (2) Methods: The determination of the unbound tacrolimus concentration in plasma ultrafiltrate was performed with the Nexera LC system with LCMS-8050 triple quadrupole MS using ascomycin as an internal standard. Chromatographic separation was made using a HypurityC18 analytical column. MS/MS with electrospray ionization and positive-ion multiple-reaction monitoring was used. The unbound tacrolimus level was determined in 36 patients after solid organ transplantation (n = 140). (3) Results: A lower limit of quantification 0.1 pg/mL was achieved, and the assay was linear between 0.1 and 20 pg/mL (R2 = 0.991). No carry-over was detected. The within-run and between-run accuracies ranged between 97.8–109.7% and 98.3–107.1%, while the greatest imprecision was 10.6% and 10.7%, respectively. Free tacrolimus in patients’ plasma ultrafiltrate varied between 0.06 and 18.25 pg/mL (median: 0.98 pg/mL). (4) Conclusions: The proposed method can be easily implemented. The significance of the unbound tacrolimus concentration needs to be investigated. This may facilitate the individualization and optimization of immunosuppressive treatment.

A separate assay of released and liposomal encapsulated eribulin in dog plasma by liquid chromatography with tandem mass spectrometry for its application to a pharmacokinetic study.

Eribulin has been used as a drug for the treatment of metastatic breast cancer and liposomal formulation of eribulin is under development to achieve a wider therapeutic index. It is important to separately determine released and encapsulated drugs in systemic circulation for liposomal drugs. In this study, a separate assay method was developed for the determination of released and total (encapsulated + released) eribulin concentrations in dog plasma by liquid chromatography with tandem mass spectrometry. The released eribulin in dog plasma was separated by ultrafiltration of plasma samples. Obtained plasma ultrafiltrate and untreated plasma samples recognized as released and total eribulin, respectively, were subjected to protein precipitation for extraction of eribulin. Eribulin was quantifiable from 0.1ng/mL. Accuracy and precision of eribulin in both matrices were within±15 and 15%, respectively, indicating a robust assay. Released and total eribulin concentrations in plasma were determined after intravenous administration of the liposomal formulation of eribulin to dogs, resulting in minimal released eribulin in plasma. In conclusion, a robust method for released and total eribulin levels in dog plasma was developed and was successfully applied to a pharmacokinetic study in dogs to characterize the pharmacokinetic profiles.

Sensitive LC-MS/MS Methods for Amphotericin B Analysis in Cerebrospinal Fluid, Plasma, Plasma Ultrafiltrate, and Urine: Application to Clinical Pharmacokinetics.

Neurocryptococcosis, a meningoencephalitis caused by Cryptococcus spp, is treated with amphotericin B (AmB) combined with fluconazole. The integrity of the brain-blood barrier and the composition of the cerebrospinal fluid (CSF) may change due to infectious and/or inflammatory diseases such as neurocryptococcosis allowing for the penetration of AmB into the central nervous system. The present study aimed to develop LC-MS/MS methods capable of quantifying AmB in CSF at any given time of the treatment in addition to plasma, plasma ultrafiltrate, with sensitivity compatible with the low concentrations of AmB reported in the CSF. The methods were successfully validated in the four matrices (25 μl, 5–1,000 ng ml−1 for plasma or urine; 100 μl, 0.625–250 ng ml−1 for plasma ultrafiltrate; 100 μl, 0.1–250 ng ml−1 for CSF) using protein precipitation. The methods were applied to investigate the pharmacokinetics of AmB following infusions of 100 mg every 24 h for 16 days administered as a lipid complex throughout the treatment of a neurocryptococcosis male patient. The methods allowed for a detailed description of the pharmacokinetic parameters in the assessed patient in the beginning (4th day) and end of the treatment with AmB (16th day), with total clearances of 7.21 and 4.25 L h−1, hepatic clearances of 7.15 and 4.22 L h−1, volumes of distribution of 302.94 and 206.89 L, and unbound fractions in plasma ranging from 2.26 to 3.25%. AmB was quantified in two CSF samples collected throughout the treatment with concentrations of 12.26 and 18.45 ng ml−1 on the 8th and 15th days of the treatment, respectively. The total concentration of AmB in plasma was 31 and 20 times higher than in CSF. The unbound concentration in plasma accounted for 77 and 44% of the respective concentrations in CSF. In conclusion, the present study described the most complete and sensitive method for AmB analysis in plasma, plasma ultrafiltrate, urine, and CSF applied to a clinical pharmacokinetic study following the administration of the drug as a lipid complex in one patient with neurocryptococcosis. The method can be applied to investigate the pharmacokinetics of AmB in CSF at any given time of the treatment.

Is age-related worsening in ovarian cancer prognosis linked to changes in body composition and pharmacokinetics?

e17553 Background: The prognosis of ovarian cancer worsens markedly with age. Yet few data are available to explain this phenomenon. Two hypotheses can be made. Changes in pharmacokinetics and treatment tolerance limit the dosing of chemotherapy. And/or changes in tumor and host-tumor biology limit treatment efficacy. Methods: We conducted a prospective cohort study of women with stage III/IV high-grade serous ovarian cancers treated with neoadjuvant intravenous carboplatin(C) AUC 5 every 3 weeks and paclitaxel(P) dosed either weekly at 80 mg/m2 or every 3 weeks at 175 mg/m2. Body composition was assessed using baseline CT scans at the L3 level. Total muscle mass, total fat mass, skeletal muscle index (SMI) and fat index were computed. Plasma concentrations were collected at pre-established time points for both C1D1 of C and P and concentration-time data was analyzed by non-compartmental methods. Area under the curve (AUC)0-INF, volume of distribution(Vd), clearance (Cl), half-life, and mean residence time were calculated. Free C concentrations were determined in plasma ultrafiltrate and assayed, along with P plasma concentrations, by liquid chromatography-tandem mass spectrometry. Toxicity was assessed as first cycle nadir ANC and G4 hematologic(H) or grade 3-4 non-hematologic(NH) toxicity by CTCAE 4.0 criteria over a 3 cycles follow-up. The correlation between continuous measures was assessed by Spearman correlation coefficient, and the association with toxicity was evaluated by Wilcoxon rank sum test. Results: Seventeen patients, ages 38 to 86 (median 61) were eligible. All patients but one received 3 cycles of chemotherapy and median dose intensity was 100% (range 33.3-100%). Mean 1st cycle nadir ANC was 1.29 (range 0.06-9.0). 10/17 (59%) patients experienced G4 H and/or G3-4 NH toxicity. SMI was associated with C AUC (r -0.50, p &lt; 0.05), and both total muscle (r = 0.61) and total fat (r = 0.53) were associated with C Vd. We did not find a correlation of P pharmacokinetics with body composition. A lower SMI was associated with 1st cycle G4H toxicity (p = 0.02), while C AUC had a borderline trend only (p = 0.15). Age was associated with a lower Vd (r -0.63, p = 0.009) and Cl (r -0.67, p = 0.004) of C. There was no significant age trend in the body composition parameters. Conclusions: Neoadjuvant treatment delivery was high in an academic setting. Toxicity appeared driven by low skeletal muscle index, in part via affecting carboplatin pharmacokinetics, and showed no significant age trend. The explanation for age-related changes in prognosis is more likely to lay with changes in tumor and host-tumor biology, which are being analyzed.

Metabolomic analysis of uremic pruritus in patients on hemodialysis.

Pruritus is a common debilitating symptom experienced by hemodialysis patients. Treatment is difficult because the cause of uremic pruritus is not known. This study addressed the hypothesis that pruritus is caused by solutes that accumulate in the plasma when the kidneys fail. We sought to identify solutes responsible for uremic pruritus using metabolomic analysis to compare the plasma of hemodialysis patients with severe pruritus versus mild/no pruritus. Pruritus severity in hemodialysis patients was assessed using a 100-mm visual analogue scale (VAS), with severe pruritus defined as >70 mm and mild/no pruritus defined as <10 mm. Twelve patients with severe pruritus (Itch) and 24 patients with mild/no pruritus (No Itch) were included. Pre-treatment plasma and plasma ultrafiltrate were analyzed using an established metabolomic platform (Metabolon, Inc.). To identify solutes associated with pruritus, we compared the average peak area of each solute in the Itch patients to that of the No Itch patients using the false discovery rate (q value) and principal component analysis. Dialysis vintage, Kt/Vurea, and serum levels of calcium, phosphorus, PTH, albumin, ferritin, and hemoglobin were similar in the Itch and No Itch patients. Metabolomic analysis identified 1,548 solutes of which 609 were classified as uremic. No difference in the plasma or plasma ultrafiltrate levels of any solute or group of solutes was found between the Itch and No Itch patients. Metabolomic analysis of hemodialysis patients did not reveal any solutes associated with pruritus. A limitation of metabolomic analysis is that the solute of interest may not be included in the metabolomic platform’s chemical library. A role for uremic solutes in pruritus remains to be established.

Pharmacokinetics and pharmacodynamics integration of danofloxacin against Eschrichia coli in piglet ileum ultrafiltration probe model

Improper use of antibiotics results in poor treatment and severe bacterial resistance. In this study, ultrafiltration probes were successfully placed in the ileum of piglets with the aid of anesthetic. After the fluoroquinolone antimicrobial drug danofloxacin (DAN) was intramuscularly administered, blood and ileum ultrafiltrate were collected at different time points and then determined by High Performance Liquid Chromatography (HPLC). Pharmacokinetics (PK) parameters for plasma and ileum ultrafiltrate were calculated by WinNonlin software. The DAN concentration in ileum ultrafiltrate was much higher than that in plasma during the period 1.2–48 h. The DAN concentration in plasma reached its maximum at 1.10 ± 0.03 h, but reached at 6.00 ± 0.00 h in the ileum ultrafiltrate. The mean Cmax of the ileum is 13.59 times that of plasma. The elimination half-life (T1/2β) in the ileum ultrafiltrate (6.84 ± 1.49 h) was shorter than those in plasma (7.58 ± 3.20 h). The MIC, MBC and MPC of DAN in MH broth against Escherichia coli (O158) were 0.5 µg/mL, 0.5 µg/mL and 4 µg/mL, respectively. Both in vitro and ex vivo kill curves indicated that the killing mechanism of DAN against E. coli is concentration-dependent. The AUC/MPC ratio is 21.33 ± 2.14. Mean PK/PD index (AUC24h/MIC) for ileum ultrafiltrate that achieved bacteriostatic, bactericidal, and eradication were 99.85, 155.57, and 218.02 h, respectively. Three different dosages (1.49 mg/kg, 2.42 mg/kg, and 3.24 mg/kg) were calculated respectively based on AUC24h/MIC ratio above, which might provide a novel approach to the rational design of dosage schedules.

Ovarian follicular fluid: an innovative approach to assess internal dose for reproductive epidemiology

Ovarian follicular fluid serves as a biological window revealing metabolic processes in the microenvironment of a maturing oocyte, and so may offer a more accurate biomarker of biologically effective dose than more traditional compartments, such as blood and urine. Investigators have measured myriad environmental pollutants in ovarian follicular fluid (FF), including toxic trace elements. As a plasma ultrafiltrate, FF content reflects both blood concentrations and in situ physiology. Evidence suggests substantial follicle-to-follicle variability in the concentrations of some analytes, necessitating a “one follicle-one oocyte” approach for investigating associations between exposure and reproductive endpoints. We collected individual FF specimens from up to four follicles, two from each ovary, among 56 women undergoing in vitro fertilization (IVF) with fresh embryo transfer. We determined toxic trace element concentrations using inductively coupled plasma with tandem mass spectrometry (ICP-MS/MS) and linked individual oocytes and embryos to the corresponding FF specimen. We used linear mixed regression models to evaluate associations between natural log transformed FF As, Cd, Pb, and Hg as predictors of IVF outcomes, adjusted for other toxic trace elements, age, race, smoking, and seafood consumption. Median FF As (0.34 μg/L), Cd (27.3 ng/L), Pb (0.06 μg/L), and Hg (0.34 μg/L) concentrations were similar to or lower than those reported previously. Greater FF Cd was associated with a lower probability for a symmetric embryo per 1 ng/L (RR=0.36, 95%CI: 0.17-0.76). Greater FF Pb (1 μg/L) was associated with lower probabilities for a fertilized oocyte per 1 μg/L (RR=0.56, 95%CI=0.25-1.24), although the association was non-linear, and with live birth per 1 μg/L (RR=0.72, 95%CI: 0.53-0.99). Greater Hg was associated with a lower probability of implantation per 1 μg/L (RR=0.31, 95%CI: 0.09-1.06), although the association was non-linear. Our results suggest that FF toxic trace elements may affect IVF outcomes, including live birth, even at comparatively low doses.

Evaluation of the pharmacokinetic drug-drug interaction potential of iohexol, a renal filtration marker.

Carboplatin dose is calculated based on kidney function, commonly estimated with imperfect creatinine-based formulae. Iohexol is used to measure glomerular filtration rate (GFR) and allows calculation of a more appropriate carboplatin dose. To address potential concerns that iohexol administered during a course of chemotherapy impacts that therapy, we performed in vitro and in vivo pharmacokinetic drug-drug interaction evaluations of iohexol. Carboplatin was administered IV to female mice at 60mg/kg with or without iohexol at 300mg/kg. Plasma ultrafiltrate, kidney and bone marrow platinum was quantitated by atomic absorption spectrophotometry. Paclitaxel microsomal and gemcitabine cytosolic metabolism as well as metabolism of CYP and UGT probes was assessed with and without iohexol at 300µg/mL by LC-MS/MS. In vivo carboplatin exposure was not significantly affected by iohexol co-administration (platinum AUC combination vs alone: plasma ultrafiltrate 1,791 vs 1920µg/mL min; kidney 8367 vs 9757µg/g min; bone marrow 12.7 vs 12.7µg/mg-protein min). Paclitaxel microsomal metabolism was not impacted (combination vs alone: 6-α-OH-paclitaxel 38.3 versus 39.4ng/mL/60min; 3-p-OH-paclitaxel 26.2 versus 27.7ng/mL/60min). Gemcitabine human cytosolic elimination was not impacted (AUC combination vs gemcitabine alone: dFdU 24.1 versus 23.7µg/mL/30min). Iohexol displayed no relevant inhibition of the CYP and UGT enzymes in human liver microsomes. Iohexol is unlikely to affect the clinical pharmacokinetics of carboplatin, paclitaxel, gemcitabine, or other agents used in combination with carboplatin treatment. Measuring GFR with iohexol to better dose carboplatin is unlikely to alter the safety or efficacy of chemotherapy through pharmacokinetic drug-drug interactions.

Cerebrospinal fluid dynamics with its surgical implications

Cerebrospinal fluid (CSF) is largely (70-80%) produced by the choroids plexus of the ventricles and is considered as the plasma ultrafiltrate. While CSF formation, circulation, and composition appear to be physiological and physical, its absorption appears to be mainly physical. The formation, composition, circulation, absorption, and changes in pathological conditions of CSF are discussed briefly in this review article. The CSF pressure dynamics studies provide information about the tightness, elastance, or outflow resistance of the CSF in the CNS. We believe that the present study shall help to provide essential details of CSF physiology which are important to many disciplines including radiology, neurology, and neurosurgery.

Immunohistochemical Profiles of Matrix Metalloproteinases and Vascular Endothelial Growth Factor Overexpression in the Antoni B Area of Vestibular Schwannomas

To evaluate the clinical manifestations of cystic vestibular schwannomas (VSs), investigate the immunohistochemical profiles of matrix metalloproteinases (MMPs) and vascular endothelial growth factor (VEGF) expression in Antoni A and B areas, and speculate the pathogenesis of cystic formation and intratumoral hemorrhage. Clinical features and outcomes of 24 cases of cystic VSs and 38 cases of solid VSs were retrospectively compared. Immunohistochemical studies were conducted to evaluate the characteristics of MMPs and VEGF in cystic and solid VSs. The tumor size was 38.92 ± 1.86 mm and 31.95 ± 1.74 mm in the cystic and solid VSs group, respectively (P= 0.011). Cystic VSs were rich in the Antoni B area. MMP-9 expression was low in the Antoni A and B areas. MMP-2 was moderately expressed. No significant difference in MMP-2 expression existed between the Antoni A and B areas (P > 0.05). VEGF and MMP-14 expression were moderate in the Antoni A area and intense in the Antoni B area, and the expression of both was significantly greater in the Antoni B area than in the Antoni A area (P < 0.001). MMP-14 and VEGF expression were significantly greater in the Antoni B area than in the Antoni A area. Upregulated MMP-14 may degrade loose collagen in the Antoni B area and contribute to cystic formation. MMP-14 can enhance VEGF activity, which may induce extravasation of a plasma ultrafiltrate, cystic expansion, and intratumoral hemorrhage. Therefore, MMP-14 inhibition may be a therapeutic strategy for treating cystic VSs.

Low-Temperature Direct Contact Membrane Distillation for the Treatment of Aqueous Solutions Containing Urea

Research activities on the application of direct contact membrane distillation (DCMD) for processing at low temperature (up to 50 °C) solutions containing urea were presented and discussed. Feeds were urine (also in mixture) and human plasma ultrafiltrate. Moreover, as a case study, the performance of membrane modules of different sizes and features was investigated for reaching the productivities needed in the treatment of the human plasma ultrafiltrate. In particular, two modules were equipped with the same type of capillaries, but differed in terms of membrane area, while the third module contained a different type of membranes and presented a membrane area in between those of the two previous modules. The three modules were compared, at a parity of operating temperatures and streams velocity, in terms of transmembrane flux, permeate production and size, underlining the directions to follow for a real implementation of the technique.

Determination of Total and Unbound Meropenem, Imipenem/Cilastatin, and Cefoperazone/Sulbactam in Human Plasma: Application for Therapeutic Drug Monitoring in Critically Ill Patients.

Critically ill patients show several pathophysiological alterations that can complicate antibiotic dosing. Hence, there is a strong rationale to individualize anti-infective dosing in these patients by using therapeutic drug monitoring (TDM). The current study aimed to develop and validate a liquid chromatography-tandem mass spectrometry method for the simultaneous determination of total and unbound plasma concentrations of 3 commonly used antibiotics (meropenem, imipenem/cilastatin, and cefoperazone/sulbactam) in the treatment of infections in critically ill patients in China, which could be suitable for routine TDM in hospital laboratories. The unbound drug was separated from the bound drug by ultrafiltration. Simple protein precipitation was used for sample preparation. Meropenem, imipenem/cilastatin, cefoperazone/sulbactam, and their corresponding internal standards were then resolved using the Waters CORTECS C18 column. All the compounds were detected using electrospray ionization in the positive/negative ion-switching mode. The calibration curves were linear for all compounds, with correlation coefficients (R) above 0.99 for total concentrations in human plasma and unbound concentrations in the plasma ultrafiltrate. For both total and unbound drugs, the relative errors and intra-assay/interassay relative standard deviations were below 15%. The limit of quantification was 0.05 mcg/mL for both total plasma concentrations and plasma ultrafiltrate concentrations of all compounds. The method was simple, rapid, and reliable and is currently being used to provide a TDM service to enhance the efficacious use of the 3 antibiotics.

Filter-Membrane-Based Ultrafiltration Coupled with Surface-Enhanced Raman Spectroscopy for Potential Differentiation of Benign and Malignant Thyroid Tumors from Blood Plasma.

ObjectiveThe objective of this study is to evaluate the performance and feasibility of surface-enhanced Raman spectroscopy coupled with a filter membrane and advanced multivariate data analysis on identifying and differentiating benign and malignant thyroid tumors from blood plasma.Patients and MethodsWe proposed a membrane filter SERS technology for the differentiation between benign thyroid tumor and thyroid cancer. That is to say, by using filter membranes with optimal pore size, the blood plasma samples from thyroid tumor patients were pretreated with the macromolecular proteins being filtered out prior to SERS measurement. The SERS spectra of blood plasma ultrafiltrate obtained using filter membranes from 102 patients with thyroid tumors (70 thyroid cancers and 32 benign thyroid tumors) were then analyzed and compared. Two multivariate statistical analyses, principal component analysis-linear discriminate analysis (PCA-LDA) and Lasso-partial least squares-discriminant analysis (Lasso-PLS-DA), were performed on the SERS spectral data after background subtraction and normalization, as well as the first derivative processing, to analyze and compare the differential diagnosis of benign thyroid tumors and thyroid cancer.ResultsSERS measurements were performed in blood plasma acquired from a total of 102 thyroid tumor patients (benign thyroid tumor N=32; thyroid cancer N=70). By using filter membranes, the macromolecular proteins in blood plasma were effectively filtered out to yield high-quality SERS spectra. 84.3% discrimination accuracy between benign and malignant thyroid tumor was achieved using PCA-LDA method, while Lasso-PLS-DA yields a discrimination accuracy of 90.2%.ConclusionOur results demonstrate that SERS spectroscopy, coupled with ultrafiltration and multivariate analysis has the potential of providing a non-invasive, rapid, and objective detection and differentiation of benign and malignant thyroid tumors.

Total, renal and hepatic clearances of doxorubicin and formation clearance of doxorubicinol in patients with breast cancer: Estimation of doxorubicin hepatic extraction ratio

Doxorubicin (DOX) is a cytotoxic drug which has remained as an essential component of chemotherapy regiment for breast cancer. The cardiotoxicity of DOX is related to the accumulation of its main metabolite doxorubicinol (DOXOL) in the cardiac tissue. Although the pharmacokinetics of DOX shows high interindividual variability, there are no significant covariates to improve dose adjustment. The present study reports the pharmacokinetics of both DOX and DOXOL in a homogeneous population of young female patients with breast cancer (n = 12) making use of a standardized drug association, evaluated in the very first chemotherapy cycle, using plasma and urine data that allowed the calculation of the renal clearance of DOX, the formation clearance of DOXOL and the hepatic clearance of DOX. The extensive data availability also made it possible to estimate the hepatic extraction ratio of DOX for the investigated population, as well as to determine DOXOL unbound fraction in plasma for the first time in humans. DOX and DOXOL simultaneous analysis in plasma, plasma ultrafiltrate, and urine were performed by liquid chromatography coupled to mass spectrometry (LC–MS/MS). The pharmacokinetics profile of both DOX and DOXOL showed high variability (geometric coefficient of variation of area under the plasma concentration versus time curve extrapolated to infinity was approximately 215 %). The geometrics means were 0.26 for DOXOL/DOX AUC ratio, 15 % and 17 % for unbound fractions of DOX and DOXOL, respectively, 30.70 L⋅h−1 for total clearance, 0.66 L⋅h−1 for renal clearance, 29.97 L⋅h−1 for hepatic clearance and 0.39 L⋅h−1 for the formation clearance of the metabolite DOXOL. The 95 % confidence interval of the estimated hepatic extraction ratio of DOX ranged from 0.14 to 0.79, which characterizes DOX as a drug of low, intermediate or high hepatic extraction ratio.