Selective but not pan-CDK inhibition abrogates 5-FU-driven tissue factor upregulation in colon cancer.

Thromboembolic events are complications in cancer patients and hypercoagulability has been linked to the tissue factor (TF) pathway, making this an attractive target. Here, we investigated the effects of chemotherapeutics and CDK inhibitors (CDKI) abemaciclib/palbociclib (CDK4/6), THZ-1 (CDK7/12/13), and dinaciclib (CDK1/2/5/9) alone and in combination regimens on TF abundance and coagulation. The human colorectal cancer (CRC) cell line HROC173 was treated with 5-FU or gemcitabine to stimulate TF expression. TF+ cells were sorted, recultured, and re-analyzed. The effect of treatment alone or in combination was assessed by functional assays. Low-dose chemotherapy induced a hypercoagulable state and significantly upregulated TF, even after reculture without treatment. Cells exhibited characteristics of epithelial-mesenchymal transition, including high expression of vimentin and mucin. Dinaciclib and THZ-1 also upregulated TF, while abemaciclib and palbociclib downregulated it. Similar results were observed in coagulation assays. The same anticoagulant activity of abemaciclib was seen after incubation with peripheral immune cells from healthy donors and CRC patients. Abemaciclib reversed 5-FU-induced TF upregulation and prolonged clotting times in second-line treatment. Effects were independent of cytotoxicity, senescence, and p27kip1 induction. TF-antibody blocking experiments confirmed the importance of TF in plasma coagulation, with Factor XII playing a minor role. Short-term abemaciclib counteracts 5-FU-induced hypercoagulation and eventually even prevents thromboembolic events.

Is Moxifloxacin a Treatment Option for Pancreatic Infections? A Pharmacometric Analysis of Serum and Pancreatic Juice.

Postoperative local infection is a major complication after pancreatic surgery. The aim of this prospective clinical trial was to assess the potential of moxifloxacin (MXF) to treat pancreatic infections from a pharmacokinetic (PK)/pharmacodynamic (PD) perspective. The PK of MXF in serum and pancreatic juice, via an inserted tube in the pancreatic duct, was determined in 19 patients up to day 7 after pancreatoduodenectomy. PK data in both specimens was analyzed with NONMEM 7.3. Intraoperative swipes were performed for microbiological examination. PK/PD target attainment was assessed in both matrices using unbound area under the plasma concentration-time curve/minimum inhibitory concentration (MIC) targets of ≥30 and ≥100, for gram-positive and gram-negative pathogens, respectively. A 2-compartment population PK model in which the measurements in pancreatic juice were assigned to a scaled peripheral compartment best described the PK in both specimens simultaneously. Median (10th-90th percentile) area under the plasma concentration-time curve values after the third dose were 28.9 mg · h/L (18.6-42.0) in serum and 55.8 mg · h/L (23.7-81.4) in pancreatic juice. Target attainment rate for the intraoperatively isolated bacterial strains was ≥0.88 after the third MXF dose. For gram-negatives, high probability of target attainment ≥0.84 was observed in serum for MIC ≤ 0.125 mg/L and in pancreatic juice for MIC ≤ 0.25 mg/L. For gram-positives, the probability of target attainment was 0.84-1 in serum for MIC ≤ 0.5 mg/L and in pancreatic juice for MIC ≤ 1 mg/L. In conclusion, penetration of MXF into pancreatic juice was substantial. The PK/PD analysis indicated that treatment of pancreatic infections by isolates with MIC ≤ 0.25 mg/L (gram-negative) and ≤1 mg/L (gram-positive) should be evaluated in further studies.

Adipose-derived mesenchymal stem cells release microvesicles with procoagulant activity.

Extracellular vesicles are produced by a number of different cell types, among them mesenchymal stromal/stem cells (MSC) of different sources. It has been shown that extracellular vesicles of MSC exert similar therapeutic effects as the cells themselves. Here, we isolated and characterized extracellular vesicles produced by adipose-derived MSC (adMSC) in vitro upon stimulation with the proinflammatory substances lipopolysaccharide (LPS) and tumor necrosis factor (TNF). We found that the number of vesicles produced by adMSC does not change upon stimulation of the cells with LPS and TNF. Furthermore, adMSC-derived extracellular vesicles exert procoagulant activity independent of previous stimulation with LPS or TNF. We found evidence that the vesicles induce coagulation via both the intrinsic and the extrinsic pathway of coagulation.

Studies on the interaction of polylactid-based planar and nanoparticular biomaterials with serum albumin and fibrinogen.

Knowledge about the interactions of biomaterials with biological matrices is still poor however crucial to future development in terms of how to cope with immunomodulatory adverse effects and to control the integration of implants into tissue or the targeting of nano devices. The appropriate design of a material depends on reliable data about the influence of oligomer or polymer configuration and dispersity as well as surface properties including chemical modifications. This work addressed the interaction of four polylactide (PLA) resomers, a well-established, biodegradable biomaterial, and two physiologically relevant proteins, which are ubiquitous in human serum - albumin (HSA) and fibrinogen (HFG). Bovine serum albumin (BSA) was carried along as reference. The amount and stability of protein binding to plane material was assessed by surface plasmon resonance (SPR), the formation of protein corona around NPs by nanoparticle tracking analysis (NTA). The results demonstrated the particular value of SPR and NTA as techniques for the characterisation and prediction of the interactions of implants or NPs with matrix components. Both techniques are complementary with respect to a deeper understanding of changes in the layer composition with time, which is known as the Vroman effect, and, therefore, are considered of value for affecting the interaction processes by material design.

Influence of sirolimus-loaded nanoparticles on physiological functions of native human polymorphonuclear neutrophils.

Sirolimus (SRL) is an immunosuppressive agent of high clinical relevance that has been associated with serious side effects. Biodegradable, SRL-loaded poly(d,l-lactide) nanoparticles (SRL-PLA-NPs) are being investigated as a drug delivery system to improve drug targeting. Polymorphonuclear neutrophils (PMNs) are phagocytes for particulate xenobiotics and also important trigger cells of the primary immune response. Therefore, the effects of SRL, SRL-PLA-NPs, and plain PLA-NPs on the viability of human PMNs, their essential functions, and the secretion of relevant cytokines were determined and evaluated with respect to the intracellular concentrations assessed by liquid chromatography-mass spectrometry ultra-trace analysis. For the first time to our knowledge, incorporation of NPs into PMNs was monitored by flow cytometry using fluorescence-labeled NPs. SRL accumulated intracellularly, exceeding therapeutic blood levels by a factor of two to four. Phagocytic activity was promptly reduced but recovered within 3 hours. No other parameters of the PMNs were affected. Hence, PLA-NPs appear suitable as drug carriers for SRL, allowing for better control of drug release. FROM THE CLINICAL EDITOR: This team of authors describe the incorporation of sirolimus loaded florescent NPs into polymorphonuclear neutrophils, a process that has been monitored by flow cytometry utilizing the fluorescent properties of the polymeric NPs. SRL accumulated intracellularly, exceeding therapeutic blood levels by a factor of two to four, resulting in reduced phagocytic activity that recovered within 3 hours.

Pharmacokinetics and penetration of moxifloxacin into infected diabetic foot tissue in a large diabetic patient cohort.

OBJECTIVES: Physiological changes occurring in patients with diabetes may affect the pharmacokinetics and penetration of antimicrobial agents into peripheral tissue. We examined the pharmacokinetics and the penetration of moxifloxacin into perinecrotic tissue of diabetic foot lesions in patients with diabetic foot infections (DFI). PATIENTS AND METHODS: Adult patients suffering from type 2 diabetes mellitus and hospitalized for DFI (Texas classification of at least B2) were treated with 400 mg moxifloxacin intravenously (IV) or orally (PO) once daily. The pharmacokinetics of moxifloxacin and its concentration 3 h after administration in samples of perinecrotic tissue resected from infected diabetic foot wounds were determined at steady state (days 4-8). RESULTS: A total of 53 patients with diabetes mellitus type 2 (mean age 69.4 ± 10.8 years) were included in the study, of whom 28 received PO and 25 IV moxifloxacin therapy for a median of 8 days. In the PO and IV subgroups, the mean maximum observed plasma concentration (C (max)) in plasma was 2.69 and 4.77 mg/l at a median of 2 [time to reach C (max) (T (max)) range 1.0-8.0 h] and 1 h after administration, respectively. A mean area under the plasma concentration-time curve from time 0 until the last quantifiable plasma concentration (AUC(0-24 h)) of 29.36 mg h/l (PO) and 27.09 mg h/l (IV) was achieved. Mean moxifloxacin concentrations in perinecrotic tissue of infected diabetic foot wounds following PO or IV administration were 1.79 ± 0.82 and 2.20 ± 1.54 µg/g, thus exceeding the MIC(90) (minimum inhibitory concentration required to inhibit growth of 90% of organisms) for Staphylococcus aureus (0.25 mg/l) by seven- and eightfold and the MIC(90) for Escherichia coli (0.06 mg/l) by 29-fold and 36-fold, respectively. The mean tissue-to-plasma ratios of moxifloxacin concentration 3 h after administration were 1.01 ± 0.57 (PO) and 1.09 ± 0.69 (IV). Significant differences between the routes of administration were observed for T (max) and C (max) (P < 0.01), but not for other clinically relevant parameters (AUC(0-24); moxifloxacin DFI tissue concentration). CONCLUSIONS: The plasma concentration-time curve of moxifloxacin in diabetic patients is similar to that of healthy volunteers. We also observed a good penetration of moxifloxacin into inflamed DFI tissue which taken together with the possibility of sequential IV/PO therapy suggest that moxifloxacin 400 mg once daily is a therapeutic option in the treatment of DFI caused by susceptible organisms.

New coated SPME fibers for extraction and fast HPLC determination of selected drugs in human blood.

Polythiophene (PTh) and polypyrrole (PPy) as sorbent phases for solid phase microextraction (SPME) were applied in order to extract the multi-resistant Staphylococcus aureus (MRSA) antibiotic drugs (linezolid and daptomycin) from whole blood followed by high performance liquid chromatography (HPLC) determination with UV detection. Relative standard deviations (RSDs) of in vitro and pseudo in vivo measurements performed in whole blood were in the range of 4.58-15.91% and 6.09-17.33% for linezolid and daptomycin, respectively. Determination coefficients (R(2)) were in range of 0.9884-0.9945 and 0.9807-0.9818 for linezolid and daptomycin, respectively. This study proved better adsorption capacity of PTh SPME coating compared to PPy coating for both, linezolid and daptomycin.

Polypyrrole solid phase microextraction: A new approach to rapid sample preparation for the monitoring of antibiotic drugs.

Simple or even rapid bioanalytical methods are rare, since they generally involve complicated, time-consuming sample preparation from the biological matrices like LLE or SPE. SPME provides a promising approach to overcome these limitations. The full potential of this innovative technique for medical diagnostics, pharmacotherapy or biochemistry has not been tapped yet. In-house manufactured SPME probes with polypyrrole (PPy) coating were evaluated using three antibiotics of high clinical relevance - linezolid, daptomycin, and moxifloxacin - from PBS, plasma, and whole blood. The PPy coating was characterised by scanning electron microscopy. Influences of pH, inorganic salt, and blood anticoagulants were studied for optimum performance. Extraction yields were determined from stagnant media as well as re-circulating human blood using the heart-and-lung machine model system. The PPy-SPME fibres showed high extraction yields, particularly regarding linezolid. The reproducibility of the method was optimised to achieve RSDs of 9% or 17% and 7% for SPME from stagnant or re-circulating blood using fresh and re-used fibres, respectively. The PPy-SPME approach was demonstrated to meet the requirements of therapeutic monitoring of the drugs tested, even from re-circulating blood at physiological flow rates. SPME represents a rapid and simple dual-step procedure with potency to significantly reduce the effort and expenditure of complicated sample preparations in biomedical analysis.

No clinically relevant CYP3A induction after St. John's wort with low hyperforin content in healthy volunteers.

OBJECTIVE: Induction of CYP3A by St. John's wort (SJW) products with high hyperforin content is well described. Since CYP3A induction is mediated by hyperforin in a concentration-dependent manner, and SJW preparations differ significantly in hyperforin content, the aim of the study was to evaluate the effect of an SJW powder with low hyperforin content on CYP3A function. METHODS: Twenty healthy male volunteers received an SJW powder with low hyperforin content for 2 weeks. Midazolam plasma concentration time profiles were characterized after a single oral dose of 7.5 mg midazolam on the day before and on the 14th day of SJW medication. RESULTS: Midazolam AUC(0-infinity) slightly decreased from 124.0 +/- 62.5 ng/ml.h at baseline to 105.6 +/- 53.2 ng/ml.h after SJW (P < 0.05), representing a mean 11.3% decrease (95% CI: -22.8 to 0.21). No significant change in midazolam C(max), t(1/2) and t(max) was observed. For all pharmacokinetic parameters, the 90% CI for the geometric mean ratio of treatment over baseline were within the no-effect boundaries of 0.70-1.43. CONCLUSION: Administration of an SJW product with low hyperforin content resulted in a mild induction of CYP3A not considered clinically relevant.

Single- and multiple-dose pharmacokinetics of intravenous moxifloxacin in patients with severe hepatic impairment.

OBJECTIVES: The aim of this study was to investigate the single- and multiple-dose pharmacokinetics (PK) of moxifloxacin and its penetration into ascitic fluid in patients with severe liver insufficiency (Child-Pugh class C). PATIENTS AND METHODS: In a single-centre, prospective, open-label study, nine adult cirrhosis patients were treated with 400 mg moxifloxacin infusion once a day. On days 1 and 3, drug concentrations in serum and ascites were determined before and at different time points up to 24 h after medication with a validated HPLC method. RESULTS: On day 1, serum concentrations of moxifloxacin decreased from a median of 3.7 mg/L at 1 h to 0.6 mg/L at 24 h. On day 3, serum peak and trough levels were only moderately increased in comparison with day 1, with moxifloxacin concentrations of 3.9 mg/L after 1 h and 0.6 mg/L 24 h after the third infusion. The AUC values were also slightly, but not statistically significantly, increased on day 3. Calculations of t(1/2), mean residence time, CL(tot) and V(ss) revealed no significant differences between days 1 and 3. Median concentrations of moxifloxacin in ascitic fluid were 1.4 mg/L (3 h after infusion) and 1.3 mg/L (6 h) on day 1 and 2.1 mg/L (3 h) and 1.9 mg/L (6 h) on day 3. Median ascites/serum ratios did not vary between days 1 and 3. CONCLUSIONS: PK parameters of moxifloxacin in patients with advanced liver cirrhosis differed only marginally from those from healthy control groups given in the literature. After multiple dosing, no drug accumulation was seen. Therefore, we conclude that a dose adjustment is not necessary in this patient group. Ascitic fluid reached bactericidal levels for common bacteria found in spontaneous bacterial peritonitis.

Determination of antibiotic drug concentrations in circulating human blood by means of solid phase micro-extraction.

BACKGROUND: Promising results in animals have shown the diagnostic potential of polypyrrole coated SPME fibres introduced directly into the blood stream. This study was intended to extend this technique to a clinically relevant antibiotic drug under close to physiological conditions in human blood. METHODS: An artificial vein system was built up from heart and lung machine components. Determination of Linezolid (0-15 mug/mL) was performed by SPME from the flowing system ("online", flow velocities 2-50 cm/s), from blood withdrawn from the system ("offline") and by means of a SPE/HPLC method. SPME was done using new fibres ("new") for each analysis, and in the way that one fibre was reused ("re") for one series of measurements. RESULTS: Drug SPME did not depend on blood flow velocities. Linear regression of data (concentration vs. amount extracted) yielded R(2)=0.998 for SPE/HPLC, R(2)=0.955 for SPME(online_new), 0.929 for SPME(online_re), 0.929 SPME(offline_new), 0.973 for SPME(offline_re), RSD were 52% (SPME(online_new)), 10% (SPME(online_re)), 47% (SPME(offline_new)), 18% (SPME(offline_re)), 8% (SPE/HPLC). CONCLUSIONS: In-vein SPME has the potential to minimize blood requirement for diagnostic purposes and to speed up analysis of clinically relevant drugs, if inter-fibre variation can be reduced through standardized manufacturing.

Penetration of moxifloxacin into the human pancreas following a single intravenous or oral dose.

OBJECTIVES: Failure to prevent secondary infectious complications in acute necrotizing pancreatitis (ANP) is attributable in part to the limited penetration of antimicrobial drugs. As newer quinolones are particularly attractive owing to their antimicrobial activity, for the first time we studied the penetration of moxifloxacin into pancreatic tissue in patients. PATIENTS AND METHODS: In this prospective, non-comparative clinical trial, 60 patients undergoing elective pancreas resection received a single oral or intravenous (iv) dose of 400 mg moxifloxacin for perioperative antimicrobial prophylaxis. The concentration of moxifloxacin was measured in samples taken from blood and from pancreatic tissue at the beginning and at the end of resection. RESULTS: Mean moxifloxacin concentrations in pancreatic tissue following iv or oral administration were 3.1+/-0.9 and 2.7+/-1.4 mg/kg at 3-3.7 h post-dose (first sampling) and 3.6+/-1.5 and 3.1+/-1.8 mg/kg at 4.3-5.3 h post-dose (second sampling), respectively. Corresponding mean plasma concentrations of moxifloxacin were 1.8+/-0.5 and 1.2+/-0.6 mg/L (first sampling) and 1.5+/-0.4 and 1.0+/-0.5 mg/L (second sampling), respectively. From first to second sampling, the mean tissue-to-plasma ratios varied from 1.8+/-0.6 to 2.6+/-1.2 (iv) and from 2.4+/-0.8 to 3.1+/-1.2 (oral). Pancreatic tissue concentrations of moxifloxacin exceeded the MIC90 for the relevant pathogens covered by moxifloxacin for at least 5 h after dosing. CONCLUSIONS: Moxifloxacin has been demonstrated to penetrate efficiently into human pancreatic tissue following iv or oral administration. From a pharmacological perspective, moxifloxacin appears to be promising for prophylaxis and treatment of local pancreas infections. Whether it is beneficial in the prevention and therapy of infectious complications in patients with ANP should be investigated in a controlled clinical trial.

A new simple HPLC assay for the quantification of ertapenem in human plasma, lung tissue, and broncho-alveolar lavage fluid.

Ertapenem is an important newer broad-spectrum carbapenem antibiotic covering various infections caused by common gram-positive and -negative aerobes and anaerobes. Due to its physicochemical peculiarities, pharmacokinetic data of other carbapenems are of limited value in predicting ertapenem distribution into particular compartments of the body. This raises demand for detailed pharmacokinetic studies and, as a consequence, rapid and specific ways of analysis. The HPLC assays for the quantification of ertapenem in biological matrices reported so far are based on columns of 4.6mm I.D. and involve pre-concentration by use of column-switching. However, automated column-switching technique is not standard equipment with all analytical laboratories. Furthermore, signal-to-noise ratios are likely not to be sufficient for quantification of specimens of low concentration. Therefore, a new HPLC/UV method based on narrow-bore column design using sample pre-cleaning by liquid-liquid extraction has been developed. The assay is rapid for specimen concentrations > or =1 mg/l and is easily tuned to achieve low quantification limits at high chromatographic resolution for lower concentrated samples. The method has been successfully applied to plasma, serum, lung tissue or cell homogenates, and broncho-alveolar lavage fluid with lower limits of quantification of 40 and 20 microg/l, respectively. It was also used for the pharmacokinetic monitoring of ertapenem in humans.

The extent of induction of CYP3A by St. John's wort varies among products and is linked to hyperforin dose.

OBJECTIVE: Induction of CYP3A by St. John's wort (SJW) extracts with high hyperforin (HYF) content is well described. Since SJW products vary in the amount of HYF and other main constituents, the aim of the study was to evaluate the effect on CYP3A function of SJW preparations with a range from very low to high HYF content. METHODS: Forty-two male, healthy volunteers were randomized into six parallel SJW medication groups with varying composition especially with regard to HYF content. Midazolam plasma concentration profiles were characterized after a single oral dose of 7.5 mg midazolam on the day before and on the 14th day of SJW medication. RESULTS: All SJW preparations tested resulted in a decrease in midazolam AUC, although the extent of the effect differed. The extract LI 160 (HYF 41 mg/day) decreased midazolam AUC0-12h by 79.4% (95% CI -88.6; -70.1), which was significantly greater than the effect by any other medication (p<0.05). SJW powder tablets 2.7 g/day (HYF 12 mg/day) resulted in a midazolam AUC0-12h decrease of 47.9% (95% CI -59.7;-36.2), while 2.7 g/day SJW powder tablets that were almost devoid of HYF (0.13 mg/day) reduced midazolam AUC0-12h by only 21.1% (95% CI -33.9; -8.3). Considering all six SJW medications tested, the extent of midazolam AUC decrease correlated significantly with increasing HYF dose (r=-0.765, p<0.001), but not with hypericin dose (r=-0.067; p=0.673). CONCLUSION: The extent of induction of CYP3A varies among St. John's wort products and depends on hyperforin dose.

Penetration of ertapenem into different pulmonary compartments of patients undergoing lung surgery.

Ertapenem is approved for the treatment of community-acquired pneumonia (CAP), but its in vivo penetration into lung tissue (LT), epithelial lining fluid (ELF), and alveolar cells (AC) is unknown. Fifteen patients undergoing thoracotomy were treated with 1 g intravenously for perioperative prophylaxis. Bronchoalveolar lavage was performed 1, 3, and 5 hours after ertapenem infusion. Normal LT was sampled at the time of lung extraction. Blood was collected before and at different time points up to 24 hours after infusion. Mean concentrations of ertapenem in plasma, ELF, and AC were at 1.0 hour, 63.1, 4.06, 0.004 mg/L; at 3.0 hours, 39.7, 2.59, 0.003 mg/L; and at 5.0 hours, 27.2, 2.83, 0.007 mg/L. Mean (range) concentration in LT was 7.60 (2.5-19.4) mg/kg tissue 1.5 to 4.5 hours after infusion. In plasma, ertapenem exhibited a Cmax of 94.7 +/- 23.3 mg/L and an AUC(0-last) of 501.1 +/- 266.3 mg x h/L. These results, combined with the reported (MIC)90 of most CAP bacteria, support the previously observed clinical efficacy of ertapenem in the treatment of CAP.

The penetration of moxifloxacin into the pancreas of male rats in experimental acute necrotizing pancreatitis.

Infectious complications of acute necrotizing pancreatitis (ANP) determine the extent of multiorgan failure and account for 80% of deaths. Prophylactic use of antibiotics can reduce the incidence of these complications. However, the actual indication as well as choice of drug remains a controversial matter. We examined the penetration of moxifloxacin, a new broad-spectrum fluoroquinolone, in healthy and inflamed pancreatic tissue in rats after inducing ANP. The concentration of moxifloxacin in pancreatic tissue and serum was determined 10, 30, 60 and 240 min after the administration of moxifloxacin (5 mg/kg, i.v.). Mean serum concentrations 10 min after administration in rats with ANP were 1,886 ng/ml versus 1,805 ng/ml in healthy controls, and these values decreased to 350 versus 222 ng/ml, respectively, after 240 min. Corresponding concentrations in pancreatic tissue were in the mean 2-3 times higher.

Pharmacokinetics of piperacillin-tazobactam in anuric intensive care patients during continuous venovenous hemodialysis.

The pharmacokinetics of piperacillin-tazobactam were investigated in eight anuric intensive care patients treated by continuous venovenous hemodialysis (CVVHD). The elimination half-life of piperacillin was 4.3 +/- 1.2 h, and that of tazobactam was 5.6 +/- 1.3 h. The contribution of CVVHD to the overall elimination was relevant (>25%) for both drugs.

Investigation of the pharmacokinetics of celecoxib by liquid chromatography-mass spectrometry.

A new method for the quantification of celecoxib in human plasma based on reversed-phase high-performance liquid chromatography (HPLC) coupled to atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) after liquid-liquid extraction is presented. The method is rapid, sensitive and highly selective. The retention time of celecoxib was 2.3 min. The limit of quantification was 5 microg/L. Rofecoxib was used as internal standard. After validation, the method was used to study the pharmacokinetic profile of celecoxib following administration of a single oral dose (200 mg) in 12 healthy volunteers. Since celecoxib should be metabolized primarily by cytochrome 2C9 (CYP2C9), a poor metabolizer (PM) for this cytochrome P450 enzyme was included in the study. Pharmacokinetic characteristics (mean +/- SD) of extensive metabolizers (EM) were t(max) 2.9+/-1.2h, c(max) 842+/-280 microg/L, AUC(infinity) 6246+/-2147 microg h/L and t(1/2) 7.8+/-2.7h. The area under the curve (AUC(infinity)) for the PM was 12561 microg h/L. However, we found no noticeable increase in half life in the PM (11.5 h) after a single dose of celecoxib.